Some general hints for desulfating various sorts of lead-acid batteries
The following will help to get the most out of desulfation efforts:
- The chemistry of desulfation processes speeds up at higher temperatures. If possible, heat the batteries to 40-50 degrees C for best results.
- If batteries are heavily sulfated, an initial treatment with EDTA is recommended, followed by pulsing.
- Although gel cell batteries are apparently sealed, they still dry out with time, and must be refilled to bring them back to life. In order to rehydrate them, they must be carefully opened and distilled water dripped into the vent holes. This procedure will vary depending on battery type. On the batteries I tried (made by CSB), it took about a minute to pry off the plastic lid over the vent holes, and remove the caps. It won't take much to rehydrate the gel material, in any case standing water in the cell will eventually go away. Note Oct 2003: The consensus of opinion from the BBS postings is that these types of batteries are just not generally recoverable, and are not much helped by pulsing, especially if they are at all old.
- Several cycles of pulsing, charging and discharging are needed to show results. It is recommended to try long periods of trickle charging with the desulfator, and shorter discharge periods to determine progress.
- It is often the case that one cell is worse than the others. If there is a shorted cell, there is often no way to recover the battery, and charging attempts will usually just heat up the good cells.
- The fast rise time pulses that the circuits in this web site produce require that short, fairly heavy wire or shielded cable be used to connect to the battery terminals.
- Multiple batteries can be desulfated in parallel, but the progress will be slower. Results can be seen in some cases in a week, but might take as long as a month for full recovery.
- Excessive pulse amplitude for a given battery size can cause "shedding", or the driving off of active plate material in relatively large pieces, something to avoid. This is not likely a problem unless a small gel cell battery is used with a large pulser.
- Connecting other equipment across the battery to be desulfated is not necessarily a problem, but in some cases the loads might shunt away some of the pulser's output. While most unfiltered battery chargers present a high impedance to the current pulses, such things as inverters might not. In such a case, place a choke in series with one of the inverter leads to eliminate the problem. This can be a simple ferrite toroid with one or two turns wrapped around it.
This page will be updated as more results come in. Let me know, and I can place your data here.
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