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Full Version: Creating NiCD pack for HP-41
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as I've got several HP-41s, which I activate only from time to time, maintaining battery power is either a hassle. Either I switch calcs with only one complete pack or I have to buy quite a lot of these expensive N cells.
I wasn't yet lucky (or willing) enough to get a NiCD rechargeable pack.

Has anybody come around DIY instructions how build a NiCD pack from a normal battery holder? The only things I've seen so far were REbuild instructions, but, as it says: rebuilding is not possible without the building :-)

N sized cells are not too hard to find, it's the connection to the charger, that troubles me.

Thanks for any help.

Easy, just buy four nicad "N" cells and an external charger. If you need to keep the machine alive while they charge buy eight.

I found, that as long as you don't press any keys, especially the ON key, the HP-41 will hold its memory for at least a day or longer without batteries. This is for a unit that is used daily though not one that is in storage and is powered up on occasions to keep the circuits alive.

I agree with David. In North America Radio Shack caries those (part no: 23-521), they are ~$9 for two NiMH N batteries (in Canadian dollars). As for the charger I use the regular Energizer (or Duracell) with battery charging module for N cells. That is just a spacer to convert N size into AA size, also sold at Radio Shack for $2 for 4 pieces (part no: 23-137).


Edited: 2 June 2004, 3:35 p.m.

Most HP41C machines can hold up for several days without batteries. CV's at least a week. I have CX machines that lasted over a month.