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Discussion Starter #1
Hi, long time lurker but finally joined since I bought my Bolt LT 3 days ago. Still charging from 110v 8 amps but noticed an interesting discrepancy. I took a short 10 mile trip (5 miles each way) today from a full battery. The car says I used 2kwh but to charge it back to full I used 4.4kwh (measured using a smart plug).:eek:
I know there's electricity lost going from AC to DC but that seems a lot. Can anybody explain to me the difference?
 

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I tried to search online whether the smart plug itself might be the cause. The one I have is rated 10-15 amps but it doesn't say if it'll add to the power used when charging. Does anybody use a smart plug with their Bolt or Volt?
 

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I tried to search online whether the smart plug itself might be the cause. The one I have is rated 10-15 amps but it doesn't say if it'll add to the power used when charging. Does anybody use a smart plug with their Bolt or Volt?
I use a Charge Point device and if the car says it used 20 kWh, the Charge Point might say it used 21 kWh to recharge, so it is close. Try putting on more miles before recharging and see if it comes closer. The flow display shows the battery charge in 20 bars for 60 kWh, or 3 kWh per bar, which seems quite accurate.
 

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Batteries are least efficient at charging as they approach full charge. The charge rate itself is slowest near the end. During the slow charge phase, fans or pumps might have to run to regulate temperatures of the battery or charging electronics. This might explain some of the discrepancy between what was consumed, and what it took to charge back up.

I seem to remember charging on 120v on the Prius was about 70% efficient. Your discrepancy doesn't sound right.

Try to replicate that again, and make note of how long it takes to terminate charging.
 

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The few times when kEVin went to a public e-Trough the dispensed kWh on the charger counter was always higher than what the car said it took up. But I suppose no process is 100% efficient, so perhaps some discrepancies may be due to that.
 

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Discussion Starter #7
Batteries are least efficient at charging as they approach full charge. The charge rate itself is slowest near the end. During the slow charge phase, fans or pumps might have to run to regulate temperatures of the battery or charging electronics. This might explain some of the discrepancy between what was consumed, and what it took to charge back up.
That seems to be right. I didn't charge my Bolt for about 80 miles (3 days worth of driving) and today charged it for 3 hours, which netted about 12 miles when tallied by the myChevrolet app. From my driving habits it calculates that I drive 4-4.5 miles on 1 kWh, so I probably charged about 3 kWh in 3 hours which is more appropriate. So to save power I guess I'm never going to charge it to full unless I really need the full range.
 

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Discussion Starter #8 (Edited)
The last kWh seems to be the "problem"

Did some testing with a short charge (used 1kwh) and a longer charge (used 8.1 kWh). The juicebox pro app logged 2.2 kWh charged for the first case and 9.2 kWh for the second.
It seems that the last kWh to tip off the battery to full explains the discrepancy. In the 8.1 kWh case, the chevy app says that at 8.4 kWh it was full already, but the car didn't stop charging (slower but still charging) until it went to 9.2 kWh.

So it might be better to stop the charging when it starts slowing, if you don't really need the battery to be completely full.
 

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