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HP Forum Archive 14

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Rechargeable Battery Packs
Message #1 Posted by George on 1 Mar 2004, 7:09 p.m.

I have read through the "Battery Packs & Chargers" section but did not see the newer NIMH batteries addressed. When building a pack can I use the higher mAh NIMH batteries? If so, can the charger for NiCads be used to charge the NiMH batteries?

      
Re: Rechargeable Battery Packs
Message #2 Posted by David Smith on 2 Mar 2004, 1:16 p.m.,
in response to message #1 by George

Yes, you can use NiMGH cells just fine as long as the recharger is a slow charger. I have been doing it for years. My HP67 runs up to 12 hours on a charge. Just rememeber to multiply the charge time by the increased cell capacity percentage to get a full charge. You do not have to worry about fully charging or discharging NiMH cells like you do with Nicads.

            
Re: Rechargeable Battery Packs
Message #3 Posted by Giuseppe Marullo on 3 Mar 2004, 1:37 p.m.,
in response to message #2 by David Smith

I have the same problem, the replacement available are NiHM, either in "N size" or 1/2 "N size".

I don't think they are the same, the trickle charge may cause problems if you overcharge them, I would like to be on the safe side when I will recharge them into a 41CX.

I was hoping someone already faced the problem, but a previous post went unanswered.

                  
Re: Rechargeable Battery Packs
Message #4 Posted by George on 3 Mar 2004, 7:19 p.m.,
in response to message #3 by Giuseppe Marullo

I was hoping to apply any information learned here to also build a 12 volt battery pack for my surveying instrument. It too has a NiCad charger. I have already purchased off Ebay 10 "C" size NiMH rechargeables to replace the Nicads. When they arrive I'll try it and if it works I'll let you know.

                        
Re: Rechargeable Battery Packs
Message #5 Posted by Giuseppe Marullo on 5 Mar 2004, 10:18 a.m.,
in response to message #4 by George

George,

http://groups.google.com/groups?q=%22charging+nimh%22+trouble&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=39AC48CC.83CF764F%40mediaone.net&rnum=4

http://groups.google.com/groups?q=%22charging+nimh%22+trouble&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=x7lnrgx8c2.fsf%40capsicum.wsrcc.com&rnum=6

I hope that the low charge current will make no difference between NiCd and NiMH, just wanted someone already jumped on the wagon to tell...

                        
Re: Rechargeable Battery Packs
Message #6 Posted by David Smith on 5 Mar 2004, 12:44 p.m.,
in response to message #4 by George

Oddly enough AA MiNH cells are the most efficent power vs volume and price wise. You can get 2000maH in a AA package (don't beleive those 2300maH claims). Sub-C cells commonly go to around 3200 maH. Most of the "C" and "D" NiMH cells are big packages with small, low capacity cells inside of them.

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