I'm sorry, but these calculations are not bourne out by my experience.
A pack left to cycle at 10 amps with the fan accidentally left off will reach an unhealthy 130 degrees farenheit or so (I haven't made that mistake in more than a year), but I've left full packs soaking on a 0.5A trickle for up to six one-hour periods in a row with the fan on and there has been no discernable heat rise in the air being exhausted. My chargers run to delta V and then kick over to trickle for an hour. 20 chargers at once make the air perhaps 1 degree above ambient.
Quote:
Originally Posted by RobertSmalls
A single cell that peaks early will generate enough heat to raise its temperature 22°C/hr. But my assumption here was that there's a good amount of heat conduction throughout a stick on the timescale of interest, so you could model the entire stick as a single thermal mass that rises at one sixth that rate.
Well, that depends on where you live, how you use the charger, and what your goals are.
If you live in the north, then your battery is colder than you like for 4-6mo out of the year. Charge and discharge performance drops off pretty badly as the temperature falls. Below 0°C out, sometimes regenerative braking is too weak to bother with.
If you're using the Insight as a PHEV in the flatlands, where your usage profile is "charge at home, discharge once" with little regen, you'll be interested to know the battery temperature rise will be minimal and the fan will probably never come on.
There's also the small fact that the battery fan draws 0.6A * 12V = 7W. Leaving that on for eight hours a day unnecessarily is like... leaving a light bulb on for four hours a night. I'm the kind of person who will look for an alternative to a 7W load if it's convenient and cheap.
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