App Charging Stats vs Wall Charger Stats

[drb116]

Every month I log the charging stats from my Tesla Wall Charger to get an idea of how much of my electric bill is going to the car. With the new Charging Stats on the app, I figured it could replace this habit, however when I looked at the numbers, they are pretty far off.

According to my wall charger, I have used 302 kWh in the last 32 days, but the app Charging Stats state I have only used 256. I could understand a slight difference, but it is a good 25%.

Has anyone else seen this or know what might be causing the difference? I know it is not timing as I don't actually have any charging the first couple or last couple of days of the 31 day period.

 

[nvesprini]

could this be efficiency and overhead losses? ie: your battery actually took in 256kw as reported by charging stats, but that doesnt include efficiency losses (i think around 15%) as well as powering the cars computers during charging, any preconditioning and cabin heating, etc.....all power that wouldnt have gone directly into the battery. ive just posted a question on this in another thread so hopefully someone can confirm how the charge stats is calculated.

 

[buddhafree]

I have 21.7% difference in kWh usage between Tesla app and power meter. Likely a combination of efficiency losses and some electric usage when electricity is not being supplied by the battery but taking directly from the house.

 

[rrolsbe]

If you do not precondition the traction battery or run the cabin heater while plugged in, the app appears to be fairly close. I am not sure if the energy used to heat the traction battery, to allow charging, would be included in the app stats? The battery cell temps have not been below approx 43.5F during any of my recent charging sessions so no heating was required