View Full Version : ChargePoint question
10-06-2010, 07:08 AM
I signed up for their service in case I ever need to use one of their chargers. They ask
Efficiency: mi/kWh Battery Capacity: kWh
and wasn't sure what to put. Does it matter what I put? Most of their chargers around here are level 1 chargers anyway.
Ballpark: 300Wh/mi, 53kWh.
10-06-2010, 12:25 PM
Thanks. I found this article (http://electricandhybridcars.com/index.php/pages/TelsaRoadster.html) which puts it in the mi/kWh units too at ~4.85 mi/kWh
If you simply took stated range (245 miles) divided by pack capacity ( 53 kWh ) you get 4.6 mi/kWh
Keep in mind that from Chargepoint's perspective it would be how much energy you would take to recharge the car.
Many of the efficiency figures are energy used by the car to go some distance, but there are some extra losses to add in when you take into account that recharging is less than 100% efficient.
10-08-2010, 08:47 AM
Usually, the trip meter shows my energy use between 250 and 270 Wh/mi. That is presumably power out of the battery pack divided by miles driven, or battery-to-wheel efficiency.
If I divide the power I take from the wall by miles driven, it's more like 300 to 330 Wh/mi. That's wall-to-wheel efficiency.
Battery-to-wheel is good for measuring how your driving style/conditions affect range, but for everything else I think the wall-to-wheel number is more interesting.
10-08-2010, 09:29 AM
I signed up and got a little RFID card and an account. The 110 outlet does not have enough room for the Tesla GFCI on the 110 charge cable. I made a very short cable which I can twist into a position which allows the 110 Tesla GFCI to fit inside a ChargePoint station. I've only used one once and it's kind of cool to get an almost real-time report of charge power. However, the numbers were four times larger than real. Their website reported I was getting 7.2 kW during charging which is impossible for a 110v 15A outlet. That was in Healdsburg, CA.
10-10-2010, 10:52 AM
I tried out Level 2 charging at a ChargePoint station yesterday. The car said I was charging at 237V/30A which agrees with the 7.116 kW shown on the charging station screen. The session status screen was also in good agreement with what I expected from the available information.
The full story is here:
An End to the Dark Ages of EV Charging (http://www.saxton.org/tom_saxton/2010/10/modern-ev-charging.html)