Heating system Model S

[dspwhite]

Wattage and immediacy of interior heating for comfort

Petrol drive cars often take a time to heat up the inside - as long as 20 minutes, and maybe 5 mins for modern cars today.

However, seeing as the Tesla S is electric, is the air instantly warm as soon as you switch it on?

Also, what's the maximum wattage of the internal heating system? For comparison, my convector heater in my house is 2kW, so I hope it's close to that.

 

[youlikeadajuice]

Does anyone know approximately how much more efficient it is to use the heated seats vs. only the cabin heat in the Model S? I'd rather go with the textile interior, but don't want to take a huge hit on mileage by running the cabin heat, so leather may be necessary. From reading different posts, it's obvious that it's more efficient to use the heated seats, but are we talking a little or a lot? Sorry if this has already been answered, couldn't find the answer I was looking for, thanks!

 

[steve841]

It's been suggested that heated seat use is preferred to using the HVAC for heating..

Limit the use of resources such as heating and air conditioning. Using
seat heaters to keep warm is more efficient than heating the cabin.

 

[Joel]

I've had my Model S for three weeks and temperatures in Michigan ranged from 30 Degrees Fahrenheit (Freezing) to 60 Degrees Fahrenheit. From my experience:

1) When temperatures were at or just below freezing, using the HVAC (without seat warmers), the Model S warmed up to 70 Degrees Fahrenheit (cabin temperature) in approximately 2 minutes (or less).
2) Keeping the cabin at 70 Degrees did not significantly reduce range. I drove 70 MPH on the highway with the outside temp at 34 Degrees Fahrenheit and the cabin temperature at 70 Degrees Fahrenheit. I drove 120 miles (all highway). My Watts Per Mile was 315 (270 Miles of range).
3) While warming the cabin has a minimal reduction on range, I noticed that warming the battery does require a lot of juice. In other words, at temperatures of 32 degrees Fahrenheit or below, the first few miles of driving at city speeds (30 MPH to 40 MPH) translated into something like 480 to 520 Watts Per Mile. However, after 2 to 4 miles of driving, the battery did warm up to its optimal temperature and my WPM dropped to something like the low 300s.

I hope this helps.

 

[youlikeadajuice]

I've had my Model S for three weeks and temperatures in Michigan ranged from 30 Degrees Fahrenheit (Freezing) to 60 Degrees Fahrenheit. From my experience:

1) When temperatures were at or just below freezing, using the HVAC (without seat warmers), the Model S warmed up to 70 Degrees Fahrenheit (cabin temperature) in approximately 2 minutes (or less).
2) Keeping the cabin at 70 Degrees did not significantly reduce range. I drove 70 MPH on the highway with the outside temp at 34 Degrees Fahrenheit and the cabin temperature at 70 Degrees Fahrenheit. I drove 120 miles (all highway). My Watts Per Mile was 315 (270 Miles of range).
3) While warming the cabin has a minimal reduction on range, I noticed that warming the battery does does require a lot of juice. In other words, at temperatures of 32 degrees Fahrenheit or below, the first few miles of driving at city speeds (30 MPH to 40 MPH) translated into something like 480 to 520 Watts Per Mile. However, after 2 to 4 miles of driving, the battery did warm up to its optimal temperature and my WPM dropped to something like the low 300s.

I hope this helps.

Thanks, this info is very helpful and definitely answers my question. I appreciate the help!

 

[cinergi]

The seat heaters use, for all practical purposes, no power. Cabin heating uses a *TON* of power -- but what I haven't seen anyone talk about yet is what it's like to keep the cabin at 70F when it's 0F outside. The cabin seems to be ridiculously-well insulated. I'm surprised at how little energy is required to keep it at 70 inside when it's 40 outside. You can almost get away with shutting the heat off once the cabin's comfortable inside when it's 45 outside.
It also takes a relatively short burst of energy to get the cabin up to operating temperature if it's been sitting in the cold. Again -- no known observations from 0F. To me, that's the real test. These 40F days just don't count :smile:

I find I'm able to turn the heat down if I have the seat heaters on -- so yes, it helps. I'm just not sure if being able to lower the cabin temp by several degrees will make a significant impact. But I can tell you I'm more comfortable having the seat warmers on and cabin at 73 than I am with them off and cabin at 77 (73/77 is high -- I think my interior sensor has issues or something .. it's not REALLY 73/77 inside).

