What battery for 11 C?


I'm remembering 675, but the batteries that came out are energizer EPX76. I can't find my manual. I love this calculator and can't live without it. Worried about causing it harm with wrong battery. Any help is appreciated!




1.5 volt button cells:

Silver Oxide, type 357


Alkaline, Type LR44

You may also find type SR44---they should work, too.


Thanks Bill!



There is a site on Internet that specializes in the SR44. As I remember it is www.SR44.com Bulk packed, but prices and service are good.



Also, another note:

I do not have my 11-C manual in front of me, but I remember that in it, HP actually showed that the operating length of time after the battery annunciator comes on, is different for the Siver Oxide (SR44, 357) than it is for the Alkaline (LR44) batteries. (I remember this only because I read it first when I was 14 years old and so it stuch with me all these years. Ah, the young brain.....)

If I remember correctly, the Silver Oxide batteries have longer life, but die in only 30 minutes or so after the battery annunciator comes on, whereas the alkalines have a shorter life, but die more gradually.

Can anyone confirm? (I will re-post this evening from home if my statements are incorrect).




Hi Bill,

The manual says, that after the asterisk first appears:

              Calc ON      Calc OFF
Alkaline > 2 hours > 1 month
Silver ox > 15 min > 1 week

Best regards from V.


If I remember correctly the SR-44 has an anticipated life of about 2 to 2.5 times that of the Alkaline equivalent.
I have used SR-44 in HP-42S and HP-32SII and not noticed that behavior -- however, that does not mean it does not happen. I think the SR-44 is probably more cost effective.

As with anything there are trade-offs.


If you can find them, Vinnic (a Chinese company) makes very inexpensive LR44 batteries. I have seen cards of 10 for between $2 and $3... what a lot of places sell a single cell for. A guy on Ebay seems to always have them at that price. Also Tanner Electronics in Carrolton TX (but he does not do mail order).

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