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CHARGING VOLTAGE
Charging voltage is different. Some more basics: If you read
articles on how electricity flows, you see comparisons as to
how water flows. This is okay up to a point, but water also flows
by gravity. Electricity doesn't, it has to be "pushed"
(just as water has to sometimes be pumped).
You have to have more "juice" at one end of a wire
than you need at the output or electricity won't flow. The wire
you pump electricity through and the connections in the lines
resist the flow. You have to overpower it. Similarly, batteries
have an inherent resistance to take a charge because of their
chemical makeup. It's like "making a blivet" (a blivet
is 10 pounds of poop in a 5 pound bag). You have to force more
electricity into a battery than it would like to accept or it
won't be fully charged. To charge a standard 12-volt battery,
you have to bring it up to above 14 volts (amount varies with
the type of battery).
The typical wet-cell battery (a tub of lead plates in a mixture
of sulfuric acid and water) needs to be charged up to about 14.+
volts in order to adequately distribute those funny little things
called electrons through the plates. Once that's done, the battery
can rest. As it does, the electrons distribute themselves and
eventually balance out at 12.6 volts (more or less, depending
on the type battery and its condition). This is your starting
point. Doesn't sound like much, does it?
MORE AMPS AND VOLTS
I mentioned earlier that you should only draw a battery down
to about 12.3 volts before recharging. Obviously, there's more
to it than that. Amperes are the measure of actual power available.
They're usually converted to amp(ere) hours (AH). Think of it
as the amount of (nominal) 12-volt power you can draw out of
a battery for a certain amount of time. It's not just three-tenths
of a volt. It's 12 (nominal) volts for a certain amount of time.
The three-tenths stuff is nothing more than a difference in measurement
-- like the difference between three-fourths of a tank of gas
and a half tank.
Look at voltage as two things: First, a force that pushes
electrons -- Second, as a handy measurement.
Look at amperes as two things: First, a quantity of energy
(like you would a gallon of gas) -- Second, as a handy measurement.
From a (nominal again, don't forget) 12-volt tub of energy, you
can extract just so many amperes of power.
Keep in mind that the laws of physics prevent you from getting
more out of something than you put into it! Keep in mind that
waste (those wires, battery contents and such) prevents you from
taking out as much as you put in. Keep in mind that you're going
to have to put in about 10% more electrical power than you use
(high school physics). A battery bank is like a "money"
bank or checking account -- if you repeatedly take more out than
you put in, you'll eventually be in trouble.
MORE ON CHARGING
Not all batteries are the same. Standard wet-cell batteries can
be charged to 14.+ volts (usually 14.3 but depends on the manufacturer).
Gel-cell batteries and other sealed batteries should never be
charged to more than about 14.1 volts (again, may vary depending
on manufacturer). And these figures only pertain when the charger
will be disconnected as those levels are reached (as with a generator,
solar system, portable charger, or engine alternator). As the
volts drop (usually down to about 12.6 to 13.3), charging begins
again, either manually or through an automatic regulator. Note
also: The maximum charging voltage quoted for gels by the manufacturer
is as a sustained voltage, not an intermittent one. That means
brief over-voltages before a regulator shuts off are OK.
Sustained charging, where the batteries are "floated"
at a constant charge (as in the RV converter or with an automatic
portable charger) should not be done at more than 13.8 volts
(and 13.65 makes batteries last longer). It's supposed to keep
the batteries "up" to a reasonable level without undercharging
or overcharging them (the assumption being you'll "top them
off" by driving). Unfortunately, many cheap chargers and
RV converters don't regulate very well. Overcharging destroys
batteries quickly. Undercharging destroys batteries too, but
more subtly as the battery stratifies and will no longer maintain
a charge. In effect, the 100 amp/hour RV battery becomes a 10
amp/hour battery after consistent undercharge. It will read full
voltage, but as soon as a small load is placed on it, it drops
to nothing. RVers who remain plugged into commercial power for
long periods often never know this has happened until they unplug,
because the converter's transformer also supplies power directly
to the RV circuits while it's charging the battery -- or trying
to. (More later.)
EQUALIZING
Sometimes an equalizing charge can correct the above situation.
BUT, don't ever try to equalize a really sealed wet battery
or gel-celled or AGM battery! You've got to be really careful
when doing this! The battery is going to "gas" (bubbles
in the cells, hydrogen gas escaping). It shouldn't be violent,
spewing acid an over the place, just gentle to rapid bubbling
but it requires caution. It's usually done by hooking up a manual
charger, then bringing the voltage up to 14.1 or 14.3 and, instead
of stopping as usual, keeping it there, at about a 5-amp charge,
for three to six hours (until voltage reaches 14.5 to 15). Do
this with the caps off of a standard battery so you can see what's
going on. About three hours is usually normal for one of these
equalizing charges.
Follow safety precautions, use safety goggles, plenty of ventilation,
etc. If it works, you lucked out. If not, buy a new battery (as
you should have in the first place).
Some battery people recommend equalizing in this manner every
three months (or after 5 deep cycles). I think the wear and tear
on a 12V battery from equalizing this often does more damage
than it's worth.
Batteries held at 13.8 or so for long periods get lazy and
like it there. They need some "equalizing" also. Not
as drastic as above, fortunately. If you drive occasionally,
your engine alternator should do it (assuming the regulator is
set properly). So will a solar electric system or a good, well-regulated
independent battery charger. If nothing else, use the manual
charger once in a while when parked and plugged in, but just
bring volts up to 14.+ (whatever's appropriate) and stop there.
Six volt heavy-duty batteries (like golf carts, etc.) differ.
Their heavy plates and other construction features allow periodic
equalizing. I recommend the same 5 amp charge rate, for three
to six hours (until voltage reaches a maximum of 16.5) every
six months or so. It varies, with some people doing it monthly
(which might mean another problem).
CHARGE/DISCHARGE RATE
You'll see references in battery books to the proper charge rate.
C/10, C/20, etc. Sometimes it can be confusing. What you need
to know is that it means the "time" it takes to fully
charge a "dead" battery at a certain amp rate. For
example: A 105AH battery will fully recharge (from dead) in about
10 hours at about 10 amps of charge (C/10) or about 20 hours
at 5 amps of charge (C/20). Faster charge rates, like C/5 or
C/8 shouldn't be used with most batteries because the high amperage
required for such a fast charge damages the battery. C/5 on a
dead 105AH battery requires pounding in over twenty amps. (This
is sufficient reason to stay away from fast-chargers in service
stations where a gigantic amount of amps are pummeling your battery
when they "charge" (destroy) it in 20 minutes. And
when you buy a battery off the shelf, don't let the guy "put
it on a charger for just a few minutes" or it will be damaged
before you ever use it.
Now, for real life: You'll seldom be charging a "dead"
battery. The C/20 rate of 5 amps will charge your partially discharged
battery just fine in a lot less than 20 hours. And, since your
typical RV converter only puts out a low amp charge anyhow (only
3 or 4 or so), you're about at the safe C/20 rate all the time.
If you're in a hurry, plug in your manual charger as well and
just keep an eye on things.
TROUBLESHOOTING AND TESTING
Don't just replace batteries and keep on trucking! Find out what
went wrong first. Is the converter working? Voltage too high?
Too low? Is it connected to the battery? Fuse blown? Wire broken?
Contacts cruddy? Kill switch on motor home on or off (whichever
is appropriate -- and the wrong position a common fault among
motor homers)? How many times have you deep-cycled? Short in
the system? Been hooked up a long time? Automotive regulator/alternator
OK? (More later.)
Measuring, metering, testing and troubleshooting require only
a few tools and basic knowledge. Much of it is common sense,
requiring no tools. Do not ever depend on the red/yellow/green
idiot meter installed in most RV's. Get a digital meter. You
need a digital meter to accurately read battery voltage to tenths
of a volt. You should have an Analog (needle face) meter also.
You can't tell the difference between battery voltages with an
analog with great accuracy, but they are better in some ways
(because it's easier to see rapid changes) than digital meters
for reading fluctuations. (Much more later.)
Get a 12-volt troubleshooting light/test lamp from any auto
store cheap or make your own. (Meters will indicate voltage even
if there's only one strand left in a wire. Test lamps won't light
if there's not enough wire to carry the load.)
Get a decent hydrometer if you have wet-cell batteries and
can remove the caps. Don't get a cheapie with colored, floating
balls. Learn how to read a hydrometer. (See more later.)
MAINTENANCE
Maintenance is all-important. Crud on top of a battery provides
a path between poles. It's a "short." One most people
never notice, but it uses energy constantly.You don't need to
slop baking soda all over. Often just a spray 'n wipe with household
cleaner is all that's needed.
- Corrosion will build up. Some-times you can't even see it.
Take contacts apart and clean them. (Now is when you might use
baking soda, but don't let it get in the cells.) Done once or
twice a year, it's fast and easy.
- Before putting things back together, coat all surfaces (thinly)
with silicone dielectric grease. That's before, not after. You
won't accomplish a thing by smearing grease on top of corrosion.
- Never use red battery spray. It just makes things worse.
The red/green felt, noncorrosive washers are okay.
- Label or color-code cable and wire ends. Make a diagram.
If you don't, you'll just hook things up wrong. (More on maintenance
later.)
MORE DETAILS ON BATTERIES (MOSTLY GEL CELLS and AGM)
Much of the same material applies: All batteries need to be maintained.
All batteries need to be kept charged -- but not overcharged
or undercharged. All need clean connections and good, stout cable
and wire of the proper size. No battery should be routinely deep-cycled.
Of most importance, charging needs to be well regulated.
And here's where the difference between gels, AGMs and regular,
wet-cell batteries starts to show up seriously.
