Zapping Laptop batteries

From: Lawrence Walker <lgwalker_at_mts.net>
Date: Fri Nov 15 21:00:18 2002

 I'm lucky enough to have picked up an old marine battery charger for $5 at a
yard sale last year. It's good for 6v-60v. with voltage and amperage controls
as well as a 10A limiter switch. As I say, I've got about a dozen Ni-Cads and
about a dozen laptops, none of which, except an old NEC, which has a
working battery. Also a Commodore 386 that I've been unable to find a power
supply for,( has a strange 5pin mini-din plug, made by Sanyo I believe
also labelled as a Zeus, and Everex). I have to decide which laps I want to
use as carry-abouts and possibly rebuild them myself as even the rebuilders
charge about US$60 ($6000 Canadian ? :^} ) And if I have to take them apart
anyways I may as well get my own replacement cells and use duct-tape.

 Thanks all. There's also a PD program called "deepdran.exe" (deepdrain)
which I can use to exercise the batteries after, if it's successfull. Worth a try.

Lawrence

> > >
> > >What really happens is that minute 'hairs' grow from terminal to
> > >terminal in the cell, effectively shorting it out. To remove them
> > >requires a flash of current to 'burn' them out. Either a high current
> > >source (10A or more) or a large capacitor discharged into the cell does
> > >the job.
> >
> > I have used an automobile battery to "zap" them. Shorting a NiCad
>
> Rather you than me! A car battery can provide a rediculously high current
> (at least 500A), and the risk of the NiCd exploding is pretty high as a
> result. I prefer to use a current limited bench PSU (10A max), and even
> then to just 'tap' the contact.
>
> > to an auto battery for just a split second usually burns out the
> > whiskers. HOEVER the fix usually doesn't last long. One of things that
>
> Agreed. As you seid below, the NiCds will work long enough to prove that
> the rest of the device is working and that it's worth investing in a new
> set of NiCd cells.
>
> -tony
>


lgwalker_at_mts.net
bigwalk_ca_at_yahoo.com
Received on Fri Nov 15 2002 - 21:00:18 GMT