efficiency losses

[Maquis]

The receipt from Ford shows the price and kWh provided by the CPO.

The Ford app shows the kWh that was calculated by the truck.

For my recent IONNA Janesville charge, the Ford receipt shows 90.259 kWh for $21.75, and the Ford app shows 89.2 kWh added as calculated by the truck.

90.259 * $0.20 = 18.05 * 5.5% sales tax (WI 5% + Rock County 0.5%) = $19.05 + $0.03/kWh WI charging excise tax = $21.75

So the calculation seems right to my non tax professional eyes.

The kWh on the receipt should generally be larger than the kWh in the Ford app charge history tab because the truck doesn't know about losses between the metering device in the charger and the battery pack in the truck.

That’s reasonable, a little more than 1% losses in the truck. The OP’s numbers reflect 12-13% losses.

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[DavidS]

All of the heat generated in the battery during charging is resistive heating (watts of power dissipated into heat) and then the cooling system has to expend energy to remove that heat. One reason the Lightning throttles charging over 80% state of charge is that heat generation (battery resistance) increases greatly over 80%. Keeping your DC charging below 80% will vastly reduce the difference between stored and delivered kWh and save you money.

 

[TaxmanHog]

I don't live close to an Ionna DCFC but was curious how data reporting accuracy is with other systems, so I took advantage of the EvGo memorial day free credits this afternoon, at a 50KW terminal at the local mall in North Attleboro, Mass.

The EvGo sales report shows 29.419 kWh delivered, while the final charge record in Ford App showed 31 kWh, funny that it's slightly more than the provider says they sent, ironic.

This was a snap shot of the in process session screen from Ford App at 89% only 30 seconds or so later went to 90%

 

[jwrezz]

All of the heat generated in the battery during charging is resistive heating (watts of power dissipated into heat) and then the cooling system has to expend energy to remove that heat. One reason the Lightning throttles charging over 80% state of charge is that heat generation (battery resistance) increases greatly over 80%. Keeping your DC charging below 80% will vastly reduce the difference between stored and delivered kWh and save you money.

I was at a memorial day memorial service that was just down the road. I left the truck on the charger until it was at 96%. That last 16 percent must've been the extra loss.

 

[jwrezz]

Years ago I remember a big scandal over gas pumps not being calibrated properly charging people more and giving less than advertised, I wonder if that could somehow be the case here.

I wonder if NIST and state/local offices of weights and measures have authority over this?

Quick research before I hit "post" shows public utilities commission governs electric meters.

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