[Shop-talk] Battery charger

[Randall]

> I know the hard-core battery types laugh at the idea that what these 
> chargers do is really 'desulfating' but it does seem to work, 

FWIW, I just recovered 2 AGM batteries and a 12v gel pack that were badly sulfated, using a very simple home-brew "desulfator".  I
honestly did not think it would work, but I'm 3 for 3 and working on the 4th as I type.

The "desulfator" is just a single diode (half wave rectifier) and an incandescent light bulb, in series.  The diode supplies
essentially 16ms pulses, while the bulb limits the current.

All of the batteries initially went up to around 60 volts (indicating very high internal resistance and severe sulfation), then
after a few days dropped to well below 12v.  After 3-4 days, I switched to an ordinary unregulated charger for about 10 hours.

Haven't done a real load test yet, but after loading one at about 5 amps for about an hour, the voltage was still around 12.8.

Randall