Is 1 hour of charging=1 KWH?

I haven't confirmed all the numbers with my actual rates and times, but the advertised charging rate is 12 A at 120 V, and a full charge is supposed to be 5.5 hours. That works out to 7.92 kWh.

 

Charge rate ~= 1.3kW. Full charge ~= 6.3kWh.

 

I took a measurement of the charging power and found it to be 1430 W (which means 11.9 A, very close to the claimed 12A rate). I'm not sure exactly how long a full charge is, but the car is telling me times around 5.5 hours, so a full charge can't be only 6.3 kWh.

 

Incorrect.

Prime full charge | PriusChat

 

I think 6.3 kWh is for L2. Using L1, zero EV range to full charge measured at wall for me has been average 6.7 kWh.

 

I've measured my L1 charge about 6 times, and all were between 6.3 and 6.4kWh. It can be more if you've managed to deplete some of the Hv portion of the battery before you shut off the car.

 

That probably is the reason for the variability I am seeing. I can never pull my car into my driveway exactly when the EV range hits zero. I don't know how you are managing to do that? I always have some amount of HV drive beyond EV range. Depending on a day that is less than 10 miles, but sometimes more. Measuring at wall for L1 charging, I never had a day kill-a-watt meter showing less than 6.5kWh or more than 6.9kWh for a full charge.

 

I'm not - Hv recharges it and my final drive is flat or down so it always ends up at the top of the Hv range.

 

IF the entire 5.5 hours was at 12A your arithmetic would be close to the right answer.
I've read that the last hour is mostly used for balancing the battery and the charge rate is reduced to keep the battery heat in check.

Actual measurements on L1 place the total kWh used at ~ 6.6 for a full charge and ~ 6.2 kwh using L2

OP:
1 kWh after one hour would be true if the rate was 1 kW
My L2 EVSE pulls about 3.6 kW, so about 3.6 kWh every hour.

 

It's more like the last 20 minutes on L2 and 30 minutes on L1.

 

Not being a Prime owner, I can't speak specifically to this car. But for batteries in general, charging power doesn't stay constant for the full cycle, but tapers down as the battery fills.

 

I guess posting a link to the other thread didn't really work, so here's the image:

 

In order for the charge to be only 6.3 kWh on L1 at 1430 W I would have a charge time of only 4.4 hours. That would be consistent with 5.5 hour charging times if it spends an hour doing battery balancing or other lower power activities. I don't have an easy way to measure the total charge energy or produce a clean graph like that one. (I can graph whole house power but not separate the car from other electrical consumption.)

I also find it curious that it was using 4A after it was finished. That seems kind of high for a drain when doing nothing. If it persists at that level for long it would be an argument against leaving it plugged in all night.

 

I didn't read Lee Jay's chart as showing 4A "after it was finished". That looks more like finishing up the charge.

 

An L1 charge takes about 4.5 to 4.75 hours to go from 0% to 100% followed by about 20-30 minutes of taper charge and battery balancing.

During the charge it draws about 10.9A at 120V for about 1.3kW. That's about 6kWh in the full rate charge time. During that last half hour it slowly decreases to about 4A and then stops. The draw when not charging is 2-3W.

 

Correct. 4A is the last rate before it drops to zero, which is the very last sample on the lower right.

 

I almost commented about that last sample at essentially zero, but held off because of the edge artifacts that sometimes show up on various data plots. Glad to hear that it is real, not an artifact.

 

The 7670 second callout is pointing at the last data point.

 

I collected some pretty cluttered data of an L1 charge. (My HVAC system was cycling on and off and shows up in the data.) My charge power seems to be higher than Lee Jay's at 1441 W, so the advertised 12A current. The charge took about 4.76 hrs until it tapered down. I wish I'd checked how long the car predicted it was going to take. Anyway, with that duration the main charge was 6.86 kWh. The charge appeared fully complete around the 5 hr mark. That transition for the last quarter hour is pretty hard to see in my data. If it was simply a linear decline to zero then it adds 0.2 kWh to the charge, for a total of 7 kWh.