Temp bar data I've witnessed:
2-3 bar transition at -5C
3-4 bar transition at 5C
4-5 bar transition at 15C
5-6 bad transition at 25C
6-7 bar transition at 35C
7-8 bar transition at 40C
And it appears to me,
1-2 bar transition at -10C
8-9 bar transition at 45C
9-10 bar transition at 50C
NB! Limits are strictly Celsius based, not Fahrenheit!
To get to next bar, temperature of the most extreme sensor must go over transition temperature
for example 1 extra degree in case exterior temperature is far from transition temperature, or 2 if very far.
So if it is 20 outside, to get from 6 bars to 7 bars, one of the sensors must read around 36C.
It applies in reverse as well.
If exterior temp is close to battery temp, transition happens right when first sensor reaches limit value.
If exterior temp is way colder than battery temperature, transition to "less bars" happens sooner.
Gen1 Leafs without battery warmer appear to have different limits compared to 2014+, especially at low end.
Newer Leafs should never reach 0bars due to battery heater activation.
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW