Delay Power Limiting By Running The Heater?

ratsbew · Dec 13, 2014

Will running the heater on full blast allow you extended track time by removing extra heat from the motor and battery?

My understanding is that the Model S uses a regular resistance heater to heat the cabin when there isn't any waste heat available from the powertrain. After the powertrain warms up, that heat is available to heat the interior.

Does anyone have experience with this? How about experience pushing the car on the track in very cold temperatures?

ecarfan · Dec 13, 2014

I was not aware that the S ever used "waste heat from the powertrain" to heat the cabin. Is that correct?

I thought all cabin heat came from a resistance heater dedicated to only providing heat to the cabin. But of course I could be wrong...

pgiralt · Dec 13, 2014

I think there's a way to get the heat from the power train into the battery. If you look at this picture:

http://www.teslamotorsclub.com/attachment.php?attachmentid=52657&d=1404144679

You can see the little box on the left side. I think that's capable of redirecting the outside loop into the battery loop - but I'm not positive.

freds · Dec 13, 2014

ratsbew said:
Will running the heater on full blast allow you extended track time by removing extra heat from the motor and battery?

My understanding is that the Model S uses a regular resistance heater to heat the cabin when there isn't any waste heat available from the powertrain. After the powertrain warms up, that heat is available to heat the interior.

Does anyone have experience with this? How about experience pushing the car on the track in very cold temperatures?

Actually I think you want to run the air-conditioning at full blast. I made the mistake of turning it off thinking I would get better times; but it went into power limiting real quick.

Doug_G · Dec 13, 2014

ecarfan said:
I was not aware that the S ever used "waste heat from the powertrain" to heat the cabin. Is that correct?

Yes it does. I know this for sure because when the car is cold soaked, the cabin heater takes about 6 kW. Once the drive train has warmed up by highway driving the cabin heater power consumption drops down to about 1 to 1.5 kW, even in very cold conditions. In comparison the cabin heater for the tiny cabin in the Roadster takes far more energy. Clearly they're using the heat pump to heat the cabin, using the motor coolant loop as the reservoir. (Yes there are indications they don't use the battery coolant loop - in extreme cold the battery never really gets properly warm during highway driving - too much exposed area underneath.)

It's one of the reasons why driving the Model S in winter is MUCH more comfortable than driving the Roadster - you can keep the heat on!!!

As for doing that on the race track, it probably makes no difference whatsoever. I believe the main reason that the motor gets too hot too quickly is that it's hard to remove the heat from the rotor.

nwdiver · Dec 13, 2014

When I was traveling through Oregon last winter I had the AC set to 'eco'. The car got noticeably warmer going up-hill vs downhill... I thought that was amusing...

However... I'm pretty sure that running the heater 'full blast' will just increase the drain on the battery... I think the car is more than capable of cooling itself so sending more heat to the cabin is probably negligible.

Nuke · Dec 15, 2014

You guys also have the issue that 2 full power pickups is the max to get the limiter to kick in

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Delay Power Limiting By Running The Heater?

ratsbew

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ecarfan

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pgiralt

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freds

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Doug_G

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nwdiver

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Nuke

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