> I also rigged an external battery pack that I kept inside my jacket
> to keep
> it warm(er).
That's what we used to do in the BBC Film Unit. The cameraman would
wear a battery belt, but with sound the alternative was usually a sync
Nagra SN recorder under your outer clothing.
I've looked at the Sanyo Eneloop battery specs and the voltage rapidly
falls to 1.1V per cell at -20 C. You need to check the end voltage for
your device. They don't say what the minimum temperature storage limit
is, but if the electrolyte freezes in conventional batteries, they can
be permanently damaged, so protect your spares.
If in doubt, check your batteries (and gear) in a freezer first.
Don't expect to get anywhere near the rated capacity when cold, and
don't charge a frozen battery. The Sanyo graph shows a drop from 1800
mAh to about 300 mAh, suggesting taking 6 times as many batteries than
usual. I know this is plotted at a high current but do you need a high
current to warm the cold battery up?
David
David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce
|