This first section is calculations based on the cars "self estimate" of how long it will take to charge at the different available charge rates, including an estimate from the MyChevrolet App obtained just after starting the charging session.

At a stop light 1 block from home I took a pic of the charging screen, and it showed that charging at 120V 8 amps would take 20 hours, when I reached home 1 block later it showed that at 120V 12 amps it would take 13 hours, and at 240V it would take 4 hours and 30 min (4.5 hours).

Upon reaching home, I plugged in and let the car start charging on my stock EVSE powered with 240V (240V 12 amps), then I checked the charge time estimate on the MyChevrolet app. The MyChevrolet app said it would take 6 hours.

The following is the cars estimate of charge rate into the battery, and the theoretical draw from the grid at each different charge rate, and the calculated efficiency based on those (no doubt) not so accurate estimates. Also, the charging efficiency calculation is based on the AVERAGE draw from the grid over the entire charge cycle, we know that the charge rate slows down significantly on L2 charging when you get close to 100% So the actual charger efficiency is better than the calculated efficiency based on average draw.

14 kWh / 20 = 700 watts charging rate. Theoretical 8 amp draw from the grid is 960 watts

72.9% efficient, pretty pathetic!

14 kWh / 13 = 1,077 watts charging rate. Theoretical 12 amp 120V draw from the grid is 1,440 watts.

74.8% efficient, a bit better but still pathetic.

14 kWh / 4.5 = 3,111 watts charging rate. Theoretical 15 amps 240V draw from the grid is 3,600 watts.

86.4% efficient, better than the 120V charging... but not as good as claims I have seen here.

14 kWh / 6 = 2,333 watts charging rate. Theoretical 12 amps 240V draw from the grid is 2,880 watts.

81% efficient based on the MyChevrolet app estimate.

Now, in the real world my charging took 5.5 hours.

14 kWh / 5.5 = 2,545 watts charging rate. Theoretical 12 amps 240V draw from the grid is 2,880 watts.

88.4% efficient in the real world on the stock EVSE running at 240V.

Keep in mind I have not yet dug out my volt meter and verified my line voltages. If my line voltage is less than 240V (quite possible) then my efficiency is better.

I will be checking my line voltage on each setup and re-calculating if needed.

I will be doing real world charging test on my ClipperCreek LCS-20P as well, and possibly if I don’t need to go anywhere real quick I will do the 120V 12 amp test…. Not sure if I can make myself do an 8 amp charge test, I am OK with wasting time for “science”, but over 20 hours is a heck of a commitment!

Later,

Keith

PS: Yes I get bored easily