[Ares-races] RE: ARES-RACES - Batteries

[Rane Curl]

On Mon, 2 May 2005, Dave Colter wrote:
>
> Hi David,
> I use hundreds of these every year in my business. Assuming they are still
> OK, they should work fine for shack backup use. Try putting a load on them
> for a few minutes and watch the voltage. If it drops quickly below 11 volts,
> they are worn out. SLA batteries typically have a working life of 3-5 years.
> Charging is easy. Just feed them about 14.5 volts. Any more, and you'll
> charge them too fast. SLA's don't vent the hydrogen sulfide gas that is
> generated when you charge them. The batteries develop an internal pressure
> of a few pounds that causes the gas to recombine with the electrolyte. A
> higher voltage will cause the battery to generate gas faster than it can
> recombine, the battery will overheat, swell up, and warp the plates, leaving
> you with a nice doorstop.

All good advice - except that the gas is hydrogen, not hydrogen sulfide.

I recharge gel cells from a 13.8 V regulated supply, and use a small light
bulb to limit the initial current to .1 battery VA. The battery, if OK,
cannot overcharge on this - the battery can even be left floating on it.

--Rane, N8REG