Which consumes more power?

[Mateo83]

The heating system or the heated seats and wheel?

I was thinking about this while driving, and my round-trip estimate was a single-digit battery percentage when I got home. When its 40 degrees or less outside, Could you turn off the heater and still use the heated seats to conserve some battery? or vice versa.

 

[brkaus]

Heated seats and wheel take less than the climate system.

Best bet if your running short is to slow down.

 

[OxBrew]

I've seen the SOC prediction bump up 3-5% after dropping the climate 5°F and turning the heated seats down 1 bacon, with IDK, 150-200 miles to go, below freezing outside.

 

[LoudMusic]

I don't know how much power the seats and wheel heating systems consume, but electric blankets are usually less than 200w "per person" - so maybe 400w for a queen or king size. That's a huge amount of area compared to a wheel or seat. I bet those are sub 100w each. The heater, even if it's a heat pump, is probably between 500 and 1000 w.

But really, if you look at how much the vehicle consumes pushing the car down the road, the HVAC is a tiny portion. When I drive 75mph my car gets about 310wh/mi. So that's 23,2500w versus the HVAC doing 1000w? Or 1000w (HVAC consumption) would be about 3 miles of range if you were getting 333wh/mi.

I don't even think about it anymore. Turning it off won't recoup enough. Just slow down if you're worried. That's the big energy savings.

 

[TomB985]

I don't know how much power the seats and wheel heating systems consume, but electric blankets are usually less than 200w "per person" - so maybe 400w for a queen or king size. That's a huge amount of area compared to a wheel or seat. I bet those are sub 100w each. The heater, even if it's a heat pump, is probably between 500 and 1000 w.

But really, if you look at how much the vehicle consumes pushing the car down the road, the HVAC is a tiny portion. When I drive 75mph my car gets about 310wh/mi. So that's 23,2500w versus the HVAC doing 1000w? Or 1000w (HVAC consumption) would be about 3 miles of range if you were getting 333wh/mi.

I don't even think about it anymore. Turning it off won't recoup enough. Just slow down if you're worried. That's the big energy savings.

I haven't tracked this system with an OBD reader, but I spent a fair amount of time logging data on my EV6. That car would burn about 1 kW for every thousand RPMs of compressor speed. The faster the compressor spun, the more power it took. The EV6's heat pump would turn around 3,000 RPMs at most when heating the cabin, and it supplemented that with a PTC heater. So between 2.5-3.5 kW in colder weather.

The Model Y doesn't have a PTC heater, and the compressor seems to be much more powerful. It spins as much as 9,000 RPMs. I know it takes less than 9 kW, but I'm certain that it's more than 1,000w. The electric compressor in a Prius can draw as much as 4.5 kW.

 

[jcanoe]

No contest; the heated seats and steering wheel use ~1/10th the power that the climate control and heat pump can consume. The entire low voltage system is limited to under 2kW (heated seats, heated steering wheel, lights, wipers, audio, power windows and seats, blower motor, rear defogger/defroster). The Climate Control system can draw upwards of 8kW (even up to 15 kW if the motor stators are being used to warm the battery.)

 

[LoudMusic]

That's WAY more than I anticipated. My HVAC on my boat was 120v12a max and heater or cooled quite a large space. But it was also using seawater to dump heat. Still seems excessive for the car.

 

[jcanoe]

That's WAY more than I anticipated. My HVAC on my boat was 120v12a max and heater or cooled quite a large space. But it was also using seawater to dump heat. Still seems excessive for the car.

The Climate Control heat pump is a 360V, variable speed, liquid cooled unit. The heat pump is at least twice as efficient as the PTC (resistance) heating unit used in the original Model 3 but it can consume quite a bit of power, especially when you first start preconditioning or driving. Once the passenger cabin is warmed (or cooled) to the desired temperature the climate control will use less power. Based on how much slower my Model Y charges at Level 2 at a ~6kW charging rate (200V and 30 amps) when the climate control is running versus just charging I estimate ~2kW to 3kW to maintain a comfortable cabin temperature.

 

[TomB985]

The Climate Control heat pump is a 360V, variable speed, liquid cooled unit. The heat pump is at least twice as efficient as the PTC (resistance) heating unit used in the original Model 3 but it can consume quite a bit of power, especially when you first start preconditioning or driving. Once the passenger cabin is warmed (or cooled) to the desired temperature the climate control will use less power. Based on how much slower my Model Y charges at Level 2 at a ~6kW charging rate (200V and 30 amps) when the climate control is running versus just charging I estimate ~2kW to 3kW to maintain a comfortable cabin temperature.

I agree with most of that, but it’s not liquid cooled. There is a coolant line bracket that you need to remove when you replace the compressor, but there is no plumbing from the cooling system that goes into the compressor.

