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Tesla Space Heater?

timx

Member
Jan 12, 2017
52
49
Iowa
So the temperature has been around -20F for most of the last few days, and our Tesla X100D is parked in an attached garage with pipes in the ceiling overhead that have had issues freezing in the past.

On Sunday night around 10pm, with the garage temperature approaching freezing, we rolled down the windows of the X, opened all doors, and turned on the cabin heat (front and back) at full blast on MAX temperature, and charged the battery from 80-90% (to get some heat going faster). Then we forgot about it and fell asleep.

Around 4am I woke up sweating, went down to the garage which the Tesla reported as 109F inside the cabin (and it certainly felt like that throughout the garage), and noticed what appeared to be the battery _cooling_ system running at full blast (the loudest I've ever heard it). I turned off the cabin heat on the Tesla and opened the door to the house to dissipate the heat, and the battery cooling system kept going, then eventually came to a stop over the next half hour.

It would appear that the temperature in the garage as a result of cabin heating exceeded a certain limit causing the battery cooling system to kick in, and resulted in a thermal runaway condition (for the car at least, though perhaps eventually limited by heat dissipated out of the garage). While 109F would appear to be below anything dangerous, I would think it can't be good for the battery long-term. Though it certainly makes for a great space heater!

Does anyone know if the software would detect such condition and stop the heating and/or battery conditioning after reaching a certain limit? Or is using a Tesla as a space heater a bad idea all around?
 

mongo

Well-Known Member
May 3, 2017
13,809
44,332
Michigan
So the temperature has been around -20F for most of the last few days, and our Tesla X100D is parked in an attached garage with pipes in the ceiling overhead that have had issues freezing in the past.

On Sunday night around 10pm, with the garage temperature approaching freezing, we rolled down the windows of the X, opened all doors, and turned on the cabin heat (front and back) at full blast on MAX temperature, and charged the battery from 80-90% (to get some heat going faster). Then we forgot about it and fell asleep.

Around 4am I woke up sweating, went down to the garage which the Tesla reported as 109F inside the cabin (and it certainly felt like that throughout the garage), and noticed what appeared to be the battery _cooling_ system running at full blast (the loudest I've ever heard it). I turned off the cabin heat on the Tesla and opened the door to the house to dissipate the heat, and the battery cooling system kept going, then eventually came to a stop over the next half hour.

It would appear that the temperature in the garage as a result of cabin heating exceeded a certain limit causing the battery cooling system to kick in, and resulted in a thermal runaway condition (for the car at least, though perhaps eventually limited by heat dissipated out of the garage). While 109F would appear to be below anything dangerous, I would think it can't be good for the battery long-term. Though it certainly makes for a great space heater!

Does anyone know if the software would detect such condition and stop the heating and/or battery conditioning after reaching a certain limit? Or is using a Tesla as a space heater a bad idea all around?

No worries, the vehicle can operate in 109F conditions. The battery itself was below the cabin temp due to the air conditioner running to cool the pack. If the pack temp had gotten too high, I expect the vehicle would throw a fault and disable operation.

Edit: From the manual
Do not expose Model X to ambient
temperatures above 140° F (60° C) or
below -22° F (-30° C) for more than 24
hours at a time.
 
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Tdreamer

Plaid Supercharger
Supporting Member
Sep 10, 2017
1,390
2,755
Bedford, Massachusetts
I used my X to heat our garage this past month a few times while doing some work out there. Very convenient. Sound system helped the work go faster as well :)
 
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arcus

Active Member
Aug 11, 2017
1,303
968
Denton, TX
No worries, the vehicle can operate in 109F conditions
We know something about it down here :D

On a similar note, I left the car charge setting at 100% accidentally after the last visit to SC. It charged overnight to 100%, but I didn't have any need to run errands on that day and was concerned about leaving the battery at full charge for too long. Recalling similar thread, I just cranked up the heat for 30 mins to get below 90% charge. Just with front windows partially rolled down the garage was 5 degrees warmer afterwards.
 
