strider
Active Member
Good info @theatrus. With Li-Ion, you have 2 things that degrade a pack (well, there is a 3rd one, temperature, but it doesn't affect Teslas since they manage the pack very tightly): charge cycles and calendar degradation. Charge cycles are self explanatory. The batteries are only designed/tested for a given number of cycles. You only control this by how much you drive. With calendar degradation, it is the slowest at 50% SoC. If you are going to store your car for a while, you should set it for 50%.The main thing to avoid is charging to 100 and leaving it there often (doing it for a road trip is fine) or leaving it at 0. I leave my M3 plugged in at home at 80%.
As for 70/80/90%, it’s really up to you and how much you may drive daily or on a whim. There is theoretically less battery degradation from using 70% over 90%, but we are taking a few percent over the life of the car. You can start with 80% for daily driving and see how it treats you.
It is easier for the BMS to balance the pack at higher levels (because the cell voltage changes are larger so easier to detect). With our cars I set it for 90% and charge 1/week depending on driving. But we don't have surprise long drives.