On Wed, 28 Jul 2010 09:29:14 +0100, Jim Lesurf wrote:

In article , Peter Chant
FWIW later tests and all listening have been with 4 x NiMH AA (1700mAh)
cells as the power supply. These have so far lasted a couple of hours but
I've no idea how much longer they will manage before needing a recharge.

You could run the thing while logging the power drain and when the Voltage drops to 2
or perhaps just 2,5 V just note the time it took to get there. If you have a way to
alert you when a certain Voltage is reached or a way to automatically log voltage
over time.
Or just run it on a speaker so you can hear when it shuts down, and set your
wris****ch alarm for every half hour and read and write down the voltage. I am sure
it doesn't have to be scientific logging. Unless you got equipment that can automate
the process. (That or a teenager in the house with nothing better to do this summer).

-Mikkel