Re: Rechargeable Battery for HP-29c


You have to rebuild these yourself. Cut the thin bar between the batteries and replace with NiCad rechargables. Some people have used other types (alkaline NMH) but I am not sure they can be recharged in the calc (of course the alkaline cannot)


Nickle metal hydride cells work great in the Woodstock machines. But, if at all possible, NEVER charge a pack in your 29C or 25C. These machines are very fragile electrically. If your pack is not making good contact or has an open cell, voltages large enough to damage the machine are produced... EVEN IF THE MACHINE IS TURNED OFF!. The other Woodstock machines are a LITTLE more forgiving. At least when the power switch is off, the electronics are truly turned off.

Try to find the external charger stand (hard to find) or a beat up or dead machine (all too easy) to use as an external charger.

Any good battery store (Batteries Plus, Batteries, Etc) can rebuild your old pack for less than 20 bucks. In a pinch you can put a couple of AA alkaline cells in the holder. Just dont connect it them to a charger.

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