Hi all, I've read various things on the forum about having to charge up to 100% and down low to re-balance the cells/packs and allow the computer to adjust its range estimates.
However has this information been obtained from Tesla or based off recorded data? at the moment my wife charges up to 80% then usually only runs down to about 50% before charging back up to 90% again.
Trying to get the real info on this or if I should just keep going as we are.
I think the two things you mention often get confused, balancing the battery cells and calibrating the range/kWh estimates.
I don’t know of any information either obtained or released from Tesla that talks about the details of how the BMS works. However, there’s folks like wk057 who have done some awesome work to better understand what’s going on underneath the “hood”. What we do know is charging above ~93% is what triggers the balancing between cell packs to begin (charging changes from constant current to constant voltage). From what I’ve read, it’s not fully understood how long this balancing goes (days, weeks, etc.). If you search around these forums, you can get some detailed information on how the balancing is occurring (can’t seem to find the threads right now). That being said, it’s also been discovered this isn’t really something you
need to do unless you’re experiecing issues and/or directed to do so by Tesla. Plenty of us monitor our cell voltage and the BMS does a
very good job of keeping cell voltages across the pack within single digit mV.
As far as calibrating the range/kWh estimate, there’s also some detailed information you can find on these forums but from what I understand, your range estimates are the most accurate when you’re near 100% and 0% SOC. When you’re operating between say, 40-70%, supposedly the range/kWh accuracy can start to “drift” from the true battery levels, thus resulting in a less accurate indication. By charging to 100% and discharging to near 0%, it provides the BMS an opportunity to better understand where the true “limits” are which will provide a better/more accurate range estimation. There have been Tesla service centers that recommend charging to 100% and discharging to lower SOCs a few times for customers experience battery issues. Some folks will see an increase in the rated range after following this process which leads them to believe you’re some how gaining range or that it’s “good” for battery health. In reality, all you’re seeing is a more accurate range estimation.
TLDR: Having balanced battery cells is good for battery health, but there’s nothing you really need to do to “re-balance” your battery unless you’re experiencing issues or told to do so by Tesla. Cycling from 100% to near 0% is simply providing a more accurate range estimate and not something you need to do for maintaining battery health.
Anyways, you’ll find some better explanation in other threads but that’s my caveman understanding of it. All that to say, you should just keep doing as you are.
