Path: utzoo!utgpu!water!watmath!clyde!att!rutgers!ukma!nrl-cmf!ames!pacbell!belltec!jim From: jim@belltec.UUCP (Mr. Jim's Own Logon) Newsgroups: comp.sys.ibm.pc Subject: Re: Overcharging NiCad batteries? Summary: Yup, it's really true. Keywords: NiCad rechargeable batteries, laptops, foreign power Message-ID: <278@belltec.UUCP> Date: 26 Sep 88 14:48:34 GMT References: <3008@dalcs.UUCP>Organization: Bell Technologies, Fremont, CA Lines: 26 There is method behind their madness. If you are constantly trickle charging your Ni-Cads they develop some sort of memory effect. You drain them 20% then charge them 20%, over and over again. Soon, the batteries only have 20% of their original capacity (if it used to power your portable for 10 hours, it would now only run it for 2). This has something to do with growing 'fingers' of Cadmium across the cells of the battery. By draining the battery down to nothing *occasionally* and then recharging it, the charge current helps remove these fingers. All the papers I've read on this advocate the complete discharge on a periodic basis, and not all the time. For batteries that have already become unable to hold their normal charge, there is the mad scientist solution to crush through a large current in order to vaporize the fingers. It requires a short, burst of high(er) voltage. I've tried it a few times on hurting Ni-Cads; never worked. -Jim Wall Bell Technologies Inc. The above is for someones edification, and not something that I advocate anyone to try. So if you try it, and it doesn't work; don' call your lawyer (unless he also sells batteries).