Re: [NTLK] Battery Oddities...

From: Thomas Hofts (
Date: Wed Jun 26 2002 - 14:40:41 EDT

on 6/26/02 1:17 PM, John Goggan at wrote:

> Sorry for bringing this back up -- I know others have asked and possibly
> answered, but I never quite "got it." I've got several batteries that all do
> the same thing... They seem to last only an hour or two -- and, when
> charging, they go from 20% to 100% within minutes (or even seconds
> sometimes). In other words, they obviously aren't really charging...
> I recently installed BattTrax to try to get a better idea of what is going
> on. When I started charging, capacity was at 19%, battery temp was about at
> 27C, and my current was right around 1020mA. It charged normally for about 2
> minutes -- during which time the capacity rose to 21% and the battery temp to
> 27.5C while current stayed relatively stable.
> Then, suddenly, capacity jumped to 100%. The graph in BattTrax ust goes from
> 21% to 100% in one 2-second interval. Battery temperature, at that 2-second
> interval, dropped to 27C again, and charge current to 0.
> It then just stays there doing trickleChargeContinuous at 0-1mA only.
> Forever.
> Is this a situation where I should start trying fridge/freezer tricks? Is
> this a battery temperature issue? Or batteries that just aren't going to
> recover?
> Any suggestions appreciated. All 3 of my nimh packs seem to be giving the
> exact same behavior (on different Newtons, just to note that I don't think it
> is specific to a Newt).
> Thanks!
> - John...
While there may be no sound scientific reasoning, I'm a firm believer in the
"freezer reconditioning"

If you get the NiMh pack too cold (below 40 f) it may only trickle charge
until the battery temp. hits 50-55 f.

I noted the displayed capacity increases proportionately with the battery
temperature. By placing a small cloth wrapped salt and ice pack on the
battery end of the Newt and keeping the battery temp to about 65f, it will
show it taking a "fast charge" for about 20 minutes after it "shows" 100%
capacity or until the battery temp exceeds the ambient temp.

I got a total charge time of 1:20 and a good week of occasional daily use
with backlight. When I got the Newton it took 10 min to charge and only
lasted a day.

Tom Hofts

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