HP Forum Archive 08

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HP 21 Rechargeable Battery Needed Message #1 Posted by Sarah Mulder on 15 July 2002, 1:04 p.m. I have been looking for a set of two rechargeable batteries for my HP21 Calculator. I have discovered that it needs two 4 volt rechargeable batteries but I am unable to find where to purchase these. If anyone knows where I can find two rechargeable batteries for my HP21 Calculator, it would be greatly appreciated. Thanks, Sarah (for Vic)

Re: HP 21 Rechargeable Battery Needed Message #2 Posted by thibaut.be on 15 July 2002, 1:39 p.m., in response to message #1 by Sarah Mulder Hello, So you have the original battery pack ? If so, it it quite easy with a cutter to open the old one and replace the original dead batteries with 2 AA rechargeable batteries. Fiding a woodstock battery pac is not only difficult, but if successful very expensive. Don't forget that woodstock calcs might fry if connected on the power supply without batteries !

Re: HP 21 Rechargeable Battery Needed Message #3 Posted by jose goncalves on 15 July 2002, 4:37 p.m., in response to message #2 by thibaut.be Two 4 V batteries ? I donīt think this is the correct value ! pls check that.

Re: HP 21 Rechargeable Battery Needed Message #4 Posted by thibaut.be on 15 July 2002, 5:03 p.m., in response to message #3 by jose goncalves Of course you're right, AA rechargeable batteries supply 1,25 V, and that's just what a woodstock need, ie 2,5 V.

Re: HP 21 Rechargeable Battery Needed Message #5 Posted by Tony Duell (UK) on 15 July 2002, 6:23 p.m., in response to message #1 by Sarah Mulder Why do you believe it needs 2 * 4V batteries? Every Woodstock (HP2x) series machine I've repaired runs off a 2.5V (or so) battery pack consisting of 2 AA-size NiCd sells in series. If you have the oriignal battery pack, you can carefully cut it open, extract the original cells and put new ones in. If you don't have the original pack, you'need to find one, etiher working, or to be rebuilt. As a general comment, _never_ throw out old HP calculator battery packs -- the plastic housing, and some of the metal contact strips are needed to rebuild the pack.

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