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Heating enery use

jcanoe

Well-Known Member
Oct 2, 2020
6,814
7,715
Maryland
The seat heater(s), steering wheel heater (where equipped), rear window defroster are all 12V systems. The power used by these accessories, even if all of them are set to high at the same time is something under 1kW, probably closer to 500W. The Model Y can draw up to 7kW power to warm the battery pack and the cabin via the front and rear motor stators. In addition the heat pump can draw additional power for a total of ~12kW when usng maximum defrost setting. For driving once the battery has been warmed, probably ~3kW to 6kW. So without exact measurements the cabin heating can be expected to use 10X the power of the seat heaters and other 12V accessories.

One strategy for conserving the energy stored in the battery pack to maximize range is to precondition the Model Y while still plugged in. In cold weather precondition for at least 30 minutes.Turn on the seat heaters to high and the steering wheel heater on while preconditioning. As you leave turn the seat heaters to low or medium as the seat will be comfortable warm. Set the HVAC temperature to ~68F to 70F; don't turn off the HVAC else the windows will likely start to fog up on the inside. Dress warmly; wear gloves and a hat and you won't need as much cabin heat. Drive 5 to 10 MPH slower than you usually would drive on the highway as this will yield lower Wh/mi consumption and greatly extend your driving range much more than minimal use of the HVAC settings.
 
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A crap ton - I lost about 20 miles of range bringing the car up to 70s and heating the battery pack the other day. Granted it was -5F out. That plays a huge part in that energy draw as the heat pump will start out at 100% duty cycle until it starts getting warm in the vehicle and then ramp down. So when it's +25F out, it runs at a lower duty cycle - and I can hear that difference. The flip side was that today I didn't do a 15-30 minute pre-condition and I had limited power and regen. I had a blue section of my battery when I turned it on, I did wait until it went away before driving off, but a lot of that was the windshield wipers were frozen in place (first vehicle to ever have done that to me) and the windshield itself was fogged up. Limited power wasn't noticeable for the entire drive as I rarely (basically never) floor it. But I had no regen and that in and of itself took out more energy then letting it precondition. (400-500 wh/mi vs 716 wh/mi today)...
 
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scabbotts

Member
Supporting Member
Jan 4, 2021
34
22
Maine
The seat heater(s), steering wheel heater (where equipped), rear window defroster are all 12V systems. The power used by these accessories, even if all of them are set to high at the same time is something under 1kW, probably closer to 500W. The Model Y can draw up to 7kW power to warm the battery pack and the cabin via the front and rear motor stators. In addition the heat pump can draw additional power for a total of ~12kW when usng maximum defrost setting. For driving once the battery has been warmed, probably ~3kW to 6kW. So without exact measurements the cabin heating can be expected to use 10X the power of the seat heaters and other 12V accessories.

One strategy for conserving the energy stored in the battery pack to maximize range is to precondition the Model Y while still plugged in. In cold weather precondition for at least 30 minutes.Turn on the seat heaters to high and the steering wheel heater on while preconditioning. As you leave turn the seat heaters to low or medium as the seat will be comfortable warm. Set the HVAC temperature to ~68F to 70F; don't turn off the HVAC else the windows will likely start to fog up on the inside. Dress warmly; wear gloves and a hat and you won't need as much cabin heat. Drive 5 to 10 MPH slower than you usually would drive on the highway as this will yield lower Wh/mi consumption and greatly extend your driving range much more than minimal use of the HVAC settings.
Wow, great information, thank you. I knew somebody out there would know the specifics on the energy usage.
 

pt19713

Active Member
Feb 5, 2020
1,062
1,394
Delaware
Seat and steering wheel heaters draw on the order of something like 50 watts each. So much less costly than full cabin heating - heat pump or not.
Yeah, heated seats use 100 watts (per seat) versus 500-1000 watts at moderate temperature and can speeds. It can pull 1.5-3 kW or higher if you set the defrost to HI. Rear defrost tagged about 200 watts. I don't know about the heated steering wheel since mine doesn't have it.

All info is from the Scan My Tesla app.
 
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