I didn't really have anything to add, but $0.208 / kWh seemed kind of expensive to me since I was under the impression hydro was typically both clean & cheap. Are you sure your rate schedule doesn't look like this (from BC Hydro's site)?
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Not that it changes things all that much, but depending on your baseline energy usage (without EV) it still seems like your worst case scenario is 100% of EV charging being in the $0.1410 / kWh tier. Still, anything in the $30-50 range seems pretty reasonable.
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This is a good simple way to summarize it.
I would just add to your spreadsheet:
You have to include charging losses. For Sentry, the 300W sentry usage in the spreadsheet already probably adequately accounts for charging loss when plugged in, because I believe that is slightly high for Sentry (I can't remember the exact number but it's easily measured).
However, for the driving Wh/mi, if the OP gets 250Wh/mi as indicated in the car, is using a 120V outlet (low charging efficiency; though the fact that Sentry is running during some of the charging time anyway means that you're kind of double counting the inefficiency a little), and is in BC (may have pre-warming expenses, etc.), means that
a factor of about 1.4 should be applied here, taking it to about 350Wh/mi.
Due to substantial overhead of the car being awake and running the charging circuitry, the 120V outlet gives a best-case of about 75% efficiency (thus charging an SR+ 2021 at: 0.75*120V*12A / ((53.5kWh/263rmi)*0.955) = 5.6rmi (displayed)/hr). So I'd expect a 2021 SR+ should show 6mi/hr charge rate
with the doors closed checking from the app (keeps the screen and other stuff off which is absolutely critical for this measurement) when plugged into a 120V outlet at 12A. So that accounts for the majority of that 40% overhead.
The remaining 10-15% overhead on top of overall use accounts for additional pre-warming and stuff which is likely to happen throughout the year aside from the Sentry, and is a rough number. It also accounts for reduced charging efficiency in the winter if temperatures go below freezing in the garage. Obviously it depends how much of that is done. It also accounts for Sentry losses ELSEWHERE and other parking related losses elsewhere away from home which could add up over time (and won't show on the in-car meter).
A good rule of thumb is to
multiply the in-car displayed avg Wh/mi by about 1.5 in very cold climates
(not BC most likely) to account for all of these factors. Lower in other areas, and lower again if using 48A/240V charging (11.5kW) - 11.5kW charging is about 88-90% efficient (and the max 7.7kW charging for the SR+ really isn't much different). But almost certainly much higher than 1.5 using 120V/12A charging in these cold climates because the car has to heat the battery above freezing if kept outside.
The best case scenario scalar to use is about 1.2 in the most mild climates with optimal charging setup (10-12% charging losses, 8% other feature & vampire losses). 1.35 if using 120V/12A.
Of course these scalars depend on mileage driven as well to some extent (because the overhead of feature and vampire loss will be lower for higher mileage vehicles).
I don't know how completely apps like TeslaFi account for this charging loss, but if you go that route you do need to sanity check the settings to make sure it is properly accounting for the overhead in electricity use, if you and your landlord are using that as the metric, and you're both actually interested in making it "exactly" right. There's no reason it couldn't do it, if it can track when the car is awake and the charging circuit is on (because it can track the voltage and current of the equipment that is connected, AFAIK. But not sure how it does that. There is some configuration on the TeslaFi side for this as I recall (people usually jump in at this point and provide the link to the exact TeslaFi setting to play with
).
