The usual math goes:- 240v * 70 amps = 16.8 kW 16.8 * 3.5 hours = 58,800 kWh… Full pack from empty. But the battery cooling required to maintain this consumes a further ~16kWh. Andrew’s response: The Recharge Energy of 31kWh/100mi is the electricity you pay for from the grid to recharge your Roadster. It works out to ~75kWh of alternating current (AC) for a full recharge. Our ESS (battery) produces direct current (DC) and holds ~53kWh. The difference between these two numbers is due to charging inefficiencies, including the use of air-conditioning to thermally-manage the battery during charging. http://www.teslamotors.com/blog4/?p=60response to the second comment which gives 4.5 hours, assuming that 70 Amps is the limit from the Home Charger. Given that Tesla seem to be sticking with the 3.5 hr figure, how is this being done? All fairly academic anyway, given that owners may not want to "waste" energy on ESS cooling or may not have 70 Amps available - in both cases they would settle for a lower charging rate with smaller cooling overheads.