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From: rees@apollo.uucp (Jim Rees)
Newsgroups: sci.electronics
Subject: Re: NICADs
Message-ID: <37043f5d.b8ab@apollo.uucp>
Date: Tue, 1-Sep-87 08:39:00 EDT
Article-I.D.: apollo.37043f5d.b8ab
Posted: Tue Sep  1 08:39:00 1987
Date-Received: Sat, 5-Sep-87 02:26:52 EDT
References: <646@gec-mi-at.co.uk> <36f19f36.b8ab@apollo.uucp> <1762@sol.ARPA>
Organization: Apollo Computer, Chelmsford, Mass.
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    Won't a great deal of heat result in a 1C charge for 16 hours?  Won't this
    heat result in a possible exploding battery or at the very least a damaged
    battery especially if the battery is not vented?

Sorry, slip of the keys/mind.

.1C (one-tenth C) is the max safe charge rate without overcharge detection.
The standard charge is .1C for 16 hours, which allows for a full charge
even at a very low efficiency.

I've seen quick chargers go as high as 10C, but you'd better have some
pretty sophisticated full-charge detection circuitry at this rate.

    If you have a battery pack that has four cells and one of them has accidently
    been reversed charged, or internally shorted as you say, when these cells are
    fully charged what will the shorted cell read on a volt meter?

If you burn off the short first, it will be 1.2 - 1.25, just like a normal
cell.  If you don't burn off the short, it won't take a charge at all,
and even after 16 hours of .1C it will still read < .1v.

Now, can someone post similar guidelines for gel-cells?  I have one that
self-discharges in about two weeks, and won't take a charging current
over 100 ma (it's a 5 ah battery) without exceeding 2.25 volts/cell.
Is it NFG?