Please Help with Battery for HP 28C


Is there anyone that can help me with information about the type of battery that can/should be used in a HP 28C, also where I can buy them. I lost my manual and I had stored the calculator without battery. Thank you John




They are available at Office Max, Office Depot, Walmart, KMart. Just have to look for them. They are N size batteries. Duracell Part No is MN9100


I prefer Eveready Energizer or Duracell brand batteries over Radio Shack for one simple reason. The Eveready Energizer and Duracell batteries are guaranteed by the battery manufacturer not to leak (even if you forget to use the calculator for yaers and leave the battery in it). I have used Radio Shack in a pinch.

In 1984, six weeks after installing newly purchased Eveready N-cells, the batteries dis=d leak and corrode my HP-41CV. I mailed it to Eveready, who sent it to HP to fix it. A month later I had it back, good as new. Today I am afraid Eveready or Duracell would have to pay you cash, as HP does not service the HP-41.


My first HP was a 41CV that was given to me around 1986~87 by a mechanical engineer at the automation company where we both worked. It had been issued to him in the military, and when he completed service, he had left the 41 in a drawer (heaven forbid!) for what must have been a couple years. When I mentioned I was going to buy an HP, he said I could have his 41 because the batteries leaked and it didn't work anymore.

I sent the 41 to HP (with the batteries still in it) for repair. A couple days later I received a letter from HP stating the repair would cost $90 and that I needed to sign the authorization line and mail them $90 before work could begin. I waited a couple days debating whether I wanted to spend $90 and end up with a still used but repaired calculator (the letter didn't say an HP "repair" actually meant "replace with new".. remember, it was my first dealings with HP).

A day or two later, a box arrived at my house with a brand new 41CV and another letter from HP indicating that since I didn't cause the damage, but rather the leaking batteries did, they simply sent me the new calculator and sent the $90 repair bill to the battery manufacturer (Eveready or Duracell, can't remember which).

Needless to say, I was absolutely sold on HP quality and customer service. I now have 40+ HP's.

Oh yeah, I did give my mechanical engineer friend $50 as a peace offering, since I was often found proudly gloating over my new --free-- HP.



The cheapest (common) place that I have found "N" cells is, strangely enough, Home Depot.


Radio Shack is your best source for weird batteries. Especially N cells, and NiCds used for rebuilding packs.

I tell the guys there that I'm getting batteries for my calculator collection, and they look at me strangely. After I tell them I have about 50 HP calculators, they just shake their heads.

Anybody else get this type of response?



Yes, but he was about 16 and clueless. He told be Radioshack offered plenty of great new calculators that could do anything I needed. lol.


Yes, and it's always funny when you go into a store to see what HP calculators they might have and they try to ask what you want to do with it so they can try to sell you what they have. I give them an "A" for effort, though. It's refreshing to see people intersted in doing their jobs!


We have an Interstate Batteries store nearby that I've been to several times. Once I asked whether N cells were used in anything other than HP calculators. I was told they are used in some kind of security or tracking or something equipment in the trucking industry. Are they also used in the GameBoy?


Game Boy uses regular AA batteries. Could you imagine if parents had to find N size batteries for their kid's toys? They would be pulling their hair out!


I don't know if they are used for cameras or for accesories like flashes, but I usually get my N cells from photography shops.


someone here said n cells were used in the first pokemon things (games or toys?). so i guess there are a lot of pelon parrents after all.


N-size cells are used in some LED-lamps for bicycles.

Regards, Bo


N cells must be used for some fairly common items. My local Albertson's grocery store has them.


My first encounter with an "N" cell was with an "N" scale model railroad! It was used in a boxcar to run a flashing LED on the back end of the boxcar to simulate the
Freight Rear End Device (FRED-that little box that
replaced the caboose on a freight train).
Our local Batteries Plus has them in stock, but I believe
they don't call them "N" cells, but by some stock #.
And make sure they don't sell you the similar sized 12volt battery by mistake!


Hello all:

I'm only dipping in here...I've been too busy with real-world junk lately to keep on the MoHPC Forum! :-(

BUT, I did want to let people know that a good (but a bit unusual) source for batteries is:

These guys stock lots of different types, and some of their prices are outstanding (check out the silver-oxide 357 batteries for the 10-series calculators). They carry N-cell, and many others. They _do_ charge an extra $5 fee if your order is under $50, though, so stock-up and use the freezer!

Oh, one more suggestion. They carry lithium 9-V batteries. These are GREAT for smoke detectors, as you can put them in and forget about them for about 5 years!


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