Calculate actual energy used to charge?

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olagon

Well-known member
Joined
May 3, 2013
Messages
133
Anyone calculate the actual energy charge from dead to full at various levels?

8 amps at 120V
12 amps at 120V
8 amps at 220V
12 amps at 220V

Read that the car charges more efficiently at higher rates. But just how much more efficiently? And how much energy is actually needed to charge the battery completely?

Thanks!
 
olagon, to answer a part of your question, I just ran out into the garage and measured the following using my Kill-A-Watt and T.E.D.:

EVSEUpgraded Mitsu EVSE operating at "8A" measured 888W at 119.6v (strangely, 888W at 121.6v measured by T.E.D)
EVSEUpgraded Mitsu EVSE operating at "12A" measured 1348W at 118.2v (1.37kW at 121.4v measured by T.E.D)
From memory, my SPX L2 EVSE set to "16A" (i.e., whatever the iMiEV wants to draw) measured almost exactly 3kW at 240v (NOT 220v).

The difference in efficiency between 120v and 240v is probably simply attributable to the voltage drop across the input diodes in the charger: a 1.5v diode drop at 120v is a greater percentage than at 240v. Not enough to make me worry about it.

Somewhere on this forum is the charger efficiency number. Around 85% if I recall. Thus, to answer your question, take power x time x efficiency and get your energy answer. Our 16kWh (nominal) battery is (effectively) somewhat less than that and if you're really interested you might do some poking around on this forum as the answer is here, somewhere...

More significantly, some of us are interested in the overall iMiEV consumption. I kept meticulous track for 8000 miles which yielded an overall wall-to-wheels average of 4.2miles/kWh.

Hope this answers your query.

Curious as to why the question?
 
olagon said:
Anyone calculate the actual energy charge from dead to full at various levels?

16 amps at 220V - 18,8 kWh and 18,6 kWh

I did it twice (SOC 0% car stopped moving after almost 20km turtle to 100%)

My dilemma: is wall to weels efficiency only 85% (16/18,8) or is the actual battery size over 16kWh of usable part?
 
I believe Joe is saying that the car's onboard charger is 85% efficient - Put in 1 KW of AC power (either 120 or 240) and you get out 850 watts of DC power . . . . and about 150 watts of heat, which is taken care of by the cars liquid cooling system

Don
 
Don said:
I believe Joe is saying that the car's onboard charger is 85% efficient
If that's true, it doesn't seem to be a very impressive number... or is it maybe combination of charger and battery losses?
 
JoeS said:
olagon, to answer a part of your question, I just ran out into the garage and measured the following using my Kill-A-Watt and T.E.D.:

EVSEUpgraded Mitsu EVSE operating at "8A" measured 888W at 119.6v (strangely, 888W at 121.6v measured by T.E.D)
EVSEUpgraded Mitsu EVSE operating at "12A" measured 1348W at 118.2v (1.37kW at 121.4v measured by T.E.D)
From memory, my SPX L2 EVSE set to "16A" (i.e., whatever the iMiEV wants to draw) measured almost exactly 3kW at 240v (NOT 220v).

The difference in efficiency between 120v and 240v is probably simply attributable to the voltage drop across the input diodes in the charger: a 1.5v diode drop at 120v is a greater percentage than at 240v. Not enough to make me worry about it.

Somewhere on this forum is the charger efficiency number. Around 85% if I recall. Thus, to answer your question, take power x time x efficiency and get your energy answer. Our 16kWh (nominal) battery is (effectively) somewhat less than that and if you're really interested you might do some poking around on this forum as the answer is here, somewhere...

More significantly, some of us are interested in the overall iMiEV consumption. I kept meticulous track for 8000 miles which yielded an overall wall-to-wheels average of 4.2miles/kWh.

Hope this answers your query.

Curious as to why the question?

Thanks! I asked as I want to create a simply to understand infographic on the cost of charging an EV. This is perfect. Does anyone know if charging efficiency changes over the life of the battery? That is, as the battery's capacity drops, so does charging efficiency?
 
quote="JoeS"]More significantly, some of us are interested in the overall iMiEV consumption. I kept meticulous track for 8000 miles which yielded an overall wall-to-wheels average of 4.2miles/kWh.[/quote]

Does anyone know wall-to-wheels consumption for the Leaf? Thanks!
 
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