This is excellent insight based on the research, but if someone reads this the last sentences and takes them out of context, please make sure to read the first 3 bullet points in the post as well - best to limit charging to 100% unless you need it avoid the cyclic aging if possible. But if you do happen to charge to 100%, don't worry about leaving it there a bit if you can help it. Doing so should also help the BMS top-balance the pack, too.
I’m not a native english. I do not really get the point, and I’m sure its because of me not reading my post like you do.
For 100% SOC, more or less any research report show less or the same degradation per time unit at 100% compared to 70-80-90%. So in real life we can leave it at 100% for long without any issues.
For the reports showing worse degradation at 100% its more or less at elevated temperature ( 40C or higher).
The increased rate of degradation is not high though:
We can see that at 50C, the increased rate is very slightly increased: 9.5 months at 80% costs 11.5-12% degradation and 9.5 months at 100% costs about 12.5%.
The difference in lost capacity for leaving the battery at 80% for one year and 100% for one year is quite small, even at 50C.
One year is about 8700h, and a extended time like overnight or 10hrs will not wear noticable on the capacity.
There actually is a few research reports that shows that 100% cause less degradation than 70-80-90% for normal temperatures.
In general i try not to promote this idea.
We know the internal resistance increase more the higher the SOC is.
For a EV that is power limited by the battery power like the Tesla model 3 Performance, keeping the SOC low will slow down the reduction of power loss.
We can really leave the car for quite long time at 100% SOC without any clear disadvantage.
This is not related to the “55% SOC limit” as the car actually can be left at 100% SOC for hours without “damage”. Leave it at 70-80-90% and it will take the same “damage”.
As there is no reason to leave the car at 100% after the charging is complete, there will be no recommendation to do this*.
For me, knowing this, I do not leave the car at 100%, but I do not leave it at 70-80-90% either.
The forum rumors (not specifically SM, and not true):
- 80% is the recommended best charging target to “baby” the battery.
- Going below 20% is dangerous for the battery.
- If you need to charge to 100%, drive immediately else the battery dies.
*) I think we should try to separate “best for battery” with “BMS calibrations” as these doesnt really walk hand by hand.