On Dec 11, 9:45*am, "Bob Mannix" wrote:
"Dave Plowman (News)" wrote in ...



In article
,
* Man at B&Q wrote:
On Dec 11, 1:45 am, wrote:
Why is it that rechargeable batteries state the capacity,eg., 2500
mAh but the 'use once' sort don't?
Probably because it's not in their interest. Better to show bunnies
going on and on...

Also when one question is answered, the next one is raised. And the
next one would be why do so many one shot batteries give only a
fraction of their rated capacity in real life apps. Some questions are
better left unasked.

Is it really true that a primary cell takes more energy to manufacture
than you'll get out of it, or just an urban myth?

I'd bet it is true - and by a factor of many. Then there's the energy used
to transport it etc.

Of course it's true, otherwise the laws of thermodynamics would be in a
pickle and the universe would probably explode fairly quickly as entropy
would be reversed!

Does it take more energy to process Uranium ore than can we get from
using the resulting compound in a nuclear reactor?

Does it take more energy to pick a few lumps of coal off the floor at
an open cast mine than you get from burning it?

If so, these would also seem to put the laws of thermodynamics in a
pickle. Due to natural processes (or divine providence in the words of
the Polish guy on R4 describing his country's abundance of coal) these
substances are able to yield energy to us that was locked up millenia
ago.

It boils down to how much of the energy of a primary cell is put there
by the processing of the constituent chemicals versus the potential
energy in the raw materials. Is it all due to the processing?

MBQ