Re: [NTLK] Constantly charging NiMH batteries from BTI

From: Kim Howe (khowe_at_omninet.net.au)
Date: Thu Aug 30 2001 - 01:42:41 EDT


On Wednesday, August 29, 2001, at 09:09 PM, Laurent Daudelin wrote:

>
> on 29/08/01 02:53, Lallang_at_aol.com at Lallang_at_aol.com wrote:
>
>> When I'm not using my Newton 2100s, I have it plugged into the power
>> adapter
>> which charges the NiMH battery I got from Battery Technology so that I
>> can
>> always have the 2100s at full charge when I am out in the field. Is
>> this a
>> bad thing where the battery is concerned? I had thought it not to be a
>> problem since NiMH batteries are supposed to be free of the
>> hysteresis/memory
>> effect that plagues NiCd batteries? Thanks.
>
> Last I've read on the subject (Frank, you correct me if I'm wrong ;-) is
> that they don't have memory effect *as bad* as the NiCADs, but they can
> develop some more or less serious memory effect if you always recharge
> them
> before they're drain out. If you completely drain them every once in a
> while, they would probably keep their charge longer.

I have had some experience of this in my UMP2000. If I plug my Newton
into power each day and download news to Inkspot (so that it gets
charged after only a little discharge) the life of the battery between
charges will decline so far that it will be flat after 1-2days of normal
use. If I then cycle the batteries to flat a couple of times, the normal
pattern returns where I charge about once a week. I'm pretty pleased
with the battery pack, it's still the original one that came with the
2000 when I got it. People quote battery life in cycles, but I've found
they will often last way beyond the number of cycles. (I once cycled a
set of 10 500mA/h Nicads 1200 times without a failure in any of the
cells, but they were cycled daily over a 3 year period.)

So to answer the original question. You can leave your batteries on
charge for a while, but you will want to cycle them every so often. Are
you in a position where you find yourself unable to access a charger for
several days at a time? If not, you could just use the Newton and charge
when the batteries are running low. I find that I still get a few hours
use even after the battery is down to 20%.

Hope this helps

Kim Howe
Newton Forum Host on Syndicomm.
kimhowe_at_syndicomm.com

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