[TriLUG] Linux laptop battery

al johson alfjon at mindspring.com
Thu Feb 7 02:36:32 EST 2002


It's very easy to see with single cells such as AA nicads. Put a volt meter
on them and the positive terminal will be negative and the negative will be
positive. This is harder to see in a larger battery such as those used in
laptops, because there are many different cells wired together into one
large battery. But if you reverse just one of these cells the battery will
never work properly again. Cell reversal can also be caused by overcharging
a battery.

----- Original Message -----
From: Vestal, Roy L. <rvestal at rti.org>
To: <trilug at trilug.org>
Sent: Wednesday, February 06, 2002 8:02 AM
Subject: RE: [TriLUG] Linux laptop battery


> Depending on your MFG, this may or may not be true. For the Ni-Cad and
NI-MH
> batteries in toshibas, for example, have a small circuit built in to
protect
> from any kind of polarity reversal. I believe Thinkpads do as well.
>
> -----Original Message-----
> From: Chris Merrill [mailto:cmerrill at nc.rr.com]
> Sent: Wednesday, February 06, 2002 7:53 AM
> To: trilug at trilug.org
> Subject: Re: [TriLUG] Linux laptop battery
>
>
> al johson wrote:
>
> > You should also NEVER run Ni-cad or NI-MH batteries until they are dead
> > either!! If you do, you will risk reversing the polarity of one of the
> cells
> > and the battery will never recharge properly again. (a battery is
composed
>
>
> Either this is not true, or the chance of it happening is very,
> very small.  I have always fully drained my NiCad batteries after
> use prior to storage or charging.  A few particular sets (used in
> a walkman during college) went through literally _hundreds_ of
> cycles - most of which had a _full_ discharge: which (for me)
> meant discharge to the point where they would not even warm
> the filament of a 3W light bulb.  I have NiCads that have been
> used in this manner for >10 years - and they work fine.
>
> I have never heard of 'reversing the polarity' of a dry cell,
> or any other battery, for that matter.  From what little I
> remember from chemistry 101 it is not chemically possible in
> wet cells.  I am very interested in this 'reversing polarity'
> concept - Do you have some sources of information on this?
>
> I'd also like to see the NASA research paper...since I have
> seen research to the contrary (I wish I had a copy...).
>
> *********************************
> Chris Merrill
> cmerrill at nc.rr.com
> *********************************
>
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