Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!apple!bionet!agate!brahms.berkeley.edu!koonce From: koonce@brahms.berkeley.edu (tim koonce) Newsgroups: comp.sys.ibm.pc Subject: Re: Overcharging NiCad batteries? Summary: NiCads need to be occasionally discharged. Keywords: NiCad rechargeable batteries, laptops Message-ID: <14705@agate.BERKELEY.EDU> Date: 26 Sep 88 07:28:43 GMT References: <3008@dalcs.UUCP> Sender: usenet@agate.BERKELEY.EDU Reply-To: koonce@math.berkeley.edu (tim koonce) Distribution: na Organization: University of California, Berkeley Lines: 17 One strange fact about NiCad batteries is that if they are not sometimes _completely_ discharged, they will develop a ``memory'' which will shorten their charge life. Occasionally, they need to be discharged as completely as possible. (Best to take the batteries out and strap a 1k resistor across them for a day, but leaving the computer on until everything dies is a close substitute.) If you have a set of NiCads which run down very quickly after charging, this may be the problem. Just charge them completely, and then run them down completely several times, and they should be fine. Odd trivia: Several people I know have successfully restored ``bad'' NiCads by putting a high charging voltage (24 volts or higher across a 1.5 volt cell) on them for a short while. This seems to burn out small bridges that form internally after a while. - Tim Koonce