[lpmay]

Oh, no doubt heat is also not good for batteries (neither is the cold). I didn't mean to imply it wasn't.

However I'm still not sure heat is the first order effect limiting charge rates. If you consider that the charge efficiency of the cell is something around 99%, the total losses at a 1C rate relative to the thermal mass of the cell are pretty negligible ( nominally, around 3.6mW per A of charge current ). I'd wager that when your cellphone heats up under charge, that's primarily due to losses in the ~90+% efficient charger circuitry. Heat is heat, and that is still not good for the battery of course. I believe the cooling system in the Tesla is primarily for when the cells are being discharged, but it would be really interesting to hear the full story on that from a Tesla engineer.

I found the below link which also seems to imply the lithium plating as well as other chemical effects are the first order issues. http://batteryuniversity.com/learn/article/bu_808b_what_caus...

[tjoff]

Thanks, I feel there is something missing when translating the stress tests made in that article to consumer peripherals. I get the impression that longevity is greatly sacrificed for short term performance in phones and laptops. But that is just me trying to explain why (my) phones and laptops loose their battery capacity so quickly.

Regarding Tesla supercharging I found this: https://www.teslarati.com/watch-tesla-battery-thermal-manage...

I also heard of issues of other cars (don't remember brand) who can't perform a supercharge - some driving - and then another supercharge because the batteries would overheat (still from the previous supercharge), preventing long trips.

[lpmay]

Yea, it's quite possible that something changes at these (scary) high charge rates. Maybe charge efficiency takes a nosedive, or there are some other effects that are non-linear with charge rate. Thanks for the link.