Proving Minimal Charge Loss for the Tesla

This is part of a series that covers my experience with a Tesla Model Y.

One of the reasons I have some data capture taking place on my own systems is in case some vendor I use has a DR event. That might cause me to lose some data, since I’d be depending on them to keep the data around. If I lose my system, I can always (hopefully) go get their copy again.


Who knows.

In any case, my wife and I spent the weekend in LA, coming back Monday. We got home from the airport and my wife said the Tesla was really low. The charge level was at 22%. She thought sitting parked at the airport from Fri-Mon drained a lot of charge. I countered that it hadn’t lost much of anything.

I had actually left home Tues morning and returned late Thur, so I hadn’t driven the car (or plugged it in) since Monday. My wife said she hadn’t driven much, so there should be more charge.

To settle the situation and understand, I turned to my Teslamate data logger. It’s been running in a container on my machine (Actually a few) and keeps the data backed up.

If you look at the charge level, you’ll see that I got up to the 76% level (the max setting for us) on Monday.

2022-08-17 13_39_55-Charge Level - Grafana — Mozilla Firefox

I was in Seattle at 12:50p Tuesday when someone started driving it around. The normal driving that day took the charge down to 59%. I’m guessing a few errands throughout the day.

2022-08-17 13_40_05-Charge Level - Grafana — Mozilla Firefox

Then this remained the state until Friday morning just before 9a. That’s when I left for yoga, and you can see I drained down some charge.

2022-08-17 13_41_40-Charge Level - Grafana — Mozilla Firefox

I got home and plugged it in, but because I have this set for overnight charging, nothing happened at first. I finally remembered to click “start charge”, but only added 2″%.

2022-08-17 13_42_15-Charge Level - Grafana — Mozilla Firefox

That’s what we took to the airport. The drive up drained the batter down to 41%, and I’m guessing another % went down with cabin overheat running. This runs for a bit of time after the car is locked (it was hot in DEN). The charge remained at 40 through the weekend until Monday morning.

2022-08-17 13_43_24-Charge Level - Grafana — Mozilla Firefox

Driving home was the dip down to the 22% where we ended up in the right side of the graph above.

Not that I wanted to win an argument, but more verify that what I told my wife was correct. We have sentry off and we should lose minimal charge from the car being parked.

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2 Responses to Proving Minimal Charge Loss for the Tesla

  1. JeffModen says:

    I love it. It reminds me of the computational world where people make all sorts of wild performance, accuracy, and other “Best Method” or “Best Practice” claims that, with just a little code to prove it, blows them out of the water. And, in the world of SQL Server, “charts” are not proof without the code. I always want to see the test code to create the data and run the tests.

    Yes, I understand that for something like this, there is no code to create the test data or create the charts but I agree that both are well known and previously proven for accuracy. I just wanted to agree that without this kind of proof, claims otherwise are incorrect.

    Nicely done.


    • way0utwest says:

      Thanks. I haven’t shown this to mrs way0utwest other than the middle graph showing no loss at the airport 😉

      I’ve liked your approach often to performance things, and I question many numbers these days, but cause often it’s based on a very small sample size (1 or 2) or a guess rather than actually digging in.

      This also seems to pervade many arguments on the Internet in all aspects of life. Too much conclusion with little data.


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