- Wet cell (flooded) batteries: Suspended plates, usually
with some form of separators (so plates don't touch each other)
are immersed in liquid electrolyte. These may be charged, just
as a starter battery, which makes things a lot simpler.
- Gel batteries: Plates are suspended in a thick gelled
electrolyte that insures stability and eliminates voids or "air
pockets" at the plates. The best gels are those by "East
Penn Mfg." (under "SeaGel," Prevailer" and
other labels -- but the East Penn name will appear somewhere).
Competitors are lite weights. Gels are seldom charged to more
than 14.1 volts initial (bulk) charge and 13.8 (13.65 is better)
as a "float" charge (see later).
- AGM (Absorbed Glass Mat) batteries: A dense fiber
matting between the plates and a liquid electrolyte provide
similar features to gel batteries but are much more rugged since
they were designed for use in aircraft and rough terrain vehicles.
The best AGMs are those made by "Concorde" (usually
under the "Lifeline" label but Concorde will appear
somewhere). AGMs (like gels) are very sensitive to overcharge.
14.38 volts is recommended for the initial (bulk) charge and
13.38 as a "float" charge.
Pros and Cons:
Standard, old-timey flooded batteries are cheap (initially).
They'll do the job (golf carts or similar better than RV/Marine
stuff). See remarks elsewhere. They will vent gas and fluid,
but it can be replenished with distilled water. They require
a lot of care.
Gells and AGMs can do a better job and last longer, BUT also
require special care. They're rather expensive initially (but
my six gels are in their tenth year, as good as new, and the
cost nets out to less than standard batteries). However,
they are very carefully charged and that requires an expensive
charger/regulator. Gels and AGMs don't need a lot of maintenance
and cleaning (other than a quick spray and wipe from a household
cleaner) UNLESS you do something stupid and overcharge them.
They won't spill acid, are very shock resistant, don't pass gas
(pun intended) unless seriously overcharged, have a VERY low
self-discharge rate (nice when the RV is in storage) and have
a very long cycle life.
I've used golf cart batteries, regular batteries and gels. As
I'll repeat with more detail elsewhere, golf carts and similar
batteries are, all things considered, the best solution. Were
I to have to replace my batteries today (they're in the living
compartment in a small RV), I'd go with AGM. In a bigger RV,
I'd go with golf cart or fork lift batteries.
You should never charge a gel battery to more than 14.1
volts (or to more than the voltage specified by the manufacturer)
before the regulator shuts off the charger except for very brief
periods. Then, as a battery is "floated" (kept on the
charger with a charge applied to keep it up to a reasonable level),
it should never exceed 13.8 volts (better, for long life is a
maximum of 13.65 volts). Again, though, you don't float the battery
permanently. You occasionally bring it up to 14.+ (this is EZ
with a solar regulator or better quality battery charger that
will perform regulating tasks frequently and automatically. (more
later.) AGMs are charged similarly, just with different
voltages.
Actually, you'd be foolish to keep (float) any battery at
a sustained charge of over 14 volts. You'd just wear it out prematurely
and it would be spewing acid all the time, making a mess. But
with a regular, wet-cell battery with removable caps, you can
add water and clean up the corrosion. With a gel, or any other
(really) sealed battery, you can't add water. All you can do
is watch the battery deteriorate.
Gel batteries and AGMs do have caps, but don't ever try
to remove them. First, you'll violate the warranty. Second,
you'll contaminate the inside. When it dies early, the dealer/factory
will know you did this and will void the warranty. Also, if you
overcharge a gel or AGM battery, the factory can detect that,
too. Again, no more warranty. Gel and AGM batteries are expensive.
Retailing at about $300 each in the Group 27 size, they are available
for less than $175 plus freight from many alternative energy
dealers. The best info source is SKP Noel Kirkby at "RV
Solar Electric". He can refer you to a good dealer (www.rvsolarelectric.com).
Check also with Back Woods Solar (www.backwoodssolar.com)
and West Marine (www.westmarine.com).
No matter what price, these are not $55 pieces of RV junk you
get at a discount store and return for almost full credit because
you screwed up.
So why bother with them? If they're expensive and so sensitive?
Because they do a superior job in some cases. Venting to outside
air isn't needed. (They can vent gas and fluid if you seriously
overcharge them or do something catastrophically stupid.) Moot
point, because you will take pains to never overcharge them anyway
(won't you?). You can keep them inside the RV (or in a basement
compartment). They stay clean and need very little service (other
than a spray'nwipe with household cleaner and an occasional check
for tight connections) and, more importantly, will be temperature
consistent (more later). Piling a bunch of batteries on the tongue
of a trailer or directly behind the grill of a Class "A"
motor home is not a good idea. you just overweigh the front of
the thing and end up with a wallowing vehicle. The back bumper
is also bad for the same reasons, plus more, as you overweigh
and flex the frame and create leaks (if you don't break the frame,
hitch or the vehicle skin). These battery mounting schemes also
lead to ultra-hot and ultra-cold temperatures.
TEMPERATURE
Temperature is important when charging any kind of batteries.
A really hot battery (EZ to achieve if they're sitting out in
a cheap, plastic box) will overcharge well before the voltages
listed earlier. Keeping batteries "indoors" helps keep
them at about an ideal temperature (of about 68 to 77ºF).
Actually, high temperature only becomes a real problem when the
battery is being "floated." A 13.8 volt float can easily
become a 14+ a-whole-bunch float at 90º. Temp can also be
a winter problem as batteries try to freeze and their amp hour
capacity is reduced by over 30%.
MORE ON REGULATING CHARGE
There are only a few RV converter/combination battery chargers
that are worth having. Most do an absolutely lousy job and you
haven't the faintest idea what wild voltage (or lack of) is going
to your batteries. Some converter/chargers do work. Check yours
no matter what kind of battery you use. With the thing operating,
and the battery reasonably-well charged, and not much more load
on the battery than the TV antenna amplifier and reefer brain
(RV reefers with a circuit board use 12 volts all the time, just
to operate the board), put a digital volt meter across the "house"
battery terminals. Leave it there awhile and see if it's holding
the batteries to around 13.8 volts. (Or is it charging them up
to something ridiculous?) (Or is it charging at all?) Some, even
fewer, RVs use a separate battery charger (not as part of a converter).
Generally, these are pretty good (and expensive). But check them
the same way. It's not at all uncommon to find stock RV battery
chargers floating batteries at 14.3 volts or higher. The best
chargers regulate in two, three or four stages. First, anytime
there's sufficient demand, they full charge to 14.+ volts (adjustable
by you). Second, they revert to a "float" charge of
about 13.8 (which in good chargers is adjustable again). Some
have a third, "equalizing" stage, automatic or manual,
that should also be adjustable. (There are some four-stage chargers
also.)
If you want to use gel or AGM batteries, you must have a good,
reliable, user-adjustable regulator and charger. The best way
to charge batteries is with a solar electric system. (Again,
check first and last with "RV Solar Electric" above.)
A solar system (if it has a user-adjustable regulator) will let
you set the charge cut-off at desired volts. Usually, anytime
the solar system achieves that, it will cut off and drop to about
13.1 volts before resuming (some solar regs will back off to
a float voltage). This gives the batteries a "rest"
and keeps them from overcharging. (And, of course, at night,
solar systems don't do anything, so there's a good rest, too.)
For a backup, you can use a generator or commercial power. Make
sure your generator (if it has a direct DC 12 volt charging outlet)
is set to regulate at proper volts! If it just charges through
your converter, you'll have checked that above, but recheck it
with the generator running. Do the same with an independent charger.
Many others are available. Check with "West Marine."
Huge catalog that has page-after-page of comparison info and
tips. If you're going to buy a big inverter anyway, consider
those with a battery charger option. For $220 additional (or
included at no cost), you get a user-adjustable charger that
would cost over $400 as a stand-alone. (See my Source
List and Inverter poop sheets.)
AUTOMOTIVE CHARGERS
How about the automotive charger when you're driving? Same drill.
Most automotive chargers (alternator and voltage regulator) are
factory set for cut off at 14.3 to 14.7 volts. There are user-adjustable,
automotive regulators. If you can't easily find one, check "Ample
Power," "West Marine" or, best of all,
"Wrangler Power Products" (see Sources).
Wrangler is especially easy to work with and most knowledgeable.
Ford products use external regulators, which makes it easier
(and cheaper). Some (like GM) and others use internal regulators
(built into the alternator). That's not too swell an idea anyway,
they get too hot and wear out. In those cases, you can get a
special alternator and external regulator. (Wrangler knows just
what will work.) It can get expensive, but most RVs need a better
alternator anyway.
CABLES AND CONNECTIONS
Tying the system together is important. No point spending a lot
of money on batteries and chargers and wiring it up with skimpy
junk. Large battery cables can be found in good auto stores like
Big A that carry things for trucks and West Marine that
carries things for boats. Best is to get cables from Wrangler
(www.wranglernw.com)
custom-made to your lengths with terminals that match your vehicle.
Smaller wiring is also important. You can get it locally, but
get the right size. Pay attention to terminal ends and splices.
Don't use the cheap clamp-on stuff that RV shops use.
DON'T EXPECT MIRACLES FROM GELS or AGMs!
Gels are expensive, require careful charging, monitoring with
a digital meter and protection from extreme temperatures. Most
of us who use them are pleased and sure the extra care is worth
it. Those who are not satisfied usually abused them or assumed
they would work miracles. Confusion abounds with these batteries.
They are not "regular" batteries. Amp Hour (AH) ratings
of these confuse everybody. Group 27 size only 86AH when almost
any RV/Marine battery is l05AH? Yes, BUT RV batteries are usually
25% overrated. There's more to it. There's AH and effective AH.
