And I just learned another tidbit of info from
@AAKEE! I did not realize that the lithium plating occurs more at higher SOCs. So, if you're supercharging a cold battery at low levels, by the time it gets to higher levels, the battery should be fairly warm, no, mitigating some of the risk? So, rule of thumb, supercharge at low levels, cold or preferably warm? Or did I get that all wrong?
Always precondition is my tip.
The battery is not completely safe from lithium plsting at low SOC, but it is less prone to at low SOC.
Lithium plating occurs because the lithium ions can not move fast when the battery is cold. This is the reason why lithium batter Should not be charged at all below freezing.
Even if you connect the travel charger, UMC on a slow power source (L1 in US terms?) the battery will never be charged until it is warmed to ~ a few degrees C above freezing. The reason is to avoid lithium plating.
Tesla reduce the supercharging speed on a cold battery, but I guess there is a compromise between time occupying the SuC and wear on the battery.
I once had to charge on SuC without preconditioning. I always precondition before a SuC session as I have read the research around it.
Tesla updated the UI at Christmas 2021 and I had updated away from home to get to se the Christmas show. On the drive home I couldnt find the superchargers to add a charging, the car headed home on the nav with only a few percent as the target at home. As the temperature dropped 10C to -30C, consumption increased and despite making the navigation over again it didnt add the charger, even when the yellow warning “reduce speed to reach the destination”.
I ended up deciding to need to charge at the SuC 55km from home after actually turning back when the end SOC when below 0%.
My car, having 12-15C temp in the battery and not much energy to heat the battery with went straight up to the maximum ~140kW a Supercharger v2 offers. (Thats 2C)
Looking at research from fast charging and different temperatures you would like the cell temp to be 25C to avoid lithium plating at 1C charging rate.
That did not feel very nice to the battery
-If you need to fast charge a cold battery, just charge what you need, not more.
-If you can, always precondition before.
As it seems, the wear from fast charging, the lithium plating part, might not be shown as a excessive degradation on the battery or maybe not easy detected as degradation but if / when you get enough lithium plating the cells (most likely a few initially) will get short circuit internally, which ruins the complete battery in the model 3 case.
The end state of high amounts of lithium plating is a shorted cell that stops working.
I have an example of a Swedish M3P that was almost onky supercharged. I think he had 55.000kWh supercharging.
The car was around 230K km ODO and out of warranty. He has Scan my tesla and the car had ~12% capacity loss on the NFP (10% loss in range from new).
The battery died and he went to third party shop changing to a used battery.
He was told there was a few cells that had shorted.
My conclusion (not this guys, nor the shop) is that this was caused by extensive supercharging leading to a lot of lithium plating and shorted cells.
So the takeaway is that unlike the conclusion from the articles talking about that supercharging does no harm, it actually does. Just like tesla write in the manual to supercharge when needed but not always.
From the research there is results showing that periods of ”rest” between heavy cycles can male the battery recover capacity by for example reverting lithium plated lithium to cyclable lithium.
I have seen signs of this on both my Teslas, and now I even can predict it.
I recently had a period of higher charges/100% and also several supercharging session’s. There was no time for low SOC cycles between.
Before the capacity was very stable at 97.5kWh-ish. It went down to 96.7kWh during this period and when I had the possibility to use the car as usual, 55% daily with ~ 20-35% end of day SOC the capacity returned to 97.5 kWh.
(First time I did see this a few years back I thought it was a BMS of situation but now I have seen it enough to see the pattern and Im able to forecast it.).
