New Smartphone App "Charging Stats" observations and questions

[rrolsbe]

I monitor the power drawn at the point where my UMC2 plugs in. During the last two charging sessions the KWH's used were the same at the monitor point as the new Charging Stats. Could be off by +/- 1KWH because neither had decimal point precision. The Smartphone app also displays the KWH added for the last charging session in the area where you can adjust the amperage. Since it appears the new Charging Stats is closely reflecting the power drawn from the wall, I hope the other reading is the amount of energy added to the traction battery. If true, the difference between the two would reflect the approx overhead involved during the last charging session (ie.. battery heating, energy required by the car to allow charging, etc.) If the traction battery was cold soaked to a point where several KWH would be required to heat the battery during a charging session, the two KWH values could be different. Maybe someone who lives in a cold area of the country could report the two values after a charging session with a cold traction battery? If this person also had SMT to report the cell temps, that would be plus!

 

[GtiMart]

It's funny... I was trying to help you by looking at TeslaFi...and I live in a cold area. However, I think all I've achieved so far is see that there's a bug in TeslaFi:

Either that or my charging system is extremely efficient Adding more energy than I've used seems off...

EDIT: The value in the Tesla app seemed to be closer to my "Added" value, but it'S tough to extract any conclusion while TeslaFi might have a bug.

 

[jdcollins5]

I monitor the power drawn at the point where my UMC2 plugs in. During the last two charging sessions the KWH's used were the same at the monitor point as the new Charging Stats. Could be off by +/- 1KWH because neither had decimal point precision. The Smartphone app also displays the KWH added for the last charging session in the area where you can adjust the amperage. Since it appears the new Charging Stats is closely reflecting the power drawn from the wall, I hope the other reading is the amount of energy added to the traction battery. If true, the difference between the two would reflect the approx overhead involved during the last charging session (ie.. battery heating, energy required by the car to allow charging, etc.) If the traction battery was cold soaked to a point where several KWH would be required to heat the battery during a charging session, the two KWH values could be different. Maybe someone who lives in a cold area of the country could report the two values after a charging session with a cold traction battery? If this person also had SMT to report the cell temps, that would be plus!

I do not live in a cold area, but I also have the same car as you and a kWH meter on the AC side. I also noticed that the Charge Stats agree with my kWH meter, within rounding. So it appears Tesla is doing the loss calculation correctly. I have charged recently in sub-freezing weather, 20’s F, and the kWH numbers still agreed within the rounding.

 

[nvesprini]

does anyone know how the charging stats values are actually calculated? for example, if the app is reporting that ive charged 50kw does this include efficiency losses from the charger, preconditioning the battery, cabin heating, powering the electronics, etc....or is it that the battery directly took 50kw with all other factors ignored. wanting to pay my fair share for electricity and dont want to undercut what i owe.

 

[RayK]

Not sure of your situation in needing to know exactly how much electricity your charging session consumed (i.e., what you "owe"). I've always assumed that it was the total amount of power delivered into the vehicle. So that would include heating the battery, the cabin and watching Netflix as you are charging. However I might be able to provide an answer or at least get you into the ballpark:

• Charge at a non-Tesla source. By that I mean a public J1772 station or CHAdeMO if you have that adapter. Of course you'll need an account with that provider. I don't think you can trust a Supercharger to give you unbiased information on the amount of power you've used.
• Try to limit the amount of "excess" power you car will use. Turn off A/C, audio system, don't stream anything, etc.
• At the end of the charging session you'll get billed for the amount of electricity you have taken (kWh).
• Compare that to what your app or car says you've received.
• Repeat the charging session but turn on everything you can think of: cabin heat with A/C on, stream videos, etc. Prior to arriving at the charging station tell your car's navigation that you're going to a local Supercharger. That should enable preconditioning.
• Again, compare how much power (kWh) was reported by the charger to what your app/car says.
• This should give you an idea of whether or not the app/car is reporting all power consumed, or just the amount that is going into the battery.

Then again, maybe somebody has already done this and can report about it.