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Tesla Battery Degradation Model

Updated July 2021

Buying a Used Tesla? Use this Model To Forecast the Battery

We have over 20m miles of Tesla driving data and the associated battery range with these miles. In addition to the data, we contacted an ex-Tesla battery engineer who shared academic papers with us that helped us build our battery model that gave us great insights into why Tesla gives some of their advice to car owners.

Tesla Battery Degradation Model

In our model, you can select the SoC, and a set temperature. We have modeled historical temperatures in cities and use that in our model to predict battery health up to five years out, but we have not released it yet.
Note, the age of the vehicle is five years from the start of the vehicle production year. Thus, if you have a 2018 Tesla Model S, in 2021, it will be in year 3 of its age.

Temperature Matters

One of the key factors in the battery range is temperature. The temperature impacts the battery chemistry which can reduce battery range over time. Some of these factors are in the car owners control, and some are not. For example, having a car in a hot weather climate will be worse than having a car in a temperate climate.
Fast charging heats up the battery which also can reduce range if superchargers are used at a high frequency. In our model, we do not let the user select the type of charging that goes on, but if your Tesla or the person who’s Tesla you are interested in buying, connects their Tesla with the Keemut platform, our model takes this into account in predicting battery life and the battery value.

Age Matters

As EVs age, the batteries will degrade slightly over time. Initially there is a fast drop but then it is very gradual over time in a non-linear fashion. This doesn’t mean that an older EV is bad, rather it is just a factor, but not the dominant one in battery health.

SoC Matters

How you charge and the rate at which you charge your battery to, does matter. It is recommended that the charge limit is 90% - 95% by Tesla, and we have seen what happens with Teslas that charge at 99% and 100% often. Those batteries are in relatively bad shape compared to similar Teslas that charge at 90% or 80%.

Looking for More EVs to Add

We have other EVs on our platform including Jaguar, Nissan, and BMW, but we are looking to add more to our datasets. If you are interested in connecting your vehicle, please sign up at Keemut.