Recommendations for how to measure kWh used to charge my model 3 in my condo garage

[hmgolds]

Right. I wouldn't rely on what the car reports if I needed to count the energy consumption for billing purposes. The car only reports energy spent while in drive. It's great to know how much a trip consumed, but not for this purpose. You could camp in the car multiple nights and this would not be accounted for. On top of charging losses, you are missing all the energy while not in drive : camp / keep climate on, energy spent by the car while charging, energy spent in sentry mode, conditioning the cabin, which sometimes also conditions the battery, etc...
As you move your measurement closer to the meter, you'll be more precise. There are devices that monitor energy passing through the wire at the panel but you need an electrician to install that sort of thing and calibrate them. If on 120V, a device on the plug itself should be precise enough. I think that apps like TeslaFi that report the amount of energy put into the car would be close enough. I'm sure there's a little discrepancy from reality but by counting energy that goes in, you're accounting for all scenarios at least.
EDIT: In fact, by looking at the trip meter you could be paying your condo owner for energy that you put in the car at a supercharger. IT makes no sense to me to count it this way...

You're correct; the car won't know whether I'm charging at the condo, a SC, my son's house, or the L2 charger at the grocery store. So that's out. I could, of course, keep meticulous records - but that's not likely.

Besides, one of the drawbacks of condo life is that people should be treated the same. So if the condo accepts individual, non-verifiable accounting from me (which they would) they would have to accept the same from any other EV owner.

So I don't see a good option other than a submeter or a metering charger. Leviton makes a UL Listed submeter (1K240-1SW) that should work. I'd use a UMC with a 6-15 or 6-20 plug (depending on circuit sizing).

But a J1772 charger with integrated metering would be better. Haven't found one that meets all my requirements (which I realize may be too unique):
- usage monitoring without wifi
- hardwired and configurable down to 20amps or using 6-15 or 6-20 plug
- UL listed (if hardwired)

 

[Rocky_H]

You know those old analog electric meters that houses used to use before smart meters and such? You can get those for less than $100 used on Ebay. I would recommend getting one of those and just put it inline with the circuit. Then you can read the usage very directly on the circuit each month.

 

[hmgolds]

Clever idea. The required meter base isn't too expensive. A bit bulky though.