Charging efficiency?

Charging efficiency?

Has anyone measured charging efficiency on their model s? Ie. to get say 50kw of power into the battery packs, how much wall power does it actually use?

Related, does the battery cooler run during charging? Ie does charging cause the battery pack to heat up enough to require the battery cooling system to run?

olanmills | December 9, 2012

I can't find the source, but I remember Tesla saying that it was pretty efficient, like close to 90%. Hopefully someone can confirm.

mrspaghetti | December 9, 2012

Says 92% peak efficiency, whatever that means.

Timo | December 9, 2012

With SC battery cooler is a must. Even with 92% efficiency 8% out of 90kW is 7.2kW which is quite powerful heater.

Yet another reason to make batteries liquid-cooled, I don't think something air-cooled like Leaf battery could handle that much heat.

nickjhowe | December 9, 2012

@Timo - Remember the A/C to DC conversion is done offboard with SC - it is pumping DC directly to the car and the batteries. The main inefficiency (and heat output) might be in the SC hardware itself rather than in the car.

mthanos | December 10, 2012

There are two inefficiencies to consider. The inverter is stated to have a 92% rating but the batteries' own internal resistance times the charging current squared will be it's loss in watts. We'll probably have to measure the efficiency empirically. However, anyone who has used a SC can comment on the operation of the car as it charges: Does the cooling system for the battery run like he'll when connected?

nickjhowe | December 10, 2012

@mthanos - I agree and should have said that the batteries are bound to still heat up during charging. No idea how much heat they need to dump.

ptrubey | December 10, 2012

Actually I was wondering if the cooler ran during normal charging - ie from a 50A 240V plug.