Re: Li-Ion batteries

In article <VA.000002f5.014666a5@xxxxxxxxxxxxxxxxxxxxxx>, Roderick Stewart
wrote:
In article <rpCdnWUjW42OMSfanZ2dneKdnZydnZ2d@xxxxxxxxx>, Bill Wright wrote:
     Lithium-ion batteries limit self-discharge to less than 5% of the 
original capacity per month when batteries are stored at 20°C.
 
This is making me wonder if the spec is telling porkies. It might have 
been -10 here, but not -20.

I'd advise being very suspicious of any battery specs, unless they describe 
all the conditions in great detail. I once designed something that was 
calculated to run all day on a 12V Dryfit battery (lead/acid with a gel or 
paste electrolyte) - but it didn't. When I tested these at room temperature 
down to a cutoff voltage of 10.5V at about 1A (which I thought was quite 
generous of me) I couldn't get any more than 10Ah from a brand new one, and 
of course they'd get worse with age.

Silly me, I thought I'd put the specified capacity of the battery, which was
15Ah, so being unable to get anything more than two thirds of that from a
brand new one at room temperature was quite an awkward discrepancy.

Rod.

.

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