I have a 22 M3LR with heat pump. This weekend, I took a roadtrip in some of the most extreme cold ever. The trip started at -31C (-23.8F) and temps dropped through the day to -35C (-31F). The cabin was set to 20C (68F). When the car started to precondition for supercharging (about 100km, 62 miles), the heat for the cabin completely shut off. Thank god for heated seats and heated steering wheel! Heat did not return until I started supercharging. Has anyone ever experienced this? I'm guessing the car was redirecting the heat to warm up the battery?
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Preconditioning to supercharge in extreme cold turns off cabin heating
- Thread starter Sypher
- Start date
fiehlsport
Tire Guy
It makes sense to me.
On the early Model Y, people supercharging in the desert would lose cabin AC because the heatpump would divert cooling to the battery. It was to the point where the battery was dangerously hot, and not using 100% cooling capacity could cause damage to it. I think the cooling strategy has changed since 2020, but it's definitely the car doing a form of self-preservation when this occurs.
Without turning the cabin heat off, the battery would be a brick of ice, and would not accept any charge at all. I think in this case, as long as you've got heated seats and wheel, you're better off letting the car do its thing so you can guarantee it will start charging so you have a usable vehicle that drives. The battery will not accept a charge at all when it is that cold, so you'd effectively be stuck for longer in the cold if the car was heating the cabin too. (With what limited heat there is in the outside air for the heat pump to pull from)
See this video: The car takes a long time before it will even start charging when it's very cold out.
On the early Model Y, people supercharging in the desert would lose cabin AC because the heatpump would divert cooling to the battery. It was to the point where the battery was dangerously hot, and not using 100% cooling capacity could cause damage to it. I think the cooling strategy has changed since 2020, but it's definitely the car doing a form of self-preservation when this occurs.
Without turning the cabin heat off, the battery would be a brick of ice, and would not accept any charge at all. I think in this case, as long as you've got heated seats and wheel, you're better off letting the car do its thing so you can guarantee it will start charging so you have a usable vehicle that drives. The battery will not accept a charge at all when it is that cold, so you'd effectively be stuck for longer in the cold if the car was heating the cabin too. (With what limited heat there is in the outside air for the heat pump to pull from)
See this video: The car takes a long time before it will even start charging when it's very cold out.
What I don't understand is that on my non-heatpump 2020 model, the motors are used to heat the battery and the resistive heater for the cabin. Since the SC can provide enough energy for both draws, I suspect both would work fine. I know heatpump car can blend both systems but they should still be generating heat from the motors, not worse than my 2020. I understand that adding the power of the heatpump for the battery will make it go faster, but that's to the expense of human comfort and to a certain point could be dangerous when it's very cold. It would be so easy to just make that optional: turn off cabin heating and the car then uses it for the battery. The "switch" is already there. Why force it though, I don't understand.
fiehlsport
Tire Guy
That's a good point - the older cars just used the motors to generate battery heat, which the heatpump cars can still do. I assume there is a mode where it can use motors only, heat pump only, or both using the magic of the Octovalve.
It's probably possible to make a heatpump car work in the old-school method of just waste heat from the motors. Why Tesla doesn't is another question...
I wouldn't be surprised if both the motors and heat pumps were used to get the batteries heated. It was absolutely freezing that day and without the help of both heating systems, it likely wouldn't have got the battery warm enough to supercharge at a decent rate. I found it interesting that I haven't heard of this ever happening with anyone else. I don't think that Tesla Bjorn made any mention of this on his Model 3 long range arctic circle run video despite driving through similar conditions.
I agree as well. There is a balance needed between user comfort/safety and battery comfort/safety. In the case where the battery is getting too hot or too cold I would say it is ok to take away from the cabin IF and only if the danger to the battery could cause a catastrophic safety of life failure(battery catches fire). Other than that it should never by default take away from the cabin comfort settings without the user explicitly agreeing.
I havent seen any example of heat turned of during preheating of the battery with my '21 heat pump M3P.
I have a lot of supercharging sessions in cold WX. I have experienced a slight variation in the cabin heating, like it is periodically lowering a few degrees but no complete "heating shut down".
I would guess its time to go to the service center if the heatpump does not deliver heat when preheating.
I have a lot of supercharging sessions in cold WX. I have experienced a slight variation in the cabin heating, like it is periodically lowering a few degrees but no complete "heating shut down".
I would guess its time to go to the service center if the heatpump does not deliver heat when preheating.
At extreme temps, odd things do happen. I'd let the SC know just in case it's something that a future software update can address.
I carry a little heatable blanket that uses the 12V plug, just in case, so with heated seats and the heatable blanket, I'm set.
I suppose, if it got too cold inside, since you had to drive 100km, you could turn off the nav to supercharger, then the precondition would turn off, and you could get some heat, then when warm, you could turn nav back on, so the car could precondition. Ultimately, at the supercharger, the battery would continue heating before charging, if the pack was still too cold. So, it would only cost you a bit of time, and possibly some future battery deg.
I had the heat pump stop when the car was about one week. It stopped heating when I left the garage for a 250 km winter drive.
Some -11C outside so not extremely cold.
I decided to stop at the Supercharger that was on nu the way after 50km, nav to precindition + charged back to 100%.
When leaving the supercharger, after deciding not to go home and change to the fossile car, it was a 200 km drive without heating.
There was a need to have the fan running to keep the windscreen non foggy/frosty.
There was a clear component of heating trough the floor. The feet was less cold if put flat to the floor.
Having never contacted Tesla before, do I do this through the app via a service request? Not sure if the service center can even replicate this incident as it's no longer frigid.
I have experience in generally similar conditions to yours - but without symptoms as extreme as what you noticed. I have a 2022 M3P - a couple weeks ago took it on a roughly 1700km round trip in 2 days. Day 2 was driving through the night about 800km in roughly -28 C to -34 C. Average driving speed roughly 125km/hr, and preconditioning between superchargers generally took an hour or so before estimated arrival. On a couple occasions (especially on a longer stint where the car hadn't been preconditioning or supercharging for an hour (gaps of ~200-250km between charges), then kicked on preconditioning), the cabin heat was reduced temporarily. At no point did the cabin heating shut off outright, but there was a noticeable drop in temperature for a short bit before it "caught back up" and returned to blowing warm air.
I believe your car might have some fault in the hvac/heat pump hardware or software if it completely turned off on the highway while preconditioning, and absolutely would schedule an appointment. I would suggest providing details to them about the time & location of the drives when it happened so they can look into those times specifically. Good luck!
I believe your car might have some fault in the hvac/heat pump hardware or software if it completely turned off on the highway while preconditioning, and absolutely would schedule an appointment. I would suggest providing details to them about the time & location of the drives when it happened so they can look into those times specifically. Good luck!
So I ended up booking a service giving them details of what happened. I didn't think that they would be able to really do anything about it since it would be hard to replicate given that we haven't had another cold snap as bad as that weekend.
Turns out they were able to remotely diagnose the car and suspected there is a problem with the heat pump and possibly other HVAC parts. They ordered the parts in ahead of my appointment with them. Upon physical inspection, they ended up replacing the heat pump, supermanifold, lines connecting the supermanifold to the heat pump, and active grill shutters. Hopefully that resolves the issues.
