"Jeffrey D Angus" wrote in message
...


Bill Jeffrey wrote:
OK, I understand that putting it under any kind of load will produce an
erroneous voltage. But if you do pull a few milliamps, is permanent
damage done, or will it recover (however slowly)? In other words, what is
the chemical reaction going on inside the cell? And how does it manage to
continue to produce a VERY constant voltage (plus or minus a few
microvolts!) for years and years, but will be damaged by pulling a couple
milliamps out of it for a few seconds?

From:
http://humboldt.edu/~scimus/Instrume...tdCellDuff.htm

"No appreciable current should be taken from a standard cell, as the
accompanying chemical actions cause more or less permanent changes in the
cell and its e.m.f."

Jeff
Ah, I love those kind of instructions. What do they mean by "No appreciable
current" in this context. Obviously for a power person it would be something
less than a tenth of an amp, while for an electronics person perhaps a
milliamp or so and for a physics person a microamp or less.
I see that for a 10meg input DVM the current would be a bit over a tenth of
a uA. I expect that that must come close to "No appreciable current"!

Neil S.