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From: phil@diablo.amd.com
Newsgroups: sci.electronics
Subject: fast chargers
Message-ID: <28472@amdcad.AMD.COM>
Date: 19 Dec 89 19:42:40 GMT
Sender: news@amdcad.AMD.COM
Reply-To: phil@diablo.amd.com ()
Organization: Advanced Micro Devices, Inc. Sunnyvale CA
Lines: 24


There's an article on fast chargers in EDN, 12/7/89.

It has a nice graph of three parameters, voltage, temperature, and
pressure as the battery approaches overcharge. It looks like
temperature is a useful charge indication and that pressure starts to
climb at the 80% level. This is important because if the battery isn't
made to handle the pressure between 80 and 100%, it will vent and lose
electrolyte. 

But the best indication is negative delta voltage. NiCds will drop in
voltage right when they reach 100%. They show a simple looking circuit
but caution that it really isn't that simple. 

Lead-acids seem more difficult and variable and no general solution
for fast charging is offered, but they do say the most common charging
(as opposed to fast charge) is constant-voltage. 

Finally, they have an express request system for info from the
manufacturers. It sounds great!

--
Phil Ngai, phil@diablo.amd.com		{uunet,decwrl,ucbvax}!amdcad!phil
Ann Landers says "Let's talk about legalizing drugs."