Re: [NTLK] 2100 battery recharge questions

From: speedy2 (speedy2_at_dag.net)
Date: Fri Apr 05 2002 - 11:12:31 EST


On Fri, 5 Apr 2002, John Goggan wrote:

> Now, NiMH batteries (and other types of rechargables) do have a fairly
> constant, but slight, capacity loss over the lifetime of the battery.
> More recent NiMH batteries will lose 10-15% of their capacity over their
> lifetime. For older NiMH, I am told it was even more -- so what the
> Newton may have, I do not know.

NiCd memory effect is not a problem these days and is grossly
over-exaggerated. NiMH's while having a higher density, also have a higher
self-discharge rate (compared to NiCd). This means a NiMH not being used
actively will lose power on it's own.

A lot of people see the memory effect on NiCds or NiMHs because they
decide to discharge a pack before re-charging to eliminate the "problem".
Unfortunately many people discharge a pack to the point where one or more
cells go into "reversal" and cause a more significant problem.

Reversal occurs because one or more batteries do not have the same voltage
on them and discharging cells in a pack below a certain point allows one
cell in the pack to "charge" another cell in the pack in the wrong way
(i.e. the charge polarity has been flipped). Battery packs where cell
reversal occurs irreparably damages the cells and at the very least
shortens the life time of the cells.

All the being said, NiMH cells are more environmentally friendly compared
to NiCd, and when used properly (i.e. with a good battery charger) will
yield excellent results. The key is to use a good batter charger which I
think the Newton has...

Thanks,
Speedy2.

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