Gels (for example) are fully charged at a resting voltage of
12.9 to 13.1 volts instead of the usual 12.6 volts, thus start
to deliver electricity from almost 13 volts, instead of 12.6
and that equals more efficiency. Depending on use, you can get
more effective AH from gels than the rating. This does not mean
you can draw 250AH from a pair of gels in one day with heavy
loads and no recharging. Again, there's no magic or miracles.
Also, that difference in voltages means you can't just connect
a gel or AGM battery to a regular battery or to sets of golf
cart batteries. Nor should you connect regular batteries to golf
cart (or similar) battery sets. Mismatch will damage them.
TYPES OF GELS AVAILABLE
Sonnenschein (German) originated the principle and has been
selling the battery for many years. East Penn Mfg. bought U.
S. rights and is manufacturing and selling them under the DryFit
Prevailer or Deka label. These are the best gel-celled
batteries you can buy at this time. Johnson Controls (Dynasty)
and Exide (among others) are trying to compete, but their
batteries are lighter and, as of now, just don't measure up as
well. No doubt all this will change.
BATTERIES TO IMPROVE?
The government's electric car mandate has already resulted in
significant improvements in battery technology. It won't be too
long until these improvements are on the market. If the batteries
you have now are OK, you might want to baby them along, as long,
as you can. That means make sure your battery charger isn't over
or under charging, that you don't deep-cycle them and you maintain
them. If you need batteries, you should investigate gels (technically,
gelled electrolyte) or AGM.
6 VOLT BATTERIES
Check on 6 volt batteries also. The right 6 volt batteries, golf
cart or fork lift, connected in series-parallel to furnish 12
volts are, all things considered, the best battery source for
RVs. (More later.)
MORE DETAILS ON BATTERIES AND ASSOCIATED ELECTRIC THINGS
Giant, motive power, truly deep-cycle batteries (as used in industry)
are ideal for a fixed residence: but, with their enormous size
and weight are not practical in an RV. Similarly, a bank of 2-volt
telephone-cells connected in series-parallel (to = 12V) can provide
a super, long-life power source. Again, though, there would be
a space problem and the weight would be well over 600 pounds.
Eliminating these power sources out of necessity, let's also
eliminate another bad choice: The typical RV arrangement of one
or two automotive-grade batteries in plastic boxes mounted on
the tongue of a trailer. Out of sight and out of mind; never
serviced; corroding away in freezing cold and broiling sun; generally
two inches deep in water; green, cruddy terminals connected to
a bunch of multi-colored, go anywhere, frequently shorted wires.
The whole mess tied down with a plastic strap and buckle that
nobody can operate (so they never do), which is just as well,
maybe, because it will break.
Almost as bad is the huge, homemade plywood box that sits
on the rear bumper, has most of the same failures and interferes
with weight distribution. It puts undue stress on the frame and
creates leaks in the roof. At worst, it bends the frame and it
cracks the roof and sides (just like cargo boxes and motorcycles).
You can put some weight on a bumper, but not much. How much depends
on the RV, its GVWR and its construction. Frequent articles in
RV pubs point out the need for strict weight control. The articles
do nothing more than point out the rules of basic physics--heed
those rules or destroy your RV. Note, for example, that the further
the rear end is from the wheels, the less weight you can put
on the rear end. Note also that the further the front end is
from the wheels, the weight you add to the tongue can drastically
increase tongue weight. Too much tongue weight equals a broken
hitch.
If possible, RV batteries need to be in an inner compartment.
(A battery loses 30% or more of its capacity in cold weather.)
Most batteries need to be vented as well. This can cause problems
when using the next best thing to the giant batteries mentioned
above--pairs, in series parallel, of 6V fork lift or golf cart
batteries. These weigh more and are taller than standard batteries.
So, when they're crammed into an existing compartment, there's
no way to service them. (Most RV battery compartments don't allow
for servicing "normal" batteries either.)
If you only need two batteries, it's not too much of
a problem. You can build a slide-out tray (that probably won't
work well), ignore your batteries (the usual solution) or build
a better compartment. You can build an insulated battery box
on the tongue or bumper for two (maximum 4), but pay attention
to what you're doing--no heavy plywood, certainly no particle
board. An aluminum frame, with aluminum flashing can make a water-tight
box that weighs little. Lining it with urethane, aluminum-coated
foam is effective and also light weight. (You'll need a plywood
bottom, covered with aluminum, vinyl or fiberglass since batteries
weigh about 60 lbs each.) A spray of vinyl undercoating (fiberglass
gel coat if you know what you're doing) will acid proof the interior.
Best is to put the batteries inside the coach in a vented (if
necessary) compartment.
An example: I use six, true gel-cell batteries. The
same size as Group 27 (l05AH) RV batteries but much heavier.
Venting isn't necessary (if they ever gas, it means you've got
other problems). The batteries are easy to get to, stay clean
and are temperature consistent. Wiring is simpler. "Basement"
style trailers and motor homes can easily do the same thing,
with batteries well protected but outside the living area. A
further example: In my travel trailer I had six golf cart batteries
under the kitchen sink (in a vented compartment). Easy to get
to and maintain and, again, temperature consistent as well as
clean and easy to phiddle with. Get creative.
Here are two alternatives when using regular or golf
cart batteries in a tight place (neither totally successful):
Some people attempt to solve the non-access problem to batteries
in a small compartment with the use of "battery bobbers"
(clear plastic caps with floats inside) that let you peer inside
and estimate water level. A help, but some bobbers stick and
some leak and sink (that's the way things work now days). There's
still the matter of not being able to use a hydrometer, though
one can keep a pretty good eye on battery performance with a
digital voltmeter (if you take the time to learn what you're
doing). If the compartment is too tight, you can peer in and
get an idea of corrosion, but only with great difficulty and
with crud being spread around (and with spectacular pyrotechnics
when you short your wrist watch or ring to ground). At this point
some people buy "Hydrocaps" (not to be confused with
bobbers) which cost about $7 each, but really do reconstitute
vapor and prevent loss of fluid and gassing. Hydrocaps aren't
foolproof. If the battery is seriously overcharged and overheats,
the caps can melt down and the battery burst open. Catastrophe
time!
Back then to two choices: Put the batteries where they
can be serviced or use maintenance-free batteries. You say,
"I've heard all about those lousy things that die in 18
months." Fact is, they weren't really lousy, just very shallow
cycle batteries. Had the manufacturer told us this (that they
shouldn't be deep cycled), that problem wouldn't have resulted.
Also, these batteries (sealed wet-cell batteries) shouldn't be
overcharged much above 14V because they will gas and fluid can't
be added. No real problem there either -- if people know it.
These "wet" (fluid filled) sealed batteries have for
the most part been written off by serious RVers. Not so much
because of the shallow cycle (because in a properly sized system
you'll almost never deep-cycle your batteries anyway) and not
because of the critical voltage limit (because in a good system
you'll have an adjustable regulator that prevents overcharge),
but because they aren't really maintenance free, they are maintenance
prohibitive. They are vented, they can gas and when they do,
there's nothing you can do about it except watch them deteriorate.
True gel batteries have this same fault, but perform so well
many think they're worth the extra care needed.
There are some so-called maintenance-free batteries that
aren't really sealed. You can remove the caps and add fluid.
The caps do reconstitute some of the vapors and return fluid
to the cells. (Call them maintenance friendly?) On these, the
caps can be removed and fluid added and specific gravity checked.
In most cases though, the holes through the case (when caps are
removed) do not have any ridge around the edge to prevent crud
from going into the cells. Cleaning these is difficult as any
acid remover (baking soda) that gets into the cell will neutralize
it. Most of these batteries are intended as engine starting batteries.
They're not generally recommended as "house" batteries
unless the RV is driven frequently or on hook ups most of the
time because they have a very few deep cycles in them. (I had
one, in the small, Group 24 size, bought in 1980 for just a few
dollars. In almost constant use as a tool battery and charged
with excess energy from the solar system, it remained clean and
held a full charge after over 7 years. The secret? Maintenance
and careful charging.)
Some of the batteries I've tested: For over a year,
I tested three "sets" of batteries at the same time,
using each on alternate days. 2 Sears Die Hards, 2 Goulds
ActionPac, 2 Trojan T-105 golf carts. I won't go into
detail here. Conclusion was that the Golf Carts were superior
in every category (including cost). I wouldn't hesitate to use
golf carts (or better yet the L-16 Fork Lift batteries) again
if I had enough room for the bank of six that I need. For over
two years I tested a bank of six "StowAway/Watchman"
sealed, wet cell batteries. Maintenance prohibitive, but with
careful charge regulation there was little or no gassing and
when I disposed of them, all were as good as new. I then used
a bank of 6 golf cart batteries for over 5 years. They were as
good as new when I changed RVs. I then used 2 "Delco/Voyager"
maintenance-friendly batteries. They worked and didn't cost much.
They began to gradually degrade after two years.
I have now used, for over ten years, six Sonnenschien/DryFit
Prevailer/Deka true gel-cell, sealed batteries (not sealed
wet cell batteries). They perform better than any batteries I've
used. However, you must never overcharge these batteries. They
cost about $175 each at discount and up to $300 retail. They
must, therefore, be protected by an excellent regulator and charging
system (more cost). I now have another motor home and am installing
Concorde AGM batteries in it.
In Summary: If you have a large bus (not just a motor
home that looks like a bus), you should investigate the massive,
industrial batteries. If you have a reasonably-sized motor home
or trailer, consider the fork lift (Trojan L-16 or =)
or golf cart ("Trojan" 105, 125, 145 or =) --
assuming you have a place to put them. "Exide"
and "Interstate" also manufacture good golf
cart batteries. If space is minimal, cost is no object and reliability
is important, consider the AGM batteries or true gel cell batteries.
"Sonnenschien/DryFit Prevailer/Deka" are excellent.
Exide, Dynasty (from Johnson Controls Corp.) and Interstate
do make true gels at a lesser cost, but they are not as good
in my opinion. (They're trying to compete and doing so with lighter
-- thus cheaper -- material.) Eventually, they will produce batteries
as good as Sonnenschien (Sunshine in German). Finally, there's
the RV/Marine, so-called, deep cycle battery. They're
cheap and should last 3 to 5 years if you take care of them.
(Keep in mind that RV/Marine usually means any battery with a
rope tied to it.) I do not recommend sealed, wet-cell batteries
(the disadvantages of true gels with none of the advantages).
I do not recommend automotive batteries -- ever.
CHARGING AND RATINGS
This brings us to the rating of batteries. There is a whole bunch
of information that may or may not (and usually does not) appear
on a battery label.
CCA (Cold Cranking Amps)
A test conducted at 0°F, it measures the maximum current
a battery will produce, for only 30 seconds, down to an end voltage
of only 7.2V. (Note that maximum current is never stated.) This
test is valid only in selecting the battery to be used in starting
your engine. It cannot be converted to a figure useful in determining
low amp draw over long periods as in the RV house battery. (It
has to do with the extraction of electrons from the chemistry
of the battery. You're not interested in all that.) When buying
a starting battery, as long as the CCA is equal to, or greater
than, the cubic inch size of the engine, it's big enough (except
in the case of some diesels that need two starting batteries).
AH (Ampere Hour) Rating
A given number of amps for a given number of hours (amps x hours)
down to an end point of l0.5V is used to calculate the frequently
seen AH rating. The l0.5V end point is standard, but you seldom
see the actual amps and times used to calculate it. Some manufacturers
put the AH rating on their batteries; they just don't tell you
how they measured it. Usually, though, there's a chart listing
capacities in amps and time. Multiplying these will allow comparing
one brand against another. (They use a variety of times and amp
draws, but some should be the same.)
Reserve Capacity
This is a specific technical term (like CCA), but unlike CCA
it can be applied to battery ratings in a way that makes more
sense. Reserve capacity, in minutes, is the time it takes a battery
to reach the 10.5V end volts, at a 25 amp draw, at 80°F.
So, if reserve capacity is (x) amps for (y) minutes, then we
can calculate Amp Hours easily. Using a typical RV/Marine battery
with a reserve capacity of 154 minutes, at 25 amps, that equals
3,850 amp minutes or 64.2 amp hours. But, the battery is supposed
to be about a l05AH battery! And it is. But at a different amp
draw. You'll seldom have a constant 25 amp draw in an RV. More
likely, you'll have a mixture of high and low draws (microwave
on for several minutes at 80+ amps, pump at 7 amps for less than
a minute, TV at 5 amps fairly constant, a few lights at 5 amps,
etc.). Another major brand of battery, while it doesn't state
"Reserve Capacity," does list on the chart pasted to
it: "25 amps/8 hours." That comes to 70AH, not the
rated 105AH. Obviously, they used different numbers for their
tests. Clearly, the "official" figures quoted by manufacturers
and the charts and typical numbers they use are measured according
to their own boundaries.
In Summary: No battery is going to give you the stated
amp hour capacity. They fudge the figures just as refrigerator
manufacturers do. (A reefer's cubic footage is calculated before
they include shelves, fins, etc.) It's my experience that batteries
are only 75-80% of their rated capacity to start with under real-world
conditions). In use, a battery won't even approach that when
first installed. After a few days of use/charge/discharge it
will build up, but never more than to 80% of stated capacity.
Further, AH is a valueless figure unless they tell you how they
reached it. Look for it anyway, because at least one manufacturer
has "RV/Marine" batteries with more than one AH rating.
If you know the "Brand X l05AH" battery usually sells
for so many dollars and you see "Brand X RV/Marine"
on sale for an unrealistically low price, then they may be peddling
the 90 or 84AH version. Reserve Capacity is a good figure if
they state it. Amp Hour over time charts are not fool proof,
because you don't really know what the boundaries of the test
were, but they are a pretty good way to compare one battery against
another.
Deep Cycling
Let's consider something here: One does not deep cycle a battery
daily as a matter of course. If one did, then the maximum life
of any battery would equal the available number of cycles and
no battery would last more than 6 to 9 months. Ideally, what
you need is a battery (batteries) that will provide the power
you require without being cycled (depleted from resting full
charge) by more than 20 to 50% before being recharged. (If you
have a 100AH battery and take no more than 20AH from it before
recharging, it might last longer than you will.) Unfortunately,
this isn't realistic, but you can take up to 50% from a battery
before recharging and still get long life. Simple arithmetic--how
many AH used versus how many AH available will tell you how many
batteries are needed. Keep in mind that you shouldn't expect
but 80% of the manufacturer's rating. So a 105AH battery is really
about 84AH. MAX! No battery will give you its rated output in
real life! They're rated down to an end point of 10.5 volts.
By then, lights get dim and TV picture small. A Specific Gravity
of about 1.200 or a voltage of 12.25 to 12.3 means the battery
is about 50% discharged. By the time it's down to 11.8 or 12
volts, it's almost dead.
AMP Hours and Battery Capacity
One amp for 100 hours, or any combination, should allow you to
rate batteries, but it doesn't work like that. (It's a logarithmic,
not a linear, progression.) Further, capacity, in AH, depends
on several things: size, amount/type electrolyte, plate thickness,
etc. You don't want to investigate all that crap. Of key interest
to us are:
Rate of Discharge: Generally 20 hours for automotive,
6 for golf cart and 8 for RV/Marine. A 180AH golf cart will,
technically, give you 30 amps for its rated 6 hours, but it will
not give 60 amps for three hours. (Has to do with things like
heat at this higher rate due to extreme chemical action demanded--stuff
you don't want to fool with.) It will give one amp for about
105 hours, though, which is nice to know. Don't just read AH.
Read the charts when comparing batteries.
Specific Gravity: Full charge SG will run from about
1.260 in an auto battery to about 1.275 in a golf cart. High
SG (more acid) allows more juice (current) to be drawn--but only
up to a point; then the battery deteriorates--fast. Golf cart
plates are made to handle this, RV/Marine somewhat, automotive
not at all. Don't try to get more AH by adding acid (or vinegar
instead of distilled water), the battery will just die sooner.
Temperature: Batteries are made to perform best at 77°F.
At higher temps, they put out more, but die sooner. At lower
temps, they put out less, but last longer (unless you let them
freeze).
DON'T FOOL AROUND WITH BATTERY SAFETY
I know from experience. I shorted out a battery. It blew up.
It just takes one little spark. Your face can be horribly disfigured
and you might be blind--assuming you're not seriously killed.
Removing the ground lead first and replacing it last usually
precludes sparks--but not always. Let things air out first and
pay attention. Mark cable ends and terminals as prominently as
you can. Wear safety goggles.
MORE ON SPECIFIC GRAVITY--and checking resting voltage
If you have standard batteries, get a good hydrometer (not one
with colored floating balls in it). It must have a tube inside
with SG increments clearly marked and a built in thermometer
with a temperature correction chart. It's unlikely that a new
battery, even freshly charged, will give more than 80% of its
rated output. You'll get more after it's been used and recharged
a few times--unless it's faulty. Check SG anyway to establish
a "baseline" reading.
Look especially for differences between cells. A variation
of .050 between any means a possible problem. This is after it's
charged and bubbled a bit to mix chemicals thoroughly. If it's
a new battery and this happens, take it back. If old, plan on
replacing it soon. It probably has a stratified/shorted cell.
Initially, there's no need in checking SG until a battery reaches
about 70% of full charge and is bubbling/gassing slightly (not
boiling like a coffee pot). Then, take readings once each hour
and write them down. When three successive readings are alike,
the battery is as charged as it will get. Record readings for
each cell and battery. Disconnect battery from any charge or
load and leave it overnight (24 hours is better). Check SG again.
Readings may be a bit lower, but should be consistent. Record
these as your new baseline: your normal, full charge, resting
values.
Do this again after two weeks or a month of use. Readings
may be slightly higher, but again, should be consistent. If the
batteries have been constantly overcharged or undercharged, it
will show up here. You should have checked that your battery
charger was set properly before starting all this, but if you
get abnormal readings check that your charger is regulating properly
(see later). If you have to add water this soon, you are almost
definitely overcharging. Once you've done the above tests, you
shouldn't have to do it more than twice a year unless you detect
a problem. You should check water level about once a month. Ideally,
you shouldn't have to add water more than two to four times a
year. More than that probably indicates overcharging.
Using a Hydrometer Without Making a Mess
Stick it in a cell until it just rests on top of the plates.
Squirt in and out a few times--gently, don't splatter. Then fill
until the inner tube floats. Too little and it will rest on bottom
of hydrometer. Too much and it will hit the top. In either case,
you'll get false readings. Don't remove the thing from the cell
to read it, you'll just drip acid all over. Take your reading
and write it down. Read at the fluid level, not at the slight
curvature where the fluid touches the inner tube. (Before moving
to the next cell, don't forget to squirt the acid back in.) Note
temperature on thermometer and correct reading as indicated.
Note, again, that all readings for a battery should be within
.050 of each other. Keep in mind you might have a cheap or faulty
hydrometer. El cheapos have a paper SG scale in the tube that
slips up and down.
