- Step 1 - Buy a Kill-o-Watt or similar device which reads amps and plug the L1 EVSE into it.
- Step 2 - Plug car into L1 charger
- Step 3 - Measure current draw (should be around 12 amps)
- Step 4 - Allow car to completely finish charging cycle.
- Step 5 - Use iPhone to turn on heater
- Step 6 - Measure current draw
So, if the current draw from just the heater is less than the current draw from charging the battery, then we'll know that the L1 EVSE is not being used to is full capacity.
However, if you think about it most of your little portable heaters you buy at Wal-Mart for $30 run on regular 110 volt household plus and usually pull between 8 and 12 amps. They also produce quite a lot of heat in order to heat up an entire room. In the case of the leaf, it just needs to heat the interior of the car. So I see no reason why it would need to pull more power than that.
Same true of a window-unit air conditioner. They pull around 12 amps also, so again that should be enough power to cool down a car. Plus I'd be willing to bet the A/C in the Leaf is probably a lot more efficient than a $100 window unit air conditioner.