Cooling Battery Cells vs Battery Packs

[thelastdeadmouse]

I'm curious is anyone knows, when Tesla packs overheat, is it primarily a limit of the cooling system design for the pack coolant (radiators, coolant capacity), or is it more limited by heat transfer rate at the individual cell level? The reason why I'm wondering is that if is a matter of heat transfer rate from the individual cell to the coolant, what effect could the slightly larger diameter of the new 2170 cells have vs 18500 cells for maximum discharge rate? Obviously the larger the diameter, the lower the ratio of surface area to volume, the less heat transfer area per kWh.

 

[JohnSnowNW]

I'm not familiar with Tesla packs overheating. Are you sure you're not thinking of the motors?

 

[jkn]

I'm curious is anyone knows, when Tesla packs overheat, is it primarily a limit of the cooling system design for the pack coolant (radiators, coolant capacity), or is it more limited by heat transfer rate at the individual cell level? The reason why I'm wondering is that if is a matter of heat transfer rate from the individual cell to the coolant, what effect could the slightly larger diameter of the new 2170 cells have vs 18500 cells for maximum discharge rate? Obviously the larger the diameter, the lower the ratio of surface area to volume, the less heat transfer area per kWh.

I don't know, but I guess problem is in too small radiator. If not, they have a problem: http://www.electricgt.co/p100news

 

[jaguar36]

If you try to take an S to the track basically everything overheats, the rotor and the stator first, then the inverter and then the pack. They all cool at different rates so its possible to overheat one and not the others if you are doing a certin combination of power on/off. Pack takes the longest to cool down and its a combination of the cooling system and the cell size. Lower coolant temps will cool the cells faster regardless of if they are bigger or smaller, so smaller cells would help, but so would a more capable coolant system.

Bottom line the S was designed and optimized for street use, not the track. The 3 is likely to be the same, so don't expect to be able to track it with any success.