MORE ON MAINTENANCE
- A properly charged battery should almost never need a baking
soda scrub. If you're not overcharging and spewing acid all over
and if your terminals and contacts have been properly treated
with silicone dielectric, all you should generally need is a
spray and wipe with a household cleaner. Many RV converters aren't
well regulated and do overcharge or undercharge batteries. If
your battery is cruddy, use baking soda and water but don't get
the stuff in the cells! You don't need to slop soda all over
either. Take all the connections apart and clean them. If you
leave corrosion in the end of a wire near the terminal, it'll
just come back. Look closely, if there's white and/or green crud
in the wire and you can't clean it, either replace the cable
or cut off the bad part of a wire and replace the terminal. Use
a battery terminal brush (any auto store) to clean terminal and
cable end.
- Before putting everything back together (you did label everything
didn't you?), coat every single connection with a thin coat of
"silicone dielectric" (any auto store). No, not silicone
caulk or glue! Dielectric is similar to spark plug boot grease
silicone but not as thick and sticky. A four-ounce tube will
cost a few dollars but will last for years. Don't skimp on this
step and don't skimp on cost by substituting Vaseline. (It's
a petroleum product, won't last and makes a mess.) The idea is
to put a thin film on all contact surfaces and not just smear
it over corrosion. Don't use red battery spray! It just makes
a mess. Red/green felt washers are OK. If you do the job right,
you won't need them.
- Add distilled water as necessary. Don't use anything else!
There is no battery magic that will work. Your money will be
better spent on a new battery. Don't underfill; don't overfill.
Wipe up spills.
- To prevent corrosion in wires and cables: Use good stuff.
Skimpy little #4 battery cables from an el-cheapo auto store
won't get it. I have all my main cables made to order by "Wrangler
Power Products." All are #1/0 size (or larger) with sealed
ends to prevent corrosion and are red or black as appropriate.
Terminals applied by Wrangler are highest quality "mil spec"
and match bolts and connectors.
- Smaller wires are done by me. I do not use insulated crimp-on
terminals--way too much line loss and chances for falling apart.
First, strip the end (with the proper tool). Then apply a thin
smear of silicone dielectric and crimp on an uninsulated terminal.
Heat the terminal (carefully so you don't melt the wire's insulation)
and enough silicone will creep into the strands to prevent corrosion.
Continue and apply rosin-core solder. If you practice a little
you'll soon see how to apply just enough heat and solder to avoid
a mess. Then I apply coded wire markers near the terminal (Radio
Shack and others sell them in pages that easily peel and
stick). Lastly, I use adhesive, clear, heat shrink tubing from
Wrangler --not just
regular heat shrink tubing -- to seal the connection and cover
the wire label.
- Before connecting the terminal to a battery or terminal strip,
just a thin film of silicone dielectric is applied to the terminal/lug.
It's not as big a deal as it seems and I do not have any corrosion.
- Do not use in-line fuses or plastic crimp-in connectors that
simply squeeze a sharp prong through wire insulation (the kind
almost every RV shop uses to tap into wiring). All they will
do is cause bad connections and corrode. Splice wires in properly
or, better, install a terminal strip.
METERING BATTERIES
If you have maintenance free (maintenance prohibitive) batteries,
you can't have fun with a hydrometer. Even if you can use a hydrometer,
you don't need to (or want to) do it more than a couple of times
a year. Use the chart (see later) to keep an accurate check on
state of charge. When taking SG readings, measure voltage at
the same time. Keep in mind that if a battery is charging, voltage
will read about ½ to 1 volt higher than actual. Note that
chart voltages (later) are as little as .05 apart. You can't
read that accurately on an analog (dial/needle-faced) meter.
You need a digital meter. You don't need to spend over $200 for
a professional model. See ads in electronics magazines for reasonably
priced meters. You need a 3½ digit" meter (reads
to two decimal places) and get one with at least a 10 amp current
measure (20 is better). At present, the best deal is a Metex
brand #M3800 3½ digit at 20 amp capacity for $40 from:
JAMECO. (See Sources.) All RVers need one of these anyway.
MORE ON UNDERCHARGE AND OVERCHARGE
"Under" results in stratification. "Over"
simply eats the plates. Use a regulator to prevent overcharge.
When you think a battery is charged, too high a SG means over.
Too low means under. Compare with an accurate voltage check.
You should only need to add water a few times a year. More means
battery's gassing too much. You can't tell by feeling the heat
of the battery case any more (better plastics). You must put
about 10% more energy into a battery than you take out (more
high school physics--anytime energy is transformed, there must
be some loss). An "old" battery can require more. Compare
how much you're putting in versus what you take out and size
your system accordingly.
CONNECTING BATTERIES IN PARALLEL, SERIES and SERIES-PARALLEL
This is really simple, but it's amazing how many RVers
screw it all up!
In series, volts increase; amps remain the same.
In parallel, amps increase; volts remain the same.
In Parallel: you connect the (+) of one 12vbat to the
(+) of the other. Connect (-) of one to the (-) of the other.
You will then have still have a 12volt bat, but with greater
amp hour capacity. This is now an ordinary 12V bat, except that
instead of being in one "box," it is in two boxes.
In Series: If you were to hook two 12 volt batteries
in series, you'd have 24 volts. Clearly not the thing to do unless
you have a bus conversion or custom rig that uses 24Volts. However,
many RVers use 6 volt (usually golf cart) batteries. E.G., Two
105AH 6v in series would still = about 105AH but @ a nominal
12V.
Wiring in Series:
To visualize it easier. Start with a simple block diagram. Two
6V batteries.
On left bat, place (-) at left end, place (+) on right end.
On right bat, place (-) on left end, place (+) on right end.
Draw a line from (+) on left bat to adjacent (-) on right bat.
This is now an ordinary 12V bat, except that instead of being
in one "box" with cells all connected in series on
the interior, it is in two boxes joined with a cable. It's still
a single 12 volt bat, electrically, so START THINKING OF IT THIS
WAY and don't confuse yourself by thinking of it as bat 1 and
bat 2.
At this point, you've got two unused bat posts -- just like
an ordinary 12 volt bat; one neg that goes to chassis ground
and one pos that goes to normal 12V isolator/supply/etc.
Series/Parallel:
Just repeat the series step above with two more 6 volt bats and
you end up with two 12V bats. Think of it this way instead of
as four 6V bats! You now have two (-) unused posts. Connect them
together (just as you would when connecting two ordinary 12V
bats in parallel). Repeat for the two unused (+) posts.
It's really quite simple. The problem many people have is
in thinking that this is very complicated. It's not.
The only time you think of the bats as four 6V bats is when
you disconnect them for maintenance and cleaning. And then, only
to make absolutely certain that you don't screw up when putting
them back together.
Toward this end, it's essential that you clearly label posts
and cable ends!
TROUBLESHOOTING
House Battery: The intent here is to determine if the
battery itself is good, and, in its role as a "house"
battery, how you can test it, the house wiring and charging circuit.
Situation: You're charging the battery from any one
of several sources. Everything has been working fine; but for
no apparent reason and all of a sudden, there's no electricity.
Don't just start taking everything apart! Look around for the
obvious. Is the battery still there? Is everything in one piece?
(A nearby lightning strike can blow the top off.) Are the cables
connected? I once spent an hour roaming around with a volt meter
only to find I'd simply left the negative cable off.
Steps:
Connect a volt meter across the battery. It should read some,
reasonable voltage even if well discharged (unless it's dead).
If voltage is adequate, and assuming things are normal, try moving/twisting
the main cable clamps at the battery. Often, even on a clean-appearing
battery, a thin film of corrosion builds up between post and
connector (that you can't see). While the corrosion builds up
very gradually, its effect can happen suddenly.
- Next, especially if the connections are cruddy, place the
tip of an upright, flat-bladed screwdriver on top at the circular
junction of post and clamp and give it a good sock with your
fist (not a hammer).
- Do the same with the other post. If bad connections are the
problem, the above should allow at least some electricity to
flow--enough to indicate the problem. If the above helps at all,
take things apart and clean them.
- If the above doesn't help, first disconnect the charging
source then disconnect the battery (you might as well go ahead
and remove it). Before you start phiddling with the battery,
attach a pair of jumper cables from a known, good battery to
the RV cables.
- Attach the (+) cable first. If you don't let the loose end
touch something, there should be no sparks because there's no
place for electricity to go (yet).
- Then attach the (-) cable to the "good" battery.
(Again, there should be no sparks if you don't screw up.)
- Finally, attach the last (-) end to the RV cable (If the
bad battery was removed, sparks at this final connection shouldn't
hurt anything. This seems like a roundabout way to do all this
but there's a reason for it.
- If there's now electricity in your house, you know you had
a discharged battery. Perhaps a bad battery, but not necessarily.
Again, before you start phiddling with the "bad" battery,
you need to check the charging system. The idea here is find
out why the battery discharged.
- Run a load (lamp or whatever) to remove the surface charge
from your "good" temporary battery. Depending on what
kind of battery charger you have, you may need to run the battery
down to about 13V or less to get the regulator to allow charging
to resume. Keep measuring voltage. When charging resumes, it
will increase.
- If the voltage doesn't increase, it's possible that your
charging source (converter, generator, solar system) isn't working
or the flow is interrupted.
Make the dumb checks first:
- Is the converter working? Is the "kill" switch
on or off on some motor homes? It's unlikely, because then you
should have had a gradual loss, not a sudden one. It is possible
though.
- And it's possible you have a bad battery AND a bad charging
system. RV converters with built-in battery chargers can really
confuse you. There are two outputs to these things: One furnishes
12V direct from the transformer to most house circuits. The other
goes from battery charger portion to battery. If you've been
plugged into commercial power, the main transformer may have
been running everything while the battery charger was not working.
Also, the "kill" switch may have been off or fuse from
charger blown. (Check the dumb things first.)
- Put a volt meter at the battery end while you're doing it.
Quite often, a little manipulating will clear things right up.
If not, go back to the source of the charging system with your
volt meter. Is there power at the charger output? At the output
to battery terminal at solar panels or solar regulator?
