Battery degradation, how actually is it calculated?

Moby Dick 6 years ago updated by rn624872 2 years ago 5

This graph is very useful to me.

However, as an electrical engineer, I would be very happy to know how the calculation is processed.

For instance, if I drive using lot of heating / air conditioning, defrost, seat heaters, of course I will consume more energy than when all theses are off.

So, the battery will drain more or less quickly, while same distance has been accomplished.

It doesn't mean the battery is degraded.

So I guess the calculation is based on more specific data that Teslafi can exploit from what you gather from official Tesla data base.

Could you explain this for those who like technical details?

Thank you very much in advance!

Hervé Delétraz

I am a Mechanical  Engineer with a background on Electrical Engineering. We deal with research and studies and development on car efficiency (using gasOline) and when we measure car efficiency we measure by how economical it is such as gallons consumed per mile on a flat surface. On EV’s I believe that when talking about battery degradation we should be talking about how much kwh a battery can hold at 100% full capacity. When you buy a new ev the initial kwh a battery can hold will be what’s stated by tesla and that is the initial capacity in Kwh. After certain number of years the battery deteriorates and you’ll find out that the battery capacity in kwh is lesser than that when it was initially bought as brand new. For example if the ideal battery kwh capacity initially bought was 250kwh and after 2 years you found out that the capacity your battery only added 200kwh at 100%. Then you incurred 50kwh degradation. In the future your car will utimately accept lesser and lesser energy due to battery degradation. Battery degradation is NEVER calculated on its mileage capacity because mileage used is a function of so many variable parameters like speed, battery temp, road conditions, uphill and downhill driving. I hope this will help those who until now could not figure out what battery degradation is. This is how battery degradation is accurately calculated.

So Teslafi just uses the car’s notoriously inaccurate range estimator to report battery degradation?  This is the little battery bar at the top of the screen that you can toggle between % and kilometres. 

Hi, i am at 206/240 miles after since two weeks after I got the car, I have our now 3month old SR+ just installed teslafi to compare with orher, bur can’t it seems... Also I drive kilometers...

Tesla tells me Norhing: capacity is secret and i only deviate 0.4% vs the fleet is what they tell... same mechanic didn’t know what rated range was


The battery degradation report is simply a graph of how much Rated/Ideal Range the vehicle is reporting at 100% or extrapolated to 100% full charge.

So the degradation would be 1.7%(5 Miles) if the vehicle reported a 300 mile range in October and a 295 mile range in December at a 100% full charge.

Hopefully that answers your question.

There's a very large Master Thread on this subject on the TMC Forum that's worth reading.