> Aah, thats what I was looking for! mAh's, I couldnt see anything like
> that on any batteries.  So to get 20 hours, I could put 2 pairs off
> AAA batteries in series, in parallel, so that the voltage is doubled,
> so it the mAh! Thanks for clearing that up...

After V and A, the next thing that might be considered is the
discharge curve of the battery. For example NiCds are good
for short bursts of high energy like power tools, RC models
etc but they run out of puff pretty quickly and they are prone to
self-discharge, IOW they'll go flat all on their own. Other types
like alkalines have a good shelf life (low self-discharge) and
a long flat discharge curve suitable for more general purpose
uses such as clocks, remote controls, etc. This is important
when it comes to choosing batteries for things like low-power
long-life data loggers. Discharge curves are worked out on a
specified discharge current (50mA ??? ), but when you have
a circuit that draws perhaps only 1/100,000th of the battery's
capacity then the discharge curve and the lifetime of the battery
improves dramatically

I have to admit though that there are just so many different types
around now I'd have to hit the books myself to find the right one
for the job

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