From: Chris Holt <amiga2k_at_cox.net>
Date: Mon, 30 Jun 2003 20:00:29 -0400

On Mon, 30 Jun 2003 18:05:28 +0200, Joris van den Heuvel wrote:

> Could you please explain why this is so? As far as I know, this is only
> true for lead acid batteries and in a lesser degree Li-ions. I have
> drained MANY NiCd and NiMH cells to nearly zero, and have never noticed
> a decrease in performance.
>
> I do know that you shouldn't load NiMHs with large output currents >1C,
> as you could NiCds.

Without doing a lot of research, I cannot explain why this is so. I can
confidently state that I have seen this recommendation on every reliable
source of info on the care of NiMh batteries. Reference:

http://www.rccaraction.com/rc/articles/NiMHbatcare1.asp#Q8
http://www.advanced-battery.com/BATTGUID.HTM

All in all, it is the general recommendation. I believe that NiMh cells
are tolerant of over-discharge, but with the majority of electronic
devices providing a "built-in" discharge cutoff of 1v/cell or close
enough, I don't really see the need to go out of my way to do an external
discharge, full or otherwise. Simply run the device till it shuts down.
(with obvious exceptions like PalmOS PDAs that lack button cell backed
RAM)

For a fairly complete descripton of the chemistry and construction of NiMh
cells see: http://tinyurl.com/foop (PDF file)

Chris
Received on 2003-07-01