Track Mode: Heating and cooling the battery

[ElectrkBugaloo]

When track mode is first engaged you can hear a whine which I assume is it heating the battery.

Can someone explain to me how peak performance in the model 3 battery works? It needs to heat up to a certain temperature to lower impedance -- do we have any indication of the battery temp from in the car (other than the ODB II method)?

Then, I assume, once it gets hot enough it can quickly get too hot, which is where track mode will over clock the AC to try and cool it down?

Again, is there any indication to know when the car is in peak battery temperature range?

 

[Lucky13]

I am not sure but I believe it is always cooling the battery. Unless your car is super cold before you engage track mode. Hmm now you got me wondering, as most times when I use track mode it's right when I am done driving to the track or just getting of the charger so the battery is usually up to temp.

 

[Apprunner]

that loud whirring sound is the compressor at full tilt trying to cool the battery. I think thats why people actually get better quarter mile times in just normal mode vs. track mode.

 

[MasterC17]

Track Mode does not heat the battery, only cools. On-track, the battery/drive units will heat up so fast there is no point to proactively heating them. Drag is a different story, but there is no drag mode.

 

[Street_Tuna]

How many of you guys track these things and run into temperature (high) issues? There is a reason I am asking

 

[Mash]

It is starting to cut power after 2 hot laps. Cool-down lap helps.

 

[MasterC17]

It is starting to cut power after 2 hot laps. Cool-down lap helps.

I haven't noticed the car cutting power due to heat since the middle of last year. The only time I see power drop off now is due to SOC dropping. What temps are you driving in?

 

[Mash]

I haven't noticed the car cutting power due to heat since the middle of last year. The only time I see power drop off now is due to SOC dropping. What temps are you driving in?

It was on a rental M3P in summer 2019 with 85F temps and track is 2.58 miles packed with low speed turns and high-speed straights.
Usually, I have power loss due to temps on Autobahn as well. 10-12 dots maybe.

 

[n2mb_racing]

I didn't notice any power loss with track mode enabled at NCCAR last year. I would do about 10 laps (~20 mi) then pull off to charge / cool.

 

[Mash]

I didn't notice any power loss with track mode enabled at NCCAR last year. I would do about 10 laps (~20 mi) then pull off to charge / cool.

10 non-stop hot laps? Or with slow traffic?

 

[MasterC17]

It was on a rental M3P in summer 2019 with 85F temps and track is 2.58 miles packed with low speed turns and high-speed straights.
Usually, I have power loss due to temps on Autobahn as well. 10-12 dots maybe.

What SOC are you generally at on the Autobahn? The dots can indicate either power loss due to SOC or power loss due to temperature. SMT is a good way to monitor temps. It doesn't seem to be the battery that overheats but the motors.

 

[Mash]

What SOC are you generally at on the Autobahn? The dots can indicate either power loss due to SOC or power loss due to temperature. SMT is a good way to monitor temps. It doesn't seem to be the battery that overheats but the motors.

Driving 145-155 mph after 100% charge it shows dots at ~85% SOC. Slow down to 100-110 mph and it goes away. I didn't have SMT last time I was driving that fast, so can't say whether it was battery or motors.

I still need to put a protection film to do the test, since paint and glass starts to chip off very fast at that speed.

 

[MasterC17]

Driving 145-155 mph after 100% charge it shows dots at ~85% SOC. Slow down to 100-110 mph and it goes away. I didn't have SMT last time I was driving that fast, so can't say whether it was battery or motors.

I still need to put a protection film to do the test, since paint and glass starts to chip off very fast at that speed.

Hmm, interesting. I would be curious to see what motor and battery temps are at those speeds, as well as max power. Thanks for sharing!

 

[Dangerous Fish]

Presumably this was why overclocking was added in TMV2...

"Optimal Vehicle Cooling: Post-Drive Cooling and Compressor Overclock extend track sessions by compensating for the higher temperatures generated by sustained, high-speed driving. Access Post-Drive Cooling and Compressor Overclock from Track Mode Settings."

 

[FlyNavy01]

Compressor overclock was always there for track mode. They just added the ability to toggle it on/off for V2.

I've also experienced power loss due to heat on the track recently. Most I've seen is 4-5 dots and it goes away 20-30 sec after entering a cool down lap. Only seen it in temps above 90F here in FL after 10+ mins of lapping, so not too much of an issue yet.

 

[Dangerous Fish]

Compressor overclock was always there for track mode. They just added the ability to toggle it on/off for V2.

I've also experienced power loss due to heat on the track recently. Most I've seen is 4-5 dots and it goes away 20-30 sec after entering a cool down lap. Only seen it in temps above 90F here in FL after 10+ mins of lapping, so not too much of an issue yet.

It wasn't overclocking before V2 by default AFAIK. Do you have a source for that?
TBH though it rarely gets hot enough here in the UK to worry about that

 

[FlyNavy01]

It wasn't overclocking before V2 by default AFAIK. Do you have a source for that?
TBH though it rarely gets hot enough here in the UK to worry about that

That's a good thing! I've found 65-75F (18-24C) to be ideal ambient temps for the car.

And the original Track Mode blog post on Tesla's website talks about overclocking the AC compressor, as do numerous articles when V1 was first released. That's the noise you hear when you turn it on.

 

[Dangerous Fish]

That's a good thing! I've found 65-75F (18-24C) to be ideal ambient temps for the car.

And the original Track Mode blog post on Tesla's website talks about overclocking the AC compressor, as do numerous articles when V1 was first released. That's the noise you hear when you turn it on.

Ok you could be right, but I read that as it overclocks only when really necessary on V1 (i.e to prevent damage) whereas you can turn it on whenever you want to on V2 (i.e. to maintain performance).

 

[Mash]

Fans were always maxed out in track mode, but whether compressor was overclocked or not before - I don't know. It's possible that within last year heat management was improved. It's also important to switch off AC to not warm up the cooler. Nowadays you don't even need SMT to see what overheats.

Model Y uses larger cooler, so I assume that aftermarket eventually going to make something larger. Or maybe even whole Model Y active shutter cooling unit can be installed to M3.