On Thu, 4 Mar 2010 15:42:28 -0800 (PST), "hr(bob) "
wrote:

I have a small battery-operated calculator that I rarely use, but when
I do need it, I want to be sure the battery hasn't run down. The
button cell can be a LR54, LR1130, D189, RW89, 389, SR54, or one of
several other codes, Either silver or alkaline. Does anyone know
which type of battery has the lowest internal self-discharge?

I often sort of hate it when people undermine an OP by suggesting
something entirely different from what he wants, so please forgive me
for doing just that.

How about a solar-powered calculator? I have a cheap one that does so
many functions I'll never use a bunch of them that runs off the
ceiling light, or the desk lamp. It may have been 20 dollars, years
ago, when there was a sale at Radio Shack. But no batteries. Here it
is, Radio Shack 10-digit Scientific Calculator EC-4032. It has logs
and trig and exponenets and I got it because it has hex, bin, and oct
arithmetic which I once in a while used as a programmer. Probably
something similar with a different model number now.