HP-11C - Amazing Battery Life


Today (7/6/2010) I removed the *original* batteries from my 1986 HP-11C and wrapped it up for permanent storage in my collection. I used the calculator infrequently over the years, but it was always nearby for a quick calculation. Believe it or not, the batteries still powered it enough for usage today. I am amazed! 24 years on the original set of batteries! Wow!!!

(The image is from *this* site and is not my calc.)

Edited: 6 July 2010, 8:16 a.m.


Dear Bill:

What a beauty.

I know this has been beaten to death already, but here is another plea to HP to bring back a horizontal-format scientific of traditional construction and layout.

I recently bought a "gold", garden-variety HP.12C (no "Platinum" or "Anniversary" gingerbread) and am pleased to say that, at least in feel, it approaches the 1980's original.

We'll see how it holds up - I may not be around in 24 years to check the batteries :).

In any case, HP CAN produce a stout, well built horizontal format machine, and with use of modern central processor and ROM system program it any way they want.

New faceplate and keys and you have ---->>>> HP.11/15C II ++

Last, but not least, some of you microcode experts may be able to "reprogram" the 12.C through its plug and provide a keyboard overlay for an "Ersatz-15" or such.

John Stark


...here is another plea to HP to bring back a horizontal-format scientific of traditional construction and layout.

There is no such thing as a traditional landscape (or as you term it...horizontal-format) HP calculator. Everything before and after the unfortunate landscape Voyagers has been in the much more practical portrait format...for very good reason: The landscape format is terrible for those who ever actually use a handheld calculator as (imagine this!) a handheld calculator. HP has done a number of stupid things in the years since the HP-35 appeared...but they've never been stupid enough to re-introduce the Voyager format except for those interminable HP-12C variants that appeal to business major types.


Financial guys have big mahogany desks. Well, maybe not as big as the lawyer's, but big enough.


As one of those who have actually used the 15C as a hand held, I must disagree with your assessment of its utility. It is my favorite calculator, precisely because it worked so well as a shirt-pocketable and hand held device in my earlier days, mostly spent on my feet in a lab and field environment. The HP-25 and and 41 rarely left my desk.


There is nothing natural about using a Voyager as a **handheld** calculator unless one has a very bizarre palm and finger-length arrangement. Those who like that layout usually will ultimately admit that its real appeal is that it is sooo "cutesy". I still have two HP-15C units and one HP-12C unit that I've used for more than 25 years, and IMHO their landscape arrangement is idiotic in the extreme. The portrait Pioneer HP42S greatly exceeded and improved the capabilities of the HP-15C in every aspect. Unfortunately, the HP42S is 1988 technology, and HP hasn't the technical talent to produce something with the capability and size of the 22-year-old HP42S. Instead, abominations like the HP32SII, HP33S, and HP35S characterize the best that HP has been able to muster the past two decades. However, I fully admit that for a rather large calculator, the HP50G is a damned fine machine, one that is much better than TI competition. I wonder who HP got to design it.


Maybe just a problem of mine: I rarely have enough 'vertical' space left on the desk to place a portait calculator, but my TI-66 fits nicely underneath (would 'below' be the better word to use?) my keyboard. I agree, it certainly is not made to fit the palm, but I prefer using the calculator on a more stable surface anyway.

I don't want to buy another new HP calculator due to all the problems they have. OTOH, a reintroduced 15C could make me think twice.

Edited: 8 July 2010, 12:02 a.m.


Yes John, it is quite a beauty! :)


what brand of battery are they?

i removed a set of union carbide cells a few years ago that had served 15 or 16 years.


I don't know what the brand is - but as I had written they were originally packaged with the calculator.


Probably they are silver-oxide (SR44), which are supposed to last twice as their cheaper alkaline equivalents (LR44)... However, more than 20 years is amazing, indeed!


My Wife's Sharp Elsimate from around the same time is still on its original AAA battery.


It is amazing how little "juice" these machines need to function. :)

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