- Again, check fuses carefully. You can't tell if a fuse is
bad by looking at it, you need to measure it with a test lamp.
Remember that a meter can indicate "good" if there's
only a slight contact but a test lamp won't work if there's not
enough to carry the load.
- If this also fails, you may have to check at the charging
source with no battery attached. It's easy with an RV converter,
but if you use a solar system or wind generator you may not be
able to (some can be severely damaged if run without a load).
RTFM (Read The F****** Manual)! Our purpose in checking at the
source (with or without battery connected) is to see if there's
anything there.
If there's still no voltage, now starts the onerous process
of checking the whole system.
- Do it logically. Go all the way to the source first. Disconnect
generator, solar panels, whatever, from the system. You can now
measure them in operation without damaging anything (except some
wind chargers). If the charger works, you know that you have
two long pieces of wire (+) and (-) with a problem somewhere.
Don't ignore the (-) wire. It is every bit as necessary as the
(+). Reconnect charger and battery if necessary.
- Go to some logical halfway point with your volt meter. One
way or the other, you'll get voltage (unless you missed something
at the source). Continue in this manner, roughly going halfway
(each time on the dead side). Unless you screw up, you'll soon
isolate the problem to just a few feet of wire. If something
hasn't been left unconnected or the wire been cut, you'll usually
isolate the problem to a connection or fuse.
- Look at things, pull on wires to make sure they're really
attached. This is where bad crimped connections show up. (I spent
an hour helping someone track down a solar system this way. Every
crimped terminal fell apart in my hands. He'd crimped them with
normal pliers.) Look for corrosion at terminals, just as at battery
cables. Remember that just because a converter is buzzing, it
doesn't mean the battery charger is working. If working with
a solar system, never try to put a jumper across the solar (+)
and battery (+) to bypass the regulator--you'll fry it. However,
if you disconnect those wires from the regulator, then you can
put them together.
All the above can be done with a volt meter or test lamp.
In fact, a test lamp works better at continuity checks, because
a volt meter might indicate power if only one strand of wire
is still connected while a test lamp won't light if it doesn't
have a circuit heavy enough for the load.
TO CHECK THE BATTERY ITSELF--MORE ON RESTING VOLTAGE
It can be checked with a hydrometer, but a battery can
read OK and still be faulty. Here's a good way to check a battery.
It takes time, but it's worth it:
- Charge it fully, preferably with a good battery charger or
an independent, manual, automotive charger (you need one anyway
for emergencies). This can take awhile if it's been deep discharged
(dead).
- Measure voltage. It should be quite high--over 13 volts and
14.+ is better. Disconnect the charger. Leave the battery (with
nothing connected to it) at least 6 hours. Overnight or 24 hours
is better.
- Measure voltage again. It should be 12.6 volts. If not, even
if it's 12.5, it's a goner or it's going. If it reads 12.6, it
still might be bad.
- A commercial battery shop can check this with a variable
load tester. So can you. If the battery is at least a so-called
l00AH RV/Marine type, it should start most engines in decent
weather. Connect a volt meter across it. If it doesn't start,
jump start it. Run the engine at a nice, fast idle (1,500 to
2,000 rpm).
- If the voltage rises to over 14 volts in only 4 or 5 minutes,
you have a bad battery. Due to things we won't dwell on here,
the AH capacity has been severely reduced (stratification, deep
discharges, etc.). What you have is a battery that has about
a l0AH capacity instead of l00AH. It tests OK because it has
some capacity (might run a lamp a few hours), but not enough.
This common problem often drives people nuts. It tests OK, it
just won't last long.
- The same test works on auto batteries. They test OK but won't
start an engine.
SHORTS/DRAINS/LEAKS
Actually, they rarely occur. What most people think is a short
causing their battery to go down overnight is really the l0AH
condition described above, a bad charger (or problems in associated
wiring or contacts) or a hidden load. The most common hidden-loads
are gas leak detectors with automatic LP shut off, inverters
left on and faulty trailer breakaway switches (common). It is
possible, though, to have a short. A bad one will usually repeatedly
blow fuses (or start a fire--so do not just put in a bigger fuse).
The most common, and hardest to find and fix, is having run a
screw through the skin where it penetrated wires or connected
(+) to skin or frame. The contact can be so slight it leaks to
ground without visible results.
Easiest way to check for a short
Disconnect the charging source and disconnect the positive cable
from the battery to the RV system. Attach a volt meter positive
(+) probe to the battery (+) post. Attach the voltmeter negative
probe to the end of the (+) cable that you removed from the battery.
Switch off disconnect/unplug everything in the RV that uses 12V
electricity. Don't forget clocks, TV amplifiers, refrigerator
"brain" (reefers with circuit boards use 12V to run
the circuit board even when operating on 120VAC or LP), and such
at water heater and furnace also. Also shut off converter (or
disconnect from commercial power). If you've really disconnected
everything, your volt meter will read zero--unless there's a
short or hidden load. With a digital meter, you may read a thousandth
of an amp or so--no problem.
To check, turn on one lamp. The volt meter should read battery
voltage, but the lamp should not come on. To check further, shut
off the lamp and replace volt meter with your 12V test light.
If it comes on, you have a short, hidden load or forgot to turn
something off. Before you start tracking wires down, go to your
fuse panel and remove fuses one at a time until you isolate the
circuit or circuits at fault. This can be tricky if your system
has been modified. Look for add ons (like two wires connected
to one fuse) or isolated fuses tapped into battery charging line
and similar.
Once you have the circuit isolated, you can reconnect the
(+) cable at the battery and move to the fuse panel. If you haven't
a diagram showing what's on that circuit, you can energize all
the others and see what doesn't work in the RV. (You should have
a diagram of every RV circuit and all wires should be labeled.
It's the only way to keep things from getting screwed up.) Leave
the fuse out of suspect circuit and, instead of using a volt
meter, use an ammeter (of at least 10 amps) connected in the
same way. With everything on the circuit off, there should be
a zero amp reading. If there is a reading, then you have a short
or hidden user. Remember, though, that things like breakaway
switches are often unfused and unprotected (because it's so important
to be able to stop). When checking these type circuits you may
have to disconnect the wire.
TROUBLE SHOOTING ENGINE ELECTRIC and STARTING BATTERY
Starting Battery: Similar to the "house battery"
checks. It works well, then all of a sudden, nothing or just
a clicking of the starter solenoid. Again, don't just start taking
things apart! Do the dumb stuff first: Did you leave the lights
on? Is the transmission selector really in park? Twist cable
connectors as in house battery. If it even tries to start, you
probably just have crummy connections. If you got nothing, not
even a clicking solenoid, don't forget to check the "ignition
tag" wire. From the coil to the solenoid, there is a small
wire that only allows the solenoid to operate when the ignition
is turned on. This wire, at the coil end particularly, is often
connected with a slip-on connector that is easily dislodged when
checking oil and such (and often is so loose it just falls off).
If corroded connections were the cause, and twisting/scraping
got the thing going, go home and clean things up. When doing
so, closely examine cable ends for crud as with house battery.
Hard-start-when-hot is common to many engines. People build metal
shields or buy those especially made, wrap starters in asbestos,
point fans at them, buy racing car starters and all sorts of
things to correct the problem, when in many cases all they needed
was heavier cables. All the cable electricity must make a complete
path: from battery-to solenoid-to starter and the ground cable
must be properly connected also. Most Big A and similar good
auto stores carry heavy stuff for trucks. Better, get cables
from Wrangler.
Even if corrosion was the problem, if it's been going on for
some time, you may have had a continuous undercharge. The battery
may just be low, or ruined. You can't test it properly until
it's been fully charged, so get the thing started with a jump
start if you have to and go home. Clean things up, charge the
battery with an independent charger and test as you did the house
battery. You can't do it properly in the street. A service station
will just sell you a new battery--needed or not.
JUMP STARTING THE SAFE WAY
It may seem like a pain in the ass, but it's better than acid
in the eyes--or worse. Remove caps from the "dead"
battery if possible. In winter, check for ice in the battery
(if you can). Don't ever try to jump a battery with ice in it.
It'll blow almost surely. Cover cap holes with a damp cloth (but
don't short out the terminals). Connect a jumper cable from the
(+) post of one battery to the (+) post of the other. Connect
the (-) cable: First to the (-) post of the good battery. Check
that all extra accessories are turned off, then start the engine
of the "helper" vehicle. Only then should you connect
the last (-) to the bad one. Don't connect it to the (-) post,
but to an engine bolt at least a foot away (so any sparks will
be well away from the battery itself. If the problem was due
to your battery, the thing should start. Remove the (-) cable
from the engine bolt first, then the rest in reverse order from
the way you hooked them up to ensure against sparks.
If it's running, and alternator/regulator are OK, you no longer
need a good battery to keep it running unless you let the engine
die. Electricity from alternator feeds the whole thing. You do
need a battery connected, though, or you'll burn up the alternator.
The thing to do is go home, if possible, or to a shop if you're
so inclined. In either case, the main thing is to find out why
it happened, not just start replacing things.
If the starter wouldn't turn, the problem is probably between
the starter and battery, but not necessarily. The ignition tag
switch mentioned above is a very good bet. So is the neutral
safety switch on most vehicles. Also, some won't start if seat
belt interlocks aren't in place, or are disconnected. Look closely
at wires to/from the ignition module as well. Some can melt and
short if near manifolds. More often, and common with hot RVs,
is the wire insulation bakes slowly over time and crumbles off.
The bare wires will then short out. It's maddening when they
do this intermittently (touch each other only when driving as
wind and vibration jostle them). Usually, you'll get a clue that
this is happening because it'll only occur, initially, as a slight
"miss." Don't ignore clues! If something is acting
a bit odd, get it checked out before it quits.
