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in Humboldt County, California

June 2024

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Using a battery desulphator

A battery desulphator is a device that is primarily meant for preventing the build-up of sulphur precipitate inside of a lead acid battery. Sulphation is common in lead acid batteries, particularly if the battery has been left unattended for an extended period of time. There is also a possible benefit from using a desulphator on healthy batteries or batteries that have reduced capacity from age. I recently tried using desulphator on my aging pack of US-2200 batteries.

The desulphator I used is a Solar Converters, Inc model BD-2 that I borrowed from John Schaefer. This particular model can be adjusted to work from 10 to 60 volts and according to the label draws about 50mA. Since my batteries are 6 volts, I had to use two batteries in series to operate the desulphator. This was not a problem since I could easily find two adjacent batteries in my pack that had suspicious readings on the volt meter and hydrometer. I left the desulphator on for over 24 hours, while a small power supply provided a trickle charge of about 2 amps into the batteries.

After running the desulphator and the charger for several days on four different batteries, I checked the readings again. One of the batteries that had previously had poor readings seemed to be much better, while another battery did not seem to improve at all. It is hard to say whether the desulphator made much of a difference, but it certainly didn't do any harm!

In order to see what the desulphator was doing, I hooked up my oscilloscope while it was operating. When I took a direct reading of the voltage, nothing was visible on the scope, but by hooking up a small length of wire as a shunt, I was able to see the current. The wave form appeared to be a sharp spike followed by a small "bounce."

The frequency of the waveform was approximately 1kHz. I would speculate that the desulphator is best at it's intended purpose of preventing sulphur build-up in battery cells. In the case of my aging batteries, I think the desulphator may be somewhat beneficial, but the batteries are nearing the end of their life cycle, and it is unlikely that anything can delay their impending failure.