Many thanks to everyone's help and advice.
I'll go for three times the usual amount and keep everything within outer
clothing where practical.
James
On 6 December 2010 18:26, Avocet <> wrote:
> > 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
>
>
>
> ------------------------------------
>
> "While a picture is worth a thousand words, a
> sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
>
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>
>
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