New M3 battery calibration?

New M3 battery calibration?

New SR+ owner here (3 days), trying to make sense of the energy and battery percentage readings... Stopped at a supercharger today, the battery meter went up to 85%. Drove the car for 15 minutes, checked the trip readings: 6.3 miles, 226 Wh/mi. However, the battery meter dropped to 80% (i.e. by 5%). This makes no sense to me: I spent 6.3*226 ~= 1424 Wh of energy, which should be around 2.7% of the max charge (assuming that the SR+ has a 53 KWh battery). I would expect the battery percentage reading to be a bit more accurate, or could it be that the battery needs to calibrate itself first for better accuracy? If it is indeed calibration, is there a specific calibration procedure / charging pattern that should be followed to help the battery with the calibration (i.e. charge to full, discharge to 10%, etc)?


crmedved | 2019年3月29日

I'm pretty sure the battery percentage it shows you is not 100% of the battery capacity. You can't charge to actual 100% (I think) and you definitely can't deplete it to 0%, plus a small amount may be reserved for "emergency" use to travel a couple miles at low speed (not too sure on that).

Joho.keith | 2019年3月29日

The error bars on short trips can be large. Ignore it and focus on data from longer (50 - 100 mile) trips. I’ve seen this in other EVs and ICEs too.

Alanant | 2019年3月29日

@dpooga Congratulations on the new car.

I had many concerns with the battery range estimates and vampire drain in the weeks after I picked up my M3 Performance+. I had many phone calls with Tesla and three service center visits. They kept telling me that it was normal and that I needed to let the batteries calibrate. They said to come back after 2000 miles for it was still an issue [someone also said 5000 miles]. I was also told to run the battery down to about 10% at least once.

They were right. Estimated range is much more accurate 3000 miles in. Vampire drain has disappeared. We are very happy owners.

Bighorn | 2019年3月29日

Much too small an example for decent results. No reason to delve into bad numbers. Be best.

dpooga | 2019年3月29日

@Alanant thanks, good to hear that this will likely go away after some miles! I'm observing the "vampire drain" problem as well, so this could also be related to calibration...

Bighorn | 2019年3月29日

Your experiment does not require any break in to get accurate results. You need to use much more of the battery to reduce your large error bar.

Carl Thompson | 2019年3月30日

The trip meters do _not_ show all the energy used by your car. Some used energy goes mysteriously missing from the meters and they therefore show better efficiency than the car actually gets.

I noticed the same thing myself:

Other experiments going by what my known-accurate EVSE tells me seem to confirm that what the car's screen says is not really accurate.

pilotsmith69 | 2019年8月3日

I just got my M3 SR+ about 3 weeks ago and I am finding I am only getting about 50 miles for 40% so this means if I dont go under 10% I am getting less then 100 miles but charger??

muhanad.jalil | 2019年11月22日

I received my M3 LR RWD in April 2019 and just lost 10 miles yesterday after I updated to the new firmware. Any suggestions?