Newsgroups: comp.sys.laptops Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!psuvax1!sol4!cho From: cho@sol4.cs.psu.edu (Sehyeong Cho) Subject: Re: Batteries Message-ID: Sender: news@cs.psu.edu (Usenet) Nntp-Posting-Host: sol4.cs.psu.edu Organization: Penn State Computer Science References: <46Gdxpf1@cs.psu.edu> Distribution: usa Date: Wed, 3 Apr 91 03:44:34 GMT Lines: 30 In article <46Gdxpf1@cs.psu.edu> I wrote: >I decided to follow the advice: "discharge the Nicad completely before recharge" >I made a simple device that has two contact points and a light bulb for >a car. Can a discharge be "too fast" or "too slow" so it can cause a problem? >For instance, can I just short-circuit the +/- ? (Okay, assuming fire won't >break out :-) Someone replied: |The NiCad is made up of several cells in series, so you do NOT want to |completely discharge them, as you may reverse charge some of them, which is bad |news. Complete discharge only works for single cells (1.2V), and you should |add limiting resistor, as short circuiting NiCads is not good for its health. The advice I got from this news group was: If you charge a partially discharged Nicad battery, you may end up ruining the battery by what is called "memory" effect. Therefore you should completely discharge the battery before recharge it. Now I have two (apparently) contradicting theories. The only way to be consistent is perhaps "before you begin recharging the battery, make sure it doesn't have too much charge remained." But then how much is too much? Any idea? -- | Yesterday I was a student. Sehyeong Cho | Today I am a student. cho@cs.psu.edu | Tomorrow I'll probably still be a student. | Sigh.. There's so little hope for advancement.