Robert Bruninga via EV wrote:
wouldn't it be just as easy to insulate the battery and
provide a small electrical heat source. 100W or so?
Lets say a 1000 lB battery. It takes 1 BTU to raise one pound one degree.
To raise 1000 lbs say 40 degrees from 0F to 40F would take 40,000 BTU or
about 11 kWh. Or about 33 miles of range given up to heat the battery.
True enough if you're warming up a cold battery. But it would be foolish
to heat the battery with its own charge.
Instead, you would use AC mains power to heat it. In that case, you'd be
charging the pack at the same time. So heating the battery from a cold
start just adds to the charging time. When the charge cycle finishes,
you have a fully-charged, fully warmed up battery; so no loss of range.
The battery pack has so much thermal mass that if it is well insulated,
it will stay warm all day, without any supplemental heating. Wait until
the next time it's plugged in to warm it back up.
--
In software development, there are two kinds of error: Conceptual
errors, implementation errors, and off-by-one errors. (anonymous)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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