[bjrosen]

I was wondering what the charging effeciency of the Gen2 Volt is. My EVSE doesn't have a meter so there is no way to know how many KW are pulled from the wall vs how many are stored into the battery. Does anyone have a metered Level 2 EVSE? If so what's the charging efficiency?

 

[hellsop]

Already done for you. https://www.veic.org/docs/Transportation/20130320-EVT-NRA-Final-Report.pdf

 

[davemac616]

My instrumented (by the electric company) Clipper Creek CS40 has done two charges of my 2017 Volt from "empty." The charger reported 15.49 kWh and 15.69 kWh for them with times of 4:09:28 and 4:02:08 respectively. They were both on December 3, the first at 3:22am and the second at 9:43pm.

 

[hvacman]

The EVSE doesn't affect charging efficiency. It is basically just a smart power relay/GFI breaker that turns on/off the AC power flowing to the charge port based on control signals sent to it from the Volt through the charge port's communications terminals. The Volt's internal onboard charger (OBC) is what determines charging efficiency, as it has complex power electronics in it to convert the 120 volt (L1) or 240 volt AC (L2) power from the EVSE to DC voltage matching the battery's specific voltage and amperage charging requirements.

Per SAE paper 2016-01-1129, the Gen 2 OBC efficiency averages 93% with 120 volt AC input and 95% with 240 volt AC input. The attachment provides the details efficiency charts based on input voltage, battery voltage, and charge levels.

 

[bjrosen]

My instrumented (by the electric company) Clipper Creek CS40 has done two charges of my 2017 Volt from "empty." The charger reported 15.49 kWh and 15.69 kWh for them with times of 4:09:28 and 4:02:08 respectively. They were both on December 3, the first at 3:22am and the second at 9:43pm.

Full charge is approximately 14.4 so using your figures, 14.4/15.5 = 93%. That's a little less than the 95% that hvacman quotes the SAE as saying that a Level 2 should deliver but still it's in the ballpark.

 

[16513]

Would full charge kWh not be best calculated using the "kWh used" shown on the leaf display at charge exhaustion? This figure should not vary much from full charge to full charge I would think. No?

 

[bjrosen]

Would full charge kWh not be best calculated using the "kWh used" shown on the leaf display at charge exhaustion? This figure should not vary much from full charge to full charge I would think. No?

Yes, that would be the best way to calculate it. When I did the calculation based on davemac's data I used 14.4 because that's the number I typically see for energy consumption from full to empty but it varies, I've seen it as low as 14.1. For anyone with a meter, please note the amount of KWh used before you plugin and then post both the power used by the car and the power delivered from the EVSE.
Thanks

 

[davemac616]

Ok, my full charge data from overnight:

14.3 kWh used (car's display), 15.73 kWh consumed, time 4:08:56

 

[bjrosen]

Ok, my full charge data from overnight:

14.3 kWh used (car's display), 15.73 kWh consumed, time 4:08:56

So roughly 91%, sounds about right.

 

[davemac616]

Here's a charge from partial discharge, Saturday:

9.0 kWh used (car's display), 10.3 kWh consumed, time 02:46:39 (87%)

Also, my garage is unheated and barely insulated from the outdoors. The temperature inside is about 45 degrees (outside it ranged between 10 and 25 for the weekend). The car stayed on the charger until this morning, giving this additional data point:

0.96 additional kWh over the next 31:09:22