HP-41C rechargeable batteries

Everything about 41C 41CV and 41CX Hardware

Re: HP-41C rechargeable batteries

Postby scan80269 » Mon Jul 08, 2013 3:03 pm

This is my first post.

I have found a source for N-size 500mAH NiMH rechargeable batteries for the HP-41 in the U.S.:

http://ogazent.com/cscart/index.php?dis ... egory_id=5

They also have N to AA battery adapters to allow the N-cells to be recharged with a AA NiMH battery charger. I use a MAHA MH-C9000 charger which has an option to set the charging current down to the 50mA setting needed for these batteries. This charger was bought from http://www.thomasdistributing.com

These rechargeable N-size NiMH batteries are far more economical to use with HP-41 than disposable N-size alkaline cells.
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Re: HP-41C rechargeable batteries

Postby StickyFox » Sat Aug 23, 2014 11:27 pm

Thanks sm5hua for the link to the batteries ... I was having a hard time finding anything suitable! I did see rechargeables on ebay for £55 a pair ... :shock:

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Re: HP-41C rechargeable batteries

Postby Garth » Sun Aug 24, 2014 2:08 am

I'm not quick to recommend rechargeable batteries for the 41 unless you're using the card reader or the bar-code reader wand a lot. My own 41cx went two years on each set of alkalines even with everyday use, until I got a double extended memory module which seems to have more leakage current and took the battery life down to around six months on a set of alkalines, again with everyday use. If you use rechargeables, you'll have to have two sets if you have to remove one set to put it in the charger, using the second set to preserve the memory while the other set is getting charged. The price of two sets of rechargeables plus charger will buy many, many years' worth of alkalines, and the rechargeables need more-frequent attention because of their self-discharge rate. Yet another point is that if the rechargeables are 1.2V, my own 41 would show the low-battery annunciator all the time, because it comes on at 1.2V. Again, I don't recommend rechargeables unless you often use the card reader or the bar-code wand. I have the tape drive, but I have enough memory in my 41 to perpetually keep everything I need in it, so I virtually never have to access any kind of external storage.
http://WilsonMinesCo.com (60 HP-41 links on the links page)
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Re: HP-41C rechargeable batteries

Postby StickyFox » Sun Aug 24, 2014 10:23 am

Garth,
Excellent advice .. I only recently found out you could get such a thing as a N cell chassis. So I assume no-one really bothers with the original HP chargers, either then. This is all great news, looks like with an alkaline battery chassis, you can carry on for years at negligible cost. I was freaking out because I couldn't replace the native rechargeables!
What's a sensible inspection period to check for leakage? 6 months?
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Re: HP-41C rechargeable batteries

Postby Garth » Sun Aug 24, 2014 3:12 pm

StickyFox wrote:What's a sensible inspection period to check for leakage? 6 months?

Since mine turns on the low-battery indicator at 1.2V which really isn't very low (like a 9V battery being down to 7.2V), there seems to be no danger of leakage at all if I replace the batteries when it comes on. I'm sure I could continue to use them for a long time after it comes on, but then I would have to check frequently for voltage (to make sure I don't lose anything in memory) and for leakage. I have never seen any leakage. I've been using my 41cx every day for 28 years.
http://WilsonMinesCo.com (60 HP-41 links on the links page)
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Re: HP-41C rechargeable batteries

Postby StickyFox » Sun Aug 24, 2014 10:04 pm

Sorted - thanks! Every day, huh? 10 to the four days. That's a lot of RPN.
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