[quote Eugene]The Nissan Leaf is EPA rated at 73 miles per charge and 34 kwh per 100 miles. (This last number may be battery-to-wheels, then wall-to-wheels would be about 10% worse, but let’s go with 34 kwh.)[/quote]
Wall to wheels efficiency is much worse than 90% (your 10%loss mentioned above translated to efficiency.).
Motor electro-mechanical efficiency = 80%(approx)
Battery Storage efficiency = 95%(battery slowly bleeds charge)
Battery charging efficiency = 70% (range is 60% – 80%. This is why batteries heat up when charging – if you discharge your cell phone or laptop and then start charging the battery, it will get warm or hot.. or even explode if its lithium)
DC power supply conversion from AC for the charger = 80%(range is 60% – 95%).
Multiply it out (0.8 * 0.95 * 0.7 * 0.8) = 0.4256 or 43% efficient. I am not including powerline and step-down transformer losses.
Gasoline engine efficiency goes from 23% for the old 1960’s tech to about 40% for current engines. Where electric cars have an advantage is in the regenerative braking. They convert the vehicle speed back to electricity and use it to re-accelerate. A traditional gasoline engine throws the energy out as heat from the brakes.
[quote CDMA Eng]
Suburban driving on a nice day: 105 milesSpeed: Average 24 mph
Temperature: 72 degrees
Climate control: Off
The average speed in this scenario is 24 mph; common when commuting and running errands. The ambient temperature is 72 degrees and the climate control is off. Not using the air conditioner and driving at slower speeds mean less energy use and a little extra range.[/quote]
Did you notice that this had a little bit less of a range from 38mph test listed before – range 138 miles? This is because of braking/accelerating. The conversion of energy in momentum back to electrical – charging batteries and then back out to electrical and momentum. More cycles through the system and each piece of inefficiency in it.
[quote Eugene]But that’s not the entire story. Your PV produces most power during the peak hours, and your EV is charged at night. Unless I’m misunderstanding something, you’d have one meter for the house and one meter for the car. Each kwh produced by the PV system knocks off $0.28 off your main electricity bill, but each kwh pumped into the EV battery during super off-peak hours (midnight to 5 a.m.) only costs you $0.145. So a PV system big enough to power the EV would not just make you energy-neutral, it would make money for you.[/quote]
Yes, no, maybe. The guy who has the website for solarwarrior (listed earlier) noted that the rate change he had for having the electric car also impacted the amount of money he got for selling the electricity back to the net. I guess it was sort of a discounted rate because of the electrical car, so the rate going back on the grid was also discounted. On needs to check with existing rate schedules on the smart meters to find out the reality of the situation.
