[NTLK] MessagePad 2100 recell problem
gavin83209 at gmail.com
Sat Aug 7 22:13:56 EDT 2010
On Aug 6, 2010, at 3:14 AM, Forrest Buffenmyer wrote:
> First off--have you read Frank Gruendel's excellent article on
> recelling the Newton Ni-Cad battery pack? It can be found here: http://www.pda-soft.de/mp2k_battery_pack.html
I have read that, actually. Good stuff.
> 1. I buy my batteries here in the US at a store called Fry's
> Electronics. They're big in California, but there's also stores in
> Arizona and Texas, and I'm sure several other states. They're
> primarily in the Western US...they have a website called, oddly
> enough, www.frys.com. They're certainly not the only source by
> far...but I can walk in there and walk out with what I want, after
> looking at about a dozen different offerings by several companies,
> most well known (avoid the Vivitar batteries, though!).
Fry's is a good store. I have one a bit under an hour away from where
I live, though I mostly buy specialized batteries like this online in
bulk, if possible. These particular batteries are actually from
Walmart, though. I've rebuilt a few battery packs for other devices
in the past and I'm impatient with shipping, so I just got some
precharged Rayovacs without tabs, as I said previously.
> You should be getting something in the 2000-2600 mA range. In most
> cases cost doesn't play a big part in which you choose within that
> range...Eveready, Sony, Ray-O-Vac are all good proven choices, and
> run from about $12 USD to more than $20 USD.
Mine are rated at 2100 mAh for $9.97. I used the same things in my
MessagePad 110 a while ago with success.
> 4. The thermistor is VERY important, and I would bet that's part of--
> if not all--of your trouble. If it's not possible to salvage the one
> you had originally, you'll have to find another pack and cannibalize
> its thermistor. ALSO VERY IMPORTANT is the small strap with the
> yellow sticker and numbers on the bottom of the pack that connects
> the negative and positive ends of the two cell "pairs". It's been my
> experience that without it the pack just won't function properly. I
> *can* tell you that you don't need a lot of material left of the
> original piece there to have it work okay..but it does have to be
Well, I am somewhat embarrassed to say that I misidentified the
thermistor in my previous email. By thermistor, I meant the little
yellow square. It has been reattached with a few strands of what used
to be twisted copper wire and electrical tape as a temporary measure,
but it still doesn't seem to be working quite right. I also seem to
have somehow misinterpreted a bit of the wiring in the process. The
thermistor seems to output voltage at least. I don't currently have
access to a working multimeter (mine seems to be dying), but I should
tomorrow. I'll test it then.
> 5. Frank says that you should test the pack when completed by first
> checking DC voltage from the silver contact disk (negative) to the
> right side contact (positive)...it should be 5-6 volts (assuming the
> cells were pre-charged--almost all are). Check how well the
> thermistor works with the two contacts on the obverse side --10
> kiloOhms is good, but the temperature can cause this to vary widely.
> Any other wider variance in any of these numbers and there's
> something wrong/not connected properly.
The wiring all looks fine to me, though it hasn't been properly
tested. I reattached the positive thermistor contact on the logic
board again (it's not going anywhere this time!), but it still doesn't
appear to work. I'll keep these voltages in mind when I run a proper
> I hope this is a help or at least a step in the right direction.
Very much so. Thank you sincerely. It has been an enormous help.
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