Lead Acid Battery Desulfation Pulse Generator

Some help and information for builders

Here is the circuit for use in 24 volt systems. It uses the same topology as the 12 volt unit, but adds a regulator to drop the voltage down for the 555.

• The value for L3 is higer than in the 12 volt circuit because the 555 timing constants are the same. But one could use a lower value at L3 by reducing the 555 pulse width.

• For yet higher voltages, the same basic circuit is used, but care must be taken to increase R5 so that the regulator input voltage is dropped sufficiently. If the 555 timer pulse is unchanged, then one would try something like 470uH for a 36 volt unit, and perhaps 680uH for a 48 volt unit. L2 would be doubled as well. The pulse width will still likely need to be adjusted for best peak current vs. total circuit current demand. (These two are a tradeoff.)

• The P channel MOSFET can be any unit that has a sufficiently low "on resistance" rating. Power dissipation is low, but I use a high power unit to lower this resistance, as that is part of what limits the peak pulse current generated. The voltage rating needs to be high enough to stand the highest peak voltage, which might get to be 100 volts. If you want to try for higher peak currents, you can parallel MOSFETS together, as they share current well.

• For systems with 120 volts, the same approach can be used. But Q1 will need to be tested for high voltage, and likely need heat sinking, as the pulse width will need to be increased sufficiently to get the high peak current required.