If the thing won't start with a jump, and you're in a bad
place (like blocking the pump in a service station), you might
be lucky and they'll shove you out of the way so you can try
the tests above and expedients below. Often, they'll just call
a tow truck and drag you away whether you like it or not. It
really is a good idea to subscribe to one of the major road emergency
services like those of Good Sam or Escapees. (Not just some free
or el cheapo like AAA.) Further, the newer vehicles are so complicated
there's very little you can do anyway. And diesels are another
animal. Trailer Life or Motor Home had a couple of excellent
articles on the limited things owners can do with diesels. You
should write them and get reprints (or check any number of web
sites) before you need them.
Prevention is most important and most ignored. Be alert for
odd noises, "misses" and such. Look under the hood.
Check things. Not just oil and water. Probe around wires and
check belts and hoses. Replace them every couple of years. (If
the old ones are still OK, keep them for spares.) Check tire
pressure, don't just kick them. Check brakes and fuel lines.
Peer under the rig, with engine running, and look for leaks.
Connect a volt meter across your battery, then start the engine
and make sure voltage increases. Change oil at a place that will
let you go down in the pit and look at all the junk on the underside.
Do similar with your "house" equipment. Spending months
at a park with a hook up is nice, but once in a while you need
to disconnect and run self contained for a day or so.
DOING IT YOURSELF
What follows is for those so inclined or in a desperate situation
in the middle of nowhere. Here are some things you might try
to get it to start even if it doesn't want to. A lot of this
requires two people. Tell each other when you get ready to turn
something on and be careful doing this!
First things first. It's nice to have a full set of
service manuals, but they'll cost over $150 in most cases. They'll
also include a lot of tests that can only be made with the specialized
equipment at a dealership. In almost every case though, since
the 70's, the set includes an electrical and vacuum trouble shooting
manual that can be bought separately and includes all sorts of
tests and pictures. Call "Helm, Inc." (see sources)
and get this one at least. Helm is mostly for "domestic"
vehicles. The (800) number for customer service at most importers
will eventually get you to someone that handles their manuals.
At Toyota, I asked for the owner's manual (no charge), then asked
for elect/vacuum/etc., manual ($15 and it's very excellent).
If you can use the internet, go to a good search engine (Google
the best) and use the "advanced search" option to type
in exact phrases. It's amazing how much info is out there!
Starter won't turn. You've made the checks above. Connect
a volt meter to the small ignition tag wire at the solenoid.
If there are two, one is a ground wire, you might have to try
the other. Turn on ignition and you should read volts. Check
that solenoid is grounded either through the mounting bolt on
a single-tag model or second line on the double-tag model. Recheck
ignition tag at coil. Disconnect it and turn ignition on. Measure
volts at wire end to see if anything is coming from ignition
switch. Also, is it getting to the ignition switch? People who
leave a large bunch of keys hanging in a switch can wear out
switch contacts. If electricity is getting to the solenoid, either
from the above (or from a jumper right from the battery post),
and starter won't turn, and there is 12V at the big solenoid
post that comes from the battery, connect a jumper cable (not
just tiny wire) across the two big lugs at the solenoid. Careful,
you're bypassing everything and if starter is good, it should
turn.
Some vehicles have two solenoids: One near the battery
and another at the starter itself. If you bypass the first, as
above, and the starter still doesn't turn (assuming a good battery),
then the problem should be in the cable from solenoid to starter,
the starter itself, or the solenoid at starter. The fastest way
to find out is hook up the jumper cable to the (+) terminal at
the starter. Then crawl out from under there and connect the
other end to the battery (+) post. Be prepared to immediately
disconnect the jumper end at battery (+) during this step. If
ignition was turned off, disconnecting will stop everything.
If in run, and the engine starts, you'll want to disconnect to
keep the starter from turning with engine running (ruin). All
the above can be tricky and dangerous so if you don 't fully
understand it, have someone show you how to do It before doing
it for real.
Once you've done all the above, you should pretty much know
what's bad. Unless you overlooked something, about all that's
left is a burned out starter or the linkage to the engine's flywheel
(in which case you should have been able to smell the trouble).
The final way to check the starter is take it off, lay it on
the ground (with foot holding it in place) and attach a set of
jumper cables from the battery (be careful). All this will allow
you to isolate problems. You should have a second battery in
your vehicle anyway. Also a spare starter, solenoid, (and voltage
regulator, alternator and ignition module too). Fuel/ignition
problems wouldn't have kept the starter from eventually turning
(even if engine didn't start).
FAST ALTERNATOR/REGULATOR TEST
For vehicles with a separate regulator, like Ford:
Measure battery volts with everything off (BASE). Measure volts
with engine running at about 2,000rpm and all accessories turned
off (NO LOAD). Measure volts at same rpm with headlights and
heater blower on high (LOAD). If NO LOAD is 1 to 2 volts higher
than BASE, and LOAD is at least 2 volt higher than BASE, both
regulator and alternator are OK. If both LOAD and NO LOAD are
higher than BASE, alternator must be working. (But may be too
skimpy for your RV. Extra running lights, video rear view systems,
lights on toad cars, etc., can really load an alternator. So
much so that it can't produce enough to keep up. Even factory
high-power alternators aren't enough--since they're made as cheap
as possible (check with "Wrangler"
for one that won't poop out). If NO LOAD is much more than 2
volts higher than BASE, check regulator ground (mounting screws)
and repeat test. If still over 2 volts, disconnect regulator
wiring plug and repeat test. If volts drop to BASE, replace regulator.
This is a partial and typical test. A factory trouble shooting
manual should include tests for yours.
I hesitated to describe some of these tests because differences
in vehicles can screw things up. Get the right book for yours.
I've left out the simple stuff on checking for spark and fuel
(when starter turns but engine won't start) because all trouble
shooting books have that. GM electronics can give you a fit;
but, as a wise, old RVer says, "Get a GMC and you get what
you deserve." (Nowadays, all electronics can give you a
fit.)
DUMB TESTS
From the term Durbert Dumbutt--stereotype of the average RoVer
(this is not really a derogatory term):
- When something goes wrong, don't just start taking things
apart. Look for the "dumb" stuff first. There's an
expression: "Don't just stand there, do something."
At times, it's wise to "Don't just do something, but stand
there -- and think."
- Check the simple things first. If your car won't start is
the battery still there -- or stolen by a druggie?
- Men, listen to your wife. A friend described a bucking, misfiring
engine. He pulled off and got tools and meters and started dismantling
things and checking them. His wife kept trying to ask a question.
He told her to go make coffee. What she was trying to ask was
why one of the ignition wires was hanging loose.
Make the Durbert tests first. Performance is sluggish.
Tuneup? Why not check for dirty air cleaner first? Bog down on
hills? Lots of reasons, but check air cleaner and fuel filter
first. Transmission slipping? Might be expensive. But might be
as little as ½ quart low on fluid. First add fluid, then
find out where it's leaking, then get it fixed. Ammeter not working?
Smoke from under hood? Burned alternator? Maybe. But maybe just
a loose belt. Standing along the highway creates confusion and
stress. Get a simple, trouble-shooting guide and do things logically.
BATTERY ISOLATORS
Almost everybody has one. Most people never pay attention to
them. I do. And I've got mine remoted to a switch on the dash
to avoid the [many] problems they can cause. Most isolators send
a charge to the batteries automatically. I don't want to do that.
Normally, my solar system keeps the "house" batteries
charged just fine. There are times, in bad weather, when I need
to boost the batteries, so when on the road I hit the switch
that goes to the charge line to house batteries and the engine
alternator charges them in the normal way. A cheap, voltmeter
on the dash keeps me informed when to shut charging off.
SOURCES AND REFERENCES
You can get factory manuals from the factory but it's a chore.
Call "Helm, Inc." publication div. (800) 782-4356.
Get the order sheet for your vehicle. It will list all the pubs
available. Don't confuse them with the name of your motor home,
but tell them the chassis stuff. ('92, Ford, E-350, etc). Also
note other sources for manuals and info above.
Contact "Technical Service Publications Service Manuals."
3000 Schaefer Rd., P0 Box 1902 Room 2004, Dearborn, MI 48121-9973.
Ask for "Motor Home Service Guide." (Might not be valid.)
For GM try "Chevrolet Customer Assistance Center."
5505 Corporate Dr., P0 Box 7047, Troy, MI 48007-7047. (800) 222-1020.
Ask for the "Chevrolet Motor Home Service Guide."
Battery chargers: The best you can buy are made by
"Ample Power Co." 2442 NW Market St., #43, Seattle,
WA 98107. (800) 541-7789 (see Sources).
They specialize in equipment for ocean-going boats so what they
make is ultra-reliable and ultra-expensive. They also publish
two books: "Living on 12 Volts with Ample Power" ($25)
and "Wiring 12 Volts for Ample Power" ($20). Primarily
for boats, but with 12V info not available elsewhere. "Living"
has lots of info on refrigeration. "Wiring" has what
you need to know. I consider both essential. Read these and find
out how cheezy RV converters really are. Also available from
Amazon.
Quality battery chargers also available in boating stores
(see West Marine below), alternative energy stores (see
Backwoods Solar below) and a very few, good RV stores.
Look for user-adjustable voltage settings. Cost minimum $250
and up for good ones. The best stand-alone (independent) battery
charger currently available is the "True Charge" model
made by "Statpower." If getting a big inverter anyway,
consider one with battery charger option -- a top quality charger
that would cost much more as a stand alone.
"RV Power Products" 1058 Monterey Vista Way,
Encinitas, CA 92024. (800) 493-7877 (www.rvpowerproducts.com).
Their "solar" regulator/chargers are the best you can
get for an RV.
