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From: raoul@eplunix.UUCP (Nico Garcia)
Newsgroups: sci.electronics
Subject: Re: Batteries!
Keywords: nicad gel cell
Message-ID: <985@eplunix.UUCP>
Date: 10 Dec 90 06:49:50 GMT
References: <5664@uafhp.uark.edu>
Organization: Eaton-Peabody Lab, Boston, MA
Lines: 22

In article <5664@uafhp.uark.edu>, bbs00068@uafcseg.uucp (Joel Kolstad) writes:
> GelCells -- Apparently partially damaged is overcharge too much or deep 
> 	cycles more than a few times.  However, DON'T form memories.  Hard
> 	to charge properly -- require a regulated charging.  Considering
> 	that, I'd have to have a circuit powered by the batteries just to
> 	recharge the batteries. :-( This means that if the batteries ever
> 	get so low of a charge that I can no longer power the regulator
> 	circuit, the batteries will probably stay discharged!  Arghh...
  

Hmmm. I won't address your NiCad questions, since I've never worked with 
those directly. However, for a Gel-Cell charger, use a LM317 rated for
your maximum voltage from your power supply to provide a regulated 
charge voltage, and drop a resistor on the output of it to limit the current
to your batteries. You only need a trickle charge anyway, and a 12 Volt
supply, even if you put the battery in backwards, will only put a 24 Volt
drain on it. Put a 1 K resistor there, and a diode to stop discharges,
and you win.
-- 
			Nico Garcia
			Designs by Geniuses for use by Idiots
			eplunix!cirl!raoul@eddie.mit.edu