I did some digging around and found THIS ARTICLE which suggests a 5-6 kW max consumption with the heat pump. I stopped procrastinating and ordered an OBD pigtail, so I’ll measure HVAC draw when it arrives. I did this with my Model 3 and saw a 5 kW max draw, but the heat pump in my Y seems to throw a lot more heat.

 

[Mateo83]

I haven't tracked this system with an OBD reader, but I spent a fair amount of time logging data on my EV6. That car would burn about 1 kW for every thousand RPMs of compressor speed. The faster the compressor spun, the more power it took. The EV6's heat pump would turn around 3,000 RPMs at most when heating the cabin, and it supplemented that with a PTC heater. So between 2.5-3.5 kW in colder weather.

The Model Y doesn't have a PTC heater, and the compressor seems to be much more powerful. It spins as much as 9,000 RPMs. I know it takes less than 9 kW, but I'm certain that it's more than 1,000w. The electric compressor in a Prius can draw as much as 4.5 kW.

View attachment 908036

Very interesting.

 

[SageBrush]

But really, if you look at how much the vehicle consumes pushing the car down the road, the HVAC is a tiny portion.

Cabin heating can be up to ~ 5 kW, while moving down the road is about 20 kW at ~ 65 mph.

Definitely use wheel and seat heating where possible to reduce or eliminate cabin heating

 

[Mateo83]

Cabin heating can be up to ~ 5 kW, while moving down the road is about 20 kW at ~ 65 mph.

Definitely use wheel and seat heating where possible to reduce or eliminate cabin heating

My only complaint is when the heating system is off. The damn windows fog up.

 

[SageBrush]

My only complaint is when the heating system is off. The damn windows fog up.

It took me a while to understand foggy windows, and how to avoid them. E.g., my winter climate is cold but low humidity, so my approach is to not add humidity to my cabin air by things like hot beverages in the car, and to swap in just enough outside air to stay above dew point.

In climates that have higher humidity, the approach will vary. It might mean dehumidifying the cabin air and keeping ventilation to a healthy minimum, or it could mean selective heating of the glass. It always means not bringing hot beverages into the vehicle in the winter.

Find the lowest energy way to keep the glass clear, and then if you or your passengers are cold, heat them up with localized methods like heat seating. Did I mention not bringing hot beverages into the car ?

 

[LoudMusic]

I don't know where y'all are getting your numbers from but I have a hard time believing the HVAC on these cars can draw more than 2kw.

This article suggests numbers more online with what I had suggested.

A comparison of a Tesla Model 3 with a heat pump to one without shows impressive results

We compare a newer Model 3 that has a heat pump with an older one that doesn't, and the former shows impressive results.

electrek.co

 

[ItsNotAboutTheMoney]

It took me a while to understand foggy windows, and how to avoid them. E.g., my winter climate is cold but low humidity, so my approach is to not add humidity to my cabin air by things like hot beverages in the car, and to swap in just enough outside air to stay above dew point.

In climates that have higher humidity, the approach will vary. It might mean dehumidifying the cabin air and keeping ventilation to a healthy minimum, or it could mean selective heating of the glass. It always means not bringing hot beverages into the vehicle in the winter.

Find the lowest energy way to keep the glass clear, and then if you or your passengers are cold, heat them up with localized methods like heat seating. Did I mention not bringing hot beverages into the car ?

Corollary: when you pick up pizzas, be prepared to blast defog.

 

[SageBrush]

I don't know where y'all are getting your numbers from but I have a hard time believing the HVAC on these cars can draw more than 2kw.

In steady state, meaning the cabin has reached the thermostat temperature, and now the heat pump just has to keep the cabin at that temperature.

 

[SageBrush]

Corollary: when you pick up pizzas, be prepared to blast defog.

Corollary of your corollary: The more you blast the windows, the worse the pizza tastes

 

[rwiegand]

For efficiency sake I wish I didn't hate having a hot butt so much. I'm condemned to the occasional extra charging stop.

 

[CapsEngineer]

It took me a while to understand foggy windows, and how to avoid them. E.g., my winter climate is cold but low humidity, so my approach is to not add humidity to my cabin air by things like hot beverages in the car, and to swap in just enough outside air to stay above dew point.

In climates that have higher humidity, the approach will vary. It might mean dehumidifying the cabin air and keeping ventilation to a healthy minimum, or it could mean selective heating of the glass. It always means not bringing hot beverages into the vehicle in the winter.

Find the lowest energy way to keep the glass clear, and then if you or your passengers are cold, heat them up with localized methods like heat seating. Did I mention not bringing hot beverages into the car ?

You forgot to add not breathing.

 

[SageBrush]

You forgot to add not breathing.

3a. Apologize to the panting doggy for leaving it at home