Winter charging behavior

[bearswalker]

My new (to me) 2022 MME GTPE and I are going through our first winter together. The car is parked in an unheated, uninsulated, detached garage. There is snow on the ground and the roof. Overnight lows in the low teens (F) last night.

The car is plugged into a Wallbox Pulsar Plus home charger limited to 48A (60A breaker, 100A circuit to garage). The car has been plugged in since the 8th when it started snowing.

After I parked the car and plugged it in, the Wallbox app reported that it took 4.7 kWh. The Ford App reported 3.7 kWh. Nothing alarming to me here.

Since I saw it finished charging, I have noticed the Wallbox app reporting that it finished charging the car (again). Now the Wallbox app is reporting that it has delivered 8.9 kWh since plugging in. The Ford app does not report a change. (I think this is GOOD since I use this number for mileage.) I suspect that the 4.2kWh difference from Wallbox is from the car keeping the HV battery "conditioned" (warm). (Also good since I'm keeping track of cost for power.)

When it was warmer out I didn't see the Wallbox charge again after finishing the first time.

Is my MME GTPE also acting as a space heater in my garage? Not that that's necessarily a bad thing.

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[RickMachE]

3.7/4.7 = 79%. That's way more loss than the 7% it should see. The Ford app is often inaccurate though. You'd want to look at it before unplugging and verify that, and even then it may be inaccurate.

If the temps fall below freezing, the car will pull power for around 20 minutes or so, using under 2kW of power.

8.9 - 4.7 = 4.2. That seems way high for battery warming, and not my experience. Can you see WHEN it took these charges, does the Wallbox app show a graph of the actual charging?

 

[Herbknowsit]

I get similar discrepancy between the Ford App charging numbers and the ChargePoint app's. I go by what the ChargePoint app says it draws for each session when I add up my monthly charging totals. They seem to align more with what I see each day from my home usage totals. So...my total monthly ChargePoint kWh charge totals are always higher than what I add up off the Ford App. And in winter the difference is more.
It would make more sense if I was constantly pre-conditioning or preparing the cabin temps but I'm not doing either very much. I just figured one of the apps was off the mark and so be it.

 

[RickMachE]

I get similar discrepancy between the Ford App charging numbers and the ChargePoint app's. I go by what the ChargePoint app says it draws for each session when I add up my monthly charging totals. They seem to align more with what I see each day from my home usage totals. So...my total monthly ChargePoint kWh charge totals are always higher than what I add up off the Ford App. And in winter the difference is more.
It would make more sense if I was constantly pre-conditioning or preparing the cabin temps but I'm not doing either very much. I just figured one of the apps was off the mark and so be it.

Every charging app records the power that the house is delivering to the vehicle.

The vehicle app records the power it receives. There is a loss.

With 240v charging, the loss is roughly 7%.
With 110v charging, the loss can be 15 to 20%.

So, if your ChargePoint is hardwired at 48amps, 48 x 240 x 93% = 10.7kW. That will vary, because the house is often not delivering exactly 240v, it might be 237 or 243.

With a plug-in 240v at 40amps, it's 40 x 240 x 93% (could be as high as 10% loss so 90%) = 8.9kW.

If you want to track the cost to charge your car, you track what the charger is sending to the vehicle.

If you want to track the efficiency you are getting, you track the energy received.

 

[bearswalker]

Thanks Rick.

Typically the difference between Wallbox and Ford apps is about 0.2 kWh. I expect some loss.

When it was warmer outside the difference didn't change once the car was charged. Now that it's colder out, it seems that the car accepts power (normal battery warming I assume) from time to time as it's parked plugged in, but the Ford app does not report it.

Ideally the app would tell me power used to move/charge the car (and all that entails) AND power used to maintain/warm the car. If I get only one the one I have I is what I prefer for calculation mileage.

I don't see any graphs in the Wallbox app except total charge while plugged in, no starts/stops while plugged in. Wallbox is programmed to charge only off peak (outside 5-9pm). It notifies me each time it "charges," though the charging is less than a minute when it's been parked.

I haven't invested in a recording thermometer, but I'm guessing my garage is a few degrees warmer this winter than it was before the Mach-E arrived.

 

[E90alex]

Yes the car will continue to pull power as needed after a charging session if it’s still plugged in to keep the battery above freezing.

If you don’t anticipate needing the car for a few days you can disable the charger in the wallbox app or simply go unplug it so it doesn’t waste electricity.

There is no harm to the battery to have it sit below freezing, it’s just not ideal to operate it below freezing. So the night before you need the car again, enable the charger or plug it back in so it can warm the battery back up.

 

[bearswalker]

That's good to know.

Does it warm my garage?

 

[Tosh]

Since my wife got her Volvo PHEV and I got my Mach E, our little space heater in the garage has not been kicking on. My thermometer is showing a very steady 60F, when outside it's 38F.

Yes, the cars are helping to warm the garage.

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