Submitted by nlukin on Thu, 2011-07-21 18:43
I’ve been very enthusiastic about simplicity and efficiency of electric motor in cars vs heavy and inefficient ICE engine. However one aspect I didn’t see much publicized is the inefficiency of the charging and discharging from Li-Ion battery pack. I wonder what information other forum members have to educate all of us.
To be specific here is an example. Assume my Model S batter pack is completely empty and has a capacity of 42kWh. I plug it in my 220V 50amps outlet in the garage and assume I want to charge it 100%. What will be my meter reading at the end of the charge? Can anyone approximate? I know it will be more than 42kWh, but how much more? The electricity will have to be used for cooling of the battery and for losses during electricity transfer to the Li-Ion cells.
Here is another question. Does anyone know if I choose to charge at 110V 15Amps standard outlet vs 220V 50 or 70amps will one charging method yield smaller electricity losses during charging?
Overall I think we need to account for charging/discharging inefficiencies when we talk about electric cars. ICE engine may be only 30% efficient, but we don’t lose a portion of the gasoline when filling up the tank.
I am a reservation holder of Model S, so please don't attack me for asking this question :)