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timx

Member
Jan 12, 2017
52
49
Iowa
I've tried using mine as a space heater, but it didn't help much. Maybe I didn't have it turned up high enough?
The cabin heater alone seemed to help somewhat, though it seems getting the battery cooling in a runaway loop is what caused rapid increase in temperature (the more heat ejected from the car, the hotter it gets, and the cooling mechanism runs harder and harder in a positive feedback loop). I suppose this would require the garage to have sufficient insulation and small enough space to minimize dissipation of heat. In my case, 24 ft x 20 ft x 8 ft high, two walls exterior, all surfaces insulated.
 

mongo

Well-Known Member
May 3, 2017
13,809
44,332
Michigan
The cabin heater alone seemed to help somewhat, though it seems getting the battery cooling in a runaway loop is what caused rapid increase in temperature (the more heat ejected from the car, the hotter it gets, and the cooling mechanism runs harder and harder in a positive feedback loop). I suppose this would require the garage to have sufficient insulation and small enough space to minimize dissipation of heat. In my case, 24 ft x 20 ft x 8 ft high, two walls exterior, all surfaces insulated.

With everything in the same space, the addition of the battery cooling added the energy used to run the compressor, pumps, and cooling fans to the overall heat load. There was an additional rise to the room temp due to the shift in thermal energy away from the pack.

For grins, I ran some numbers. Your garage is about 108 m^3 so takes 133 kJ to raise the temp one degree C. 109 F from 32 F is about 43 C so 5,700kJ or so total (ignoring losses and vehicle thermal mass). If the pack weighs 600 kg and is (totally made up numbers that are too small) 15% steel, 15% aluminum, 15% lithium then the specific heat of the pack is 441 kJ/kg per degree C. That results in a temp shift of 13 degrees C in the pack to heat the room the 43 degrees C.
Of course, the pack didn't go below freezing, but it shows the kind of magnitude difference (4:1) between the thermal energy of the pack and the environment.
 

Saghost

Well-Known Member
Oct 9, 2013
8,224
7,086
Delaware
I don't think the car is smart enough to realize that it is trapped in a small space with the doors/windows open and therefore it is the source of the heat that's causing it to engage in battery cooling.

I don't think Max will allow the heater to run to dangerously high temperatures, and I don't think the car will allow the battery to reach dangerous temperatures in your scenario.

I'm not certain how the cooling capability of the battery chiller compares with the heating capability of the cabin heater - from the few numbers I've seen I suspect the battery chiller has more total power, though if it and the cabin heat are dumping heat into a perfectly insulated environment, it'll eventually heat up to the point that the difference doesn't matter.
 
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SabrToothSqrl

Active Member
Dec 5, 2014
3,844
3,246
PA
lol that's funny. i never thought about using my car as a space heater. I do however dislike how when you turn the HVAC on via the app, it STAYS ON FOREVER. I greatly preferred the 30 min time out.
 

CinRedMan

Member
Aug 28, 2017
111
72
Dayton, Ohio
I really appreciate this post/thread as I have been pondering the possibility of using my MS to provide heat in my garage, but had yet to actually take any action. Especially after the SW update which includes "keep climate on"
 

Saghost

Well-Known Member
Oct 9, 2013
8,224
7,086
Delaware
I really appreciate this post/thread as I have been pondering the possibility of using my MS to provide heat in my garage, but had yet to actually take any action. Especially after the SW update which includes "keep climate on"

As long as you don't set it to "Max" I don't think there's any risk - although you'll certainly see it in your electric bill if you do much of it.
 

Tslacg

Member
Apr 5, 2016
200
114
Oklahoma city
I've used mine as a space heater a few times in a storage unit working on my expedition rv. When it's below freezing in the storage unit I set the temp to max and camping mode on fan 4. Use outside air and it'll exchange air over a few times pretty quickly. Windows down or cracked and run it for 15ish minutes.

Propane heater works a lot quicker, but it's useful in a pinch or if it's not worth firing up the propane heater. I usually only lose 1RM every half hour
 

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