HP 41 rechargeable batteries


Can someone provide a source for rechargeable batteries for HP 82120A. I carefully opened the case, now I will attemp to replace the 4 cells.
Thank You


The original 1/2N cells are no longer made. Your best bet is to use 1/3AAA cells and some shimming since they are a different size. Try to find NiMH cells, Nicads have a rather small capacity and will not last long and tend to overcharge.


I had the same question a while ago and abandoned the idea of rebuilding my batt back. The 41C runs sufficiently long with normal batteries, so why bother...


"...abandoned the idea of rebuilding my batt back. The 41C runs sufficiently long with normal batteries, so why bother... "

Have you ever used a Magnetic Card reader or IL drive extensively?

I would certainly use NiMH batteries, if I could find them...hmmm...perhaps Lion (3V) or a camera 2-pack with 6V would be great?![nl}


Hi, all;

I just want to add the following: for those of you who own fullnuts, there is always the possibility of adding the contacts (small balls and related springs) for external power supply by using the two circular holes in the rectangular tunnel used for connecting the charger when rechargeable batteries are being used. I use the regular N-size alkalines but when I need to use magnetic cards, wand, IL or IR printer (the most power consumming "extras") I plug the external pack and go ahead.

Just a suggestion.

Luiz (Brzil)


> Have you ever used a Magnetic Card reader or IL drive extensively?

Card reader or bar code reader, no. HPIL, yes. At the last place I worked, in about 1986-87 we tested the first $2,000,000 of a product with an HP41cx controlling a rack of IEEE-488 equipment through the HPIL-to-HPIB interface converter. It was running the program 8 hours per day, making heavy use of HPIL, and a set of alkaline batteries lasted for weeks. With the way I use it now, a set of alkalines probably lasts a couple of years.

OTOH, the 41c had very little memory compared to the cv or cx, so I can understand why you'd be needing the card reader more often. I have the tape drive, and virtually never need it because everything I need fits in my 41's memory all at once, all the time.


I use GP 12AAAM NiMH cells (130mAh) to rebuild 41 battery packs. They are available at http://www.accu-profi.de/, part nr. 74010165, EUR 1.95 per cell.

For the normal battery compartement you can use GP 50NH NiMH cells (520mAh), also available at the same web site, part nr. 74010168.

Regards, Juergen


Low tech answer

You can find cordless phone packs (Uniross 84 H BC 102171- only 3 cells so you need 2 packs) quite readily with the right size (2/3 AAA size NiMh ?)rechargeables and fit these into the conventional battery holder. You need to split them up and can charge outside the calculator in an AA size charger using a nut and bolt as a spacer.

I have ordered 1/3 AAA rechargeables to rebuild the rechargeable pack but am still waiting for them after 4 weeks !


You are likely out of luck if its important to continue using the HP 82120A however a set of rechargable n-size batteries are available on eBay for about $20.00 USD. Here is the link...


I can't vouch for these but I've used similar rechargable batteries in my CV for several years.


Ha! same old story all over again. i am truly tired of disposing of of used batteries, how ever environmentally "healthy" they might be. but that's only one side of the coin. i am currently thinking of making a new rechargeable pack of my own, containing just *one* single 1.5V NiMH cell and a boost converter, let's say an ON-Semi NCP1400, or a SIPEX SP6648. This should give a real energetic advantage over the original battery pack. Question is: what is the biggest available NiMH-cell (in terms of mAh rating) that will fit into the rechargeable pack (together with the boost converter, *and* the charging circuit, of course). any suggestions??

cheers, hans


See Article 335.

I replaced with 1/3AAA NiMH cells. If I can do it, anyone can. Cells were cheap!! about $10 as i recall. there are several places online to buy.


A lot of stores that handle radio control airplanes will have the 1/3AAA cells. They are used in micro-light models.

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