The data indicated that the Tesla batteries lose less than 10% of their energy capacity after 250,000 km. Tesla owners are gathering data on batteries from more than 350 Tesla vehicles all over the world and giving a compiled result. The group is updating a public Google file to keep their research updated. So far the results show that for the first 100,000km, Tesla battery packs lose almost 5% of their capacity. However, after this drop-off, the capacity levels out and the batteries rarely degrade to another 5% after that.
The trend shows that the average battery pack can cycle through over 300,000 km before coming close to 90% of the capacity. There can be many reasons for this including frequency of DC fast-charging and daily state of charge. Jeff Dahn, a renowned battery researcher at the Dalhousie University, recommended that Tesla owners only charge to 70% daily to extend the battery life. Tesla made it clear to Model S and Model X owners that they will not cover battery degradation from ‘battery usage.’ The car’s warranty states, “The Battery, like all lithium-ion batteries, will experience gradual energy or power loss with time and use. Loss of Battery energy or power over time or due to or resulting from Battery usage is NOT covered under this Battery Limited Warranty. See your owner documentation for important information on how to maximize the life and capacity of the Battery.”
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However, for Model 3 owners, Tesla has another warranty which includes a new 70% battery capacity retention guarantee. This warranty can be offered to lucky Model 3 owners since the car is equipped with different battery cells and a new battery pack architecture as well. The existing data coming from the Model S shows that there is no risk of major degradation. Battery degradation can be a serious concern for electric vehicle owners as people are considering to switch.
The Nissan Leaf, world’s most sold electric vehicle has a very poor degradation rate. The data shows that the original 24 kWh pack loses about 20% of its capacity in almost 5 years and the 30kWh battery pack loses capacity even quickly. Tesla has spent a lot of time and money researching their batteries and the results show their battery quality as well. Elon Musk once boasted that the company has tested a battery by simulating over 800,000 km on it. According to him, the battery was still operating at 80% of its original capacity. However, there is no Tesla out there to prove this statement.