12 kWh to charge from ~80% to full?

jeffy1021 said:

I have had my e-Golf for about a week. Yesterday I charged at a L2 station to about 80% before heading a few miles back home. When I got home, I plugged in using the L1 EVSE that came with the car and left it plugged in overnight. The next morning, I noticed my watt meter that I had connected to the EVSE showed 12 kWh used which seems rather high.

In theory to charge the remaining 20% of 21.1 usable battery capacity needs 4.22 kWh. And assuming an additional 20% loss at the L1 EVSE, that comes to about 5.2 kWh needed at the wall to charge to 100%. Regardless, I probably won't be charging to 100% regularly unless I really need the range the next day but I still wonder about the high energy usage to get from 80 to 100.

I am not using any delayed charging settings, but I might have set the minimum charge setting via the infotainment system to 100% when I was playing with the car. Not sure if that affects anything if I am not using any departure settings.

Any thoughts on this?

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JoulesThief said:

Unless you have a kwh meter that only measures what you have plugged in, your measurement is incorrect at your existing meter. You indeed should have added about 4 to 4.5 kw. There is about a 8 to 10% loss of energy in recharging that the battery takes on vs what it takes at the meter to recharge it. Heating losses and such, as well as the EVSE device itself draws power too. Best to do full recharges at the L2 if you have the time.

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jeffy1021 said:

JoulesThief said:

Unless you have a kwh meter that only measures what you have plugged in, your measurement is incorrect at your existing meter. You indeed should have added about 4 to 4.5 kw. There is about a 8 to 10% loss of energy in recharging that the battery takes on vs what it takes at the meter to recharge it. Heating losses and such, as well as the EVSE device itself draws power too. Best to do full recharges at the L2 if you have the time.

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I have a Kill A Watt meter that is only measuring power used by the L1 EVSE.

http://www.p3international.com/products/p4400.html

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JoulesThief said:

jeffy1021 said:

JoulesThief said:

Unless you have a kwh meter that only measures what you have plugged in, your measurement is incorrect at your existing meter. You indeed should have added about 4 to 4.5 kw. There is about a 8 to 10% loss of energy in recharging that the battery takes on vs what it takes at the meter to recharge it. Heating losses and such, as well as the EVSE device itself draws power too. Best to do full recharges at the L2 if you have the time.

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I have a Kill A Watt meter that is only measuring power used by the L1 EVSE.

http://www.p3international.com/products/p4400.html

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Be careful with that kill a watt meter, you are right at the limits with using it with your supplied EVSE. I know, I burned mine up doing what you are doing... poof, blue smoke. Pulled it out of my travel trailer to measure, and it melted and shorted out. It was a mess getting my plug out of it and cleaning the plug up again. No melting or distortion or anything on the EVSE plug. My L1 was pulling right at 1400 watt hour, at 122V.

Did you have any interior cabin preheating features on while recharging? Was the car door locked while recharging?

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jeffy1021 said:

My EVSE is 12A at 120V and the Kill A Watt says 15A max so I think I do have a little headroom.

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mfennell said:

jeffy1021 said:

My EVSE is 12A at 120V and the Kill A Watt says 15A max so I think I do have a little headroom.

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I thought so too but the Kill-A-Watt is definitely not capable of day-in day-out usage at 12A. Mine eventually melted down when I had a Volt (same 12A rate), damaging the EVSE plug as well.

EDIT: I recall that the Edmunds guys melted down a Kill-A-Watt during their testing too.

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jeffy1021 said:

mfennell said:

jeffy1021 said:

My EVSE is 12A at 120V and the Kill A Watt says 15A max so I think I do have a little headroom.

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I thought so too but the Kill-A-Watt is definitely not capable of day-in day-out usage at 12A. Mine eventually melted down when I had a Volt (same 12A rate), damaging the EVSE plug as well.

EDIT: I recall that the Edmunds guys melted down a Kill-A-Watt during their testing too.

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Thanks for the tip, I'll be sure not to leave the Kill-A-Watt connected to the EVSE for extended periods.

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