N batteries for HP 41's


Tuesday, January 10, 2012
Until today, I was buying N batteries for my HP 41CX at my local Radio Shack. They were costing $6.39 + tax for 2. Today I stopped at my local Staples store, and discovered they handle the N batteries, but the cost is only $3.29 + tax for 2. The Wal-Mart stores I've checked do not carry the N battery anymore. If anyone knows of any other sources for N batteries, please add to this thread for future reference. Thanks


At Digi-Key: http://search.digikey.com/us/en/products/E90VP/N147-ND/704824 85 cents each for Energizer alkaline if you buy 10.

At Mouser: http://www.mouser.com/ProductDetail/Energizer/E90/?qs=sGAEpiMZZMvWbzBWipm%252bdcEu2SKy6Jl5mvewqmREHRQ%3d $1.34 each for Energizer alkaline if you buy 10.


Many supermarket pharmacies also carry N-type batteries.


I bought 4 N, rechargeable, with a charger on eBay for less that 2 Duracell from Radio Shack...


I got my last N batteries at Radio Shack.


I've seen them at Rite-Aid as I recall.

Radio Shack is way expensive...would hate to have them as my only source.


For UK readers:

I just bought 20 from here:
£10.70 and free delivery.



So ... to extend the life of all the other batteries one might purchase in order to get a better price, should they be stored at a temperature below freezing, just above freezing, or room temperature?


Duracell says: "We recommend storing batteries at room temperature in a dry environment. Extreme heat or cold reduces battery performance. You'll want to avoid putting battery-powered devices in very warm places. In addition, refrigeration is not necessary or recommended."

Kodak says: "We recommend storing batteries at room temperature in a dry environment. Extreme heat or cold reduces battery performance. You'll want to avoid putting battery-powered devices in very warm places. In addition, refrigeration is not necessary or recommended."

Elsewhere I saw suggestions that it not be too dry (can suck the moisture from the battery chemicals).

So, it looks like you don't have to do much but keep them in the house where it's not too cold and not too hot. (Check with Goldilocks!)


I used to have a job that took me to an extreme cold environment. We had to keep batteries close to our bodies when not in use. Otherwise they quickly become cold soaked and useless.


I have bought from this seller two packs of 12 N size batteries. Free shipping.


I only use recharge batteries. It's nice and cheaper... Regards...


That's not always an option. My 41cx halfnut would show low battery even on a fresh charge, because the voltage on rechargeables is not enough. Why use rechargeables and have to keep recharging though when a set of alkalines lasts a couple of years without having to think about it, unless you're using the card reader or the bar code reader a lot.

Edited: 13 Jan 2012, 2:49 a.m. after one or more responses were posted


You have to buy new rechargeables then... mine (I have several of them) do not show the low battery warning, when fully charged, on any of my 41s.
You will like them when you have peripherals, not limited to the card reader anymore, that eat quite a lot of juice. :)



When the battery voltage is down to 1.20 to 1.25 volts, ie, the voltage of rechargeables, my BATT annunciator goes on. But even back when I was interfacing to lots of equipment on HPIL, the alkaline batteries lasted a very long time.


On my 41C and 41CV the BAT announciator comes on as soon as the voltage of the battery pack has dropped to quite exactly 4 V, which means 1 Volt per cell - the usual final discharge voltage of a completely empty NiCd/NiMH battery.

So if your 41CX turns on the announciator at 1,25 V per cell there's something wrong - in this case it would almost permanently display BAT when HP's own NiCd-pack 82120A is used. Which of course is not the way the announciator is supposed to work. ;-)

That's why I think there's a problem with at least one of your rechargeable batteries. One of the cells seems to be dead, or at least its voltage drops more rapidly than in the others. You may determine the voltage of each battery separately with a load of, say, 50...100 mA. Metering the open circuit voltage of the complete pack does not make much sense here.



I've never used recheargeables with it, but I always measure the voltage on the alkalines when the BATT annunciator comes on, and the four of them together produce close to 5V. I realize the voltage will be lower under load, but the load when the calc is on but idling is only a couple of mA, and other extensive battery-life testing for our products tells me there's still a fair amount of energy left there. However, since the 41 is so valuable and I don't want to ever have any leakage, I replace them immediately when the annunciator comes on.


I have never bought any alkalines for my HP-41s. Back in 1981 when I got my first HP-41, I replaced the supplied alkalines with a 82120A (which was pricy) once the original batteries drained after a couple of months. I usually charged it once per week for years and I used my HP-41 a lot back then.

When the 82120A finally died, I switched to to NiCd N cells and some 5+ years back NiMH N cells (which now need to be replaced).

Rechargeables have work fine for me for years, not a single problem.

I also use NiMH cells in my 48GX, but that one give very short notice before it lose memory after the low bat indication comes up...

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