Tying it all together.
Cable, wire, switches, fuse blocks. High-output, reliable alternators
that won't crap out the first time you use them, adjustable voltage
regulators plus much more are available from "Wrangler
N. W. Power Products" 4444 SE. 27th Ave., Portland OR
97202. (800) 962-2616. (www.wranglernw.com)
Free catalog. I use them exclusively. Top quality.
Solar electric stuff + More: If you're interested in
solar systems, inverters and other innovative devices, the prime
source for RVers is "RV Solar Electric." Subscribe
to their free newsletter. Buy their "Rver's Guide to Solar
Battery Charging." Get their "Installation Guide"
($5 refundable with purchase) even if you buy equipment elsewhere
because it has info that no one else provides. 14415 N. 73d St.,
Scottsdale, AZ 85260. (800) 999-8520. (www.rvsolarelectric.com)
This is a great info source. Reliable people who won't mislead
you or rip you off. There are a lot of sharks out there selling
solar products, inverters, etc., at "dealer cost + a few
pennies" and similar nonsense just to try to shaft their
competitors. But when you're in trouble, they're no help. RV
Solar Electric will help you. Nice people who are interested
in the long term, not the short term profit. I use them almost
exclusively.
Batteries: RV Solar Electric will be glad to answer
questions on gel cells and such and refer you to a reliable dealer.
West Marine is very competitive in alternative batteries also.
Golf cart and fork lift batteries are better bought (and cheaper)
from a "regular" battery store than an RV store. Best
source for AGM batteries is "Backwoods Solar."
Boating Stores: Many, like RV stores, sell crap at
inflated prices. Good, big ones carry alternators, regulators,
isolators, etc., of far better quality than RV stores. The best
is "West Marine" P0 Box 50050, Watsonville,
CA 95077-5050. (800) 538-0775. (www.westmarine.com)
Huge catalog (5$ refundable -- but they'll send one free if you
whine a little) has page after page of buying advice, product
comparisons and tips. Most highly recommended.
Meters: "JAMECO," mentioned in this poop
sheet, is my preferred source for meters that will do what RVers
need at a reasonable price. 1355 Shoreway Rd. Belmont, CA 94002.
(800) 831-4242. (www.jameco.com)
Their Metex Brand #M3800 $40 Jameco part # 27115, digital meter,
with volts to two decimal places and current measure to 20 amps
is perfect for RVs.
For the latest info on alternative energy: "Home Power--The
Hands-on Journal of Home-Made Power" $22.50 per year
(for 6 issues of well over 100 pages to US. Zip codes 2d Class)
or $36 for 1st Class. P0 Box 520, Ashland, OR 97520. (800) 707-6585.
(www.homepower.com) has
current issue free. Also on news stands. A must have for people
interested in alternative energy. What's new, what really works,
hi-tech and low yet they never "talk down" to you.
This is an absolute MUST-HAVE reference for RVers. "Managing
12 Volts: How to Upgrade, Operate and Troubleshoot 12 Volt Electrical
Systems," by Harold Barre. Some book and RV stores ($13.97
from Amazon) 219 pages. The best book ever published on this
subject.
"RV Electrical Systems" covers both DC and
AC systems and is another MUST HAVE. Extraordinary detail without
getting into engineering. Covers things nobody else does. By
Bill and Jan Moeller, Some book and RV stores ($15.37 from Amazon)
265 pages.
BATTERY CHART
What percent of charge is equivalent to what specific gravity
and how gel batteries state of charge relate is debatable. Everybody
has their own opinion and many of the experts disagree. The chart
below is only my opinion, based on many such charts, some very
sophisticated tests involving elaborate equipment by others and
my own "real RV world" tests using a variety of meters
available to any RVer as well as an extraordinarily-accurate
monitor/controller from Ample Power tied to a computer. Laboratory
tests use electrical loads that simulate the real equipment.
My tests used real-world RV equipment under normal living conditions.
Differences in my tests and yours might involve: The fact that
my meters were all calibrated to an accurate master reading.
The amp draw of my loads being measured rather than extracted
from a label, etc. Regardless, your readings will be accurate
for your system (though you might come up with slightly different
numbers). I encourage you to make your own measurements and write
in your own numbers.
|
% Of Charge |
Standard Battery
Typical Specific Gravity
(After Temperature Correction) |
Standard Battery
Equivalent
Resting Volts |
Gel-Cell Battery
Equivalent
Resting Volts |
|
100% |
1.260 (auto) to 1.280 (industrial) |
12.60-12.75 |
12.90-13.00 |
|
95% |
1.255 |
12.60-12.70 |
12.80 |
|
90% |
1.250 (Resting S.G. for standard RV battery.) |
12.60-12.65 |
12.70 |
|
85% |
1.245 (Same as above. No point being too picky.) |
12.60 |
|
|
80% |
1.235-1.240 (We try not to discharge below this
point.) |
12.50-12.55 |
12.60 |
|
75% |
1.225-1.230 (1.230=minimum SG for a charged battery.) |
12.50 |
|
|
70% |
1.220 (Anything below 1.220 is "poorly"
charged.) |
12.45 |
12.50 |
|
65% |
1.215 |
12.40 |
|
|
60% |
1.205 |
12.35 |
12.40 |
|
55% |
1.200 |
12.30 |
|
|
50% |
1.190-1.195 (Try to never discharge below this
point.) |
12.25 |
12.35 |
|
45% |
1.185 |
12.20 |
|
|
40% |
1.180 |
12.15-12.20 |
12.25 |
|
25% |
1.160-1.170 (Dangerously low; battery being damaged.) |
12.10-12.15 |
|
|
20% |
1.150 (Cells die soon at this point. Bye-bye
battery.) |
11.80-12.00 |
12.15 |
NOTES:
- Keep in mind that listed voltages are "Resting"
Volts.
- Maintaining an 80% State Of Charge, when the battery is in
use (under load), is a goal. It can't be maintained for long
without some form of charging taking place. A converter or independent
battery charger (assuming they're working properly) will do this.
So will an adequate Solar Electric System. A generator won't
do this well at all--it would need to run constantly or be repeatedly
started and stopped -- not too practical.
- However, maintaining a 50% State Of Charge should be no problem
and battery will not be damaged at all. (See Management) In this
case though, a generator could do the job.
- The cautions in the Specific Gravity column pertain to batteries
that are left at this level (or that continue to be used) without
charging. It is not uncommon, under a heavy load, for batteries
to drop to this level temporarily. It's only when your battery
is not being charged and under load that the 25% and 20% State
Of Charge cautions indicate a damaging deep cycle.
NOTES BASED ON RVer's QUESTIONS AND COMMENTS
No, this is not a book. It's not intended to be. (Any book is
outdated months before it's ever published. It's stuff everybody
assumes you know, so they never bother to tell you about it.
The Ample Power books are excellent. Some of the installation
guides that come with purchases include a wealth of info. RV
Solar Electric, Trace, Heart Interface and Statpower inverters
are examples.
"HYPE" is more prevalent in battery manufacturers
statements than in any other area of RVs (a field that's renowned
for excess hype). Distributors and dealers add their own baldly
exaggerated statements and just make things worse. You have to
use your consumer skills and weed out the BS. My description
of battery types in this poop sheet should help you avoid all
that nonsense.
The "big" names in batteries are all about equal.
Moreover, they have their batteries in stores literally everywhere
which makes for EZ returns when you're on the road. Trojan, Exide,
Interstate are the most common. Keep in mind there are only about
six major manufacturers of batteries in the U. S. (at this time).
Many of the batteries you see in stores are made by these and
have "house" labels. Nothing wrong with that if you
know how to evaluate what you're getting. (You can put your label
on batteries too, if you buy enough of them.) Why, then, don't
I recommend Delco (made by GM)? Because many of their innovations
are not well thought out in my opinion.
Gel cell and AGM batteries are another exception. As
mentioned earlier, some manufacturers are trying so hard to compete
price-wise that their batteries are "light weights"
(literally and figuratively).
There will be great advances in batteries pretty soon.
Along with that will come a lot of really nutty stuff. Be careful.
If you can't find "uninsulated" wire terminals in
the proper size, get insulated ones and cut the insulator off.
It's EZ. A few scores from front to back with a sharp knife,
then twist it off with a pair of pliers. If you don't want to
bother with all that solder stuff, at least get a pair of professional
electricians crimping pliers (the best make a double crimp, won't
release until the crimp is sound, use a ratcheting mechanism,
etc., Cost about $50). You'll be better off crimping and soldering.
Don't economize with solid-copper household (Romex or UF)
wire in an RV. It doesn't make full contact at terminals (resulting
in heavy voltage drop) and will bend and flex so much that it
will break or come loose. Use stranded copper wire. Protect all
wire where it comes in contact with sharp edges. DO use appropriately
hefty wire and cable and DON'T use skimpy stuff.
What do I use in my RV?
Former motor home had solar array of 13 panels. Divided into
two systems. One, with 4 PV modules, feeds 2 gel cells and inverter
with battery charger for audio/visual stuff and uses RV Solar's
"Solar Guard" regulator. The other, with 9 PV modules
feeds 4 gel cells and large true-sine-wave inverter with battery
charger, for computer and house RV stuff like microwave, heavy
tools, etc., and uses a "Solar Boost 50" from "RV
Power Products" regulator (the best you can get). The systems
can be tied together with switches or charging can be switched
from one to the other. Inverters are manually switched or plugged
in. I don't rely on automatic transfer (relay) switches that
can hang up. I keep a standard automotive battery charger in
case of emergency. I do not use standard RV appliances (reefer,
freezer, furnace or water heater). See Sources
and Resources. Current, smaller mini-motor home is similar
to above but with smaller solar system and battery bank. |
