P3D+ Second Track Day - thoughts

[Odiemac]

For Track Mode, I think Tesla is pre-conditioning the battery and motors by opening up all the coolant passages between them, and using the AC chiller to cool down the system. Supposedly this works for 4-5 straight laps on P3D+ (I haven't verified it yet).

This suggests that the system has some ability to cool the motors, inverters, and battery. It would be great to instrument these various bits on track and see where the weak link is. Tesla has an internal dev mode too that would make life easier, but I doubt they will open access to this.

 

[Lucky13]

Really excited to see what track mode brings out of the car.

 

[omgwtfbyobbq]

For Track Mode, I think Tesla is pre-conditioning the battery and motors by opening up all the coolant passages between them, and using the AC chiller to cool down the system. Supposedly this works for 4-5 straight laps on P3D+ (I haven't verified it yet).

This suggests that the system has some ability to cool the motors, inverters, and battery. It would be great to instrument these various bits on track and see where the weak link is. Tesla has an internal dev mode too that would make life easier, but I doubt they will open access to this.

Tesla submitted or updated a patent on their cooling system to include a heat exchanger between the oil loop for both drive units and the coolant loop for the battery. I believe the limit is that heat exchanger, especially with respect to the amount of heat the smaller induction motor up front generates on AWD cars.

 

[SigNC]

I believe the limit is that heat exchanger, especially with respect to the amount of heat the smaller induction motor up front generates on AWD cars.

this sounds right and I believe is why track mode is going to basically leverage the battery as a heat sink to let you run another 2 hot laps.

 

[kbecks13]

I believe the limit is that heat exchanger, especially with respect to the amount of heat the smaller induction motor up front generates on AWD cars.

this sounds right and I believe is why track mode is going to basically leverage the battery as a heat sink to let you run another 2 hot laps.

Actually i think it's the opposite. They do say that they plan to use the battery as a heat sink, but what that implies to me is that the limiting factor isn't the coolant to inverter plate chiller, but instead is the amount of cooling they can actually do with the coolant overall.

This means that the AC compressor + forced-air cooling of the coolant loop is not sufficient for the heat load being generated OR the heat exchanger for the coolant to air (or refrigerant loop) is not sufficient, but it should mean that the coolant to motor and coolant to battery heat exchangers are big enough (for now). Kinda confusing to type, hope that somewhat made sense...

 

[SigNC]

so you are saying if loop is good enough to Xfer heat from the front motor to the battery using it a a heat sink then really the limit is the cooling of the overall system. I get what you are saying and that does make sense.

 

[omgwtfbyobbq]

Actually i think it's the opposite. They do say that they plan to use the battery as a heat sink, but what that implies to me is that the limiting factor isn't the coolant to inverter plate chiller, but instead is the amount of cooling they can actually do with the coolant overall.

This means that the AC compressor + forced-air cooling of the coolant loop is not sufficient for the heat load being generated OR the heat exchanger for the coolant to air (or refrigerant loop) is not sufficient, but it should mean that the coolant to motor and coolant to battery heat exchangers are big enough (for now). Kinda confusing to type, hope that somewhat made sense...

If I'm understanding what you're saying, I think/guess it could be all 3. I mean, using the thermal mass of the battery pack/cells would help regardless of what the limiting component is, but it's finite and will only help so much. The RWD 3 doesn't seem to have thermal limiting, so the system can likely handle the single PMSRM motor. My understanding was that most off the shelf oil to coolant heat exchangers tend to have lower power transfer rates than radiators because radiators tend to be bigger and are already designed to cope with more power, so I guessed that was the limit, but it could be the radiator or even both.

https://uu.diva-portal.org/smash/get/diva2:825739/FULLTEXT02.pdf

To be honest, even if the limit is both, it could also be because of the size of the induction motor relative to it's power output and efficiency. In that case, Tesla could technically stick a large enough radiator/heat exchanger/oil pump to keep the induction motor cool, but those might be prohibitively large/expensive/whatever because of how small the induction motor is an how much power goes through it.

 

[MountainPass]

@MountainPass How bad was the damage to the fender?

It scraped off some of our 3M protective film from the bumper! And wore away a little plastic from the corner of the bumper. The inner lip of the fender got pulled out a bit since the wheel was turned to full lock, but it bent back without any paint damage.

 

[MountainPass]

Great thread guys, we can't wait to see exactly how Track Mode works. If it really does allow that many hot laps, then our brake upgrade will be even more crucial!

 

[Lucky13]

Great thread guys, we can't wait to see exactly how Track Mode works. If it really does allow that many hot laps, then our brake upgrade will be even more crucial!

Hopefully track mode with some cooling mods via mpp will make the car even more capable to keep at full power during sessions.