I'm trying to work up formulas for calculating how long it'll take me to drive long trips that require at least one charge mid-route. Figuring out the Wh/Mile at a given RPM is easy. Figuring out how much of the kW flowing into the car actually end up increasing the kW stored is an unknown to me. Does anyone have information to help me out? For instance, the public HPC in Atascadero runs at 240 volts, 70 amps. That's 16.8kW, but if my Roadster's battery's SOC is 22.4kWh, I know that after 2 hours the car won't be full (56kWh). The car charges faster at low SOCs. I know there all sorts of factors, such as the battery temperature (cooling the battery while charging takes away some of the power that would otherwise go into the battery). I'm not looking for exact answers, just good enough to help me plan. Any practical information to help me formulate how long it'll take to charge the Roadster given a reasonable number of reasonably known variables would be much appreciated. I'll post my final equations for review and comment here. thanks!