How do I gauge my battery health, while also not obsessing over it?
So I just picked up my 2021 model 3 on Wednesday, and it’s been amazing. But my only concern so far is the battery health. It’s a long range awd (I tend to take business and personal trips and wanted an ev that could do that), and at 80% charge, I was sitting at 266 miles, which if my math is right was about less then 10% degradation.
I was really happy with that math until I noticed today a 26 mile drive cost me 50 miles of range, and a 1 mile drive cost me 4. The math ain’t mathing anymore. Is this normal? I know there will be some loss range over AC (I am in Texas) and sentry mode, but almost two miles for every one mile??? That seems odd/bad.
Is this normal?
Completely normal, battery "miles" do not equal real world driving miles. AC uses "miles", sentry mode uses "miles", everything is using "miles'. If you run sentry mode for a few hours you will use tens of "miles" but the car hasn't gone anywhere.
Most people like to switch the display to % and stop worrying about state of charge expressed as fake "miles", it reduces your tendency to obsess over it.
But to answer your question, the only real way to judge battery health is to run the battery health test from the service menu, which can take up to 24 hours and you need to be plugged into a level 2 charger. It most cases its unnecessary though, it wastes power, deep cycles your battery which isnt the best thing for it, and ends up telling you what you already knew.
There's so much that goes into battery usage, just like fuel, but for whatever reason we don't pay attention when it's gas. Temperature, HVAC usage, uphill/downhill, how hard you accelerate, etc.
Subscribe to TeslaFi for a month and there's a battery health gauge that compares your car to all the cars that use that program. That's really the only thing you can do.
Don’t even look at miles. Just keep it on percent. If you’re worried about battery health, take it in for a checkup
Run your battery down one day below 20%. Then charge it up to 100%. See how many kW you added to car. Add back an estimate of how many Kw where already in the battery. There you have a fairly accurate way to validate the capacity of the battery.
Then with that capacity you can go to the energy screen and estimate true miles based on your efficiency. Knowing that there will be some loss for other things not specific to driving (AC, sentry mode, etc )
You can run a battery health test in service mode. You can see people running the test on YouTube. You will need a level 2 home charger and lots of time.
You are conflating two different topics:
Does the battery hold as many kWh as it used to when it was new?
Does the car drive as far on a kWh as you expected?
You need to look at those separately.
If you look at your range on the battery meter when charged to 100%, you will get a pretty good idea of (1), at least if you know what the battery meter used to show when the car was new (many people don't, and start jumping to wrong conclusions).
However, this will tell you absolutely nothing about (2). Also, driving shorter on a charge than you expected, will not tell you much about (1).