 

[widodh]

So we want that iPhone/Android App really quickly so we can turn on the cabin heater while the car is still connected to the grid so we can draw power from there instead of the battery.

Saves you some range again

 

[harry]

I have no idea about the wattage, but the heat is not so quick. Mine blows cold air for a couple of minutes. It would seem that the blower could be held back until the heat was distributed in the system. I'm assuming they are using a scroll compressor as a heat pump, but that's just a guess.

 

[dspwhite]

Thanks, that's unfortunate. One of the big advantages of an electric car, is that any standard electric appliance can theoretically be used. When I put on my convector fan heater, heat instantly comes out. And so it should be the same with the Model S or any electric car.

I'm guessing that the 'waste' heat is used to supply the interior heating, but this should be at least supplemented by the battery's direct power.

 

[GSP]

In my Volt the seat heaters use about 50W each, vs about 5000W for the cabin heater. Seat heaters allow me to keep the cabin heater off most of the time, or use a lower setting when it is needed. Seat heaters for all seats should be standard on all EVs.

GSP

PS. The Volt can be set up to turn the seat heaters on when pre-conditioning the cabin (GM calls this "remote start"). I hope Tesla will offer this also.

 

[Robert.Boston]

I agree it's surprising, but it won't matter much: just use the smartphone app to preheat the car.

 

[darthy001]

In my Volt the seat heaters use about 50W each, vs about 5000W for the cabin heater. Seat heaters allow me to keep the cabin heater off most of the time, or use a lower setting when it is needed. Seat heaters for all seats should be standard on all EVs.

GSP

PS. The Volt can be set up to turn the seat heaters on when pre-conditioning the cabin (GM calls this "remote start"). I hope Tesla will offer this also.

5000w is it really that much?

Just comparing to an electric heater at home which can heat a livingroom on only 1500w...

Personally i'm not a fan of seatheating so this could be an issue for me. My wife refuses to use it even In the coldest of conditions as well...

 

[Robert.Boston]

In my Volt the seat heaters use about 50W each, vs about 5000W for the cabin heater. Seat heaters allow me to keep the cabin heater off most of the time, or use a lower setting when it is needed. Seat heaters for all seats should be standard on all EVs.

PS. The Volt can be set up to turn the seat heaters on when pre-conditioning the cabin (GM calls this "remote start"). I hope Tesla will offer this also.

My son really loves heated seats, so it's a shame that the rear seats in the Model S aren't heated. That would be a nice upgrade to have available.

+1 on the idea of activating the seat heat through the smartphone app. The great thing with the MS is that, because there are no buttons, the software has access to nearly everything.

 

[jerry33]

5000w is it really that much?

That's probably the maximum amount assuming a variable speed scroll compressor heat pump. The difference between your house and the car is that in the house it's maintaining temperature rather than bringing it up from ambient. The Prius' A/C has been measured at over 3 kW (but mostly it runs far lower), so 5 kW is in the ballpark for a maximum on a larger car.

A hair dryer is 1500 W so you can imagine about how long a hair dryer would take to warm up the car.

 

[GSP]

5000w is it really that much?
..

I think so, but I have not measured it myself. I have seen the 5kW number a few times, but not directly from GM. It is a resistive heater, not a heat pump.

GSP

 

[cinergi]

The Roadster with its tiny cabin uses over 3kW for heat. And that was insufficient. Increasing the cabin temperature (and air ducts, interior components, etc -- all the cold-soaked stuff) of a car from -10F or worse to 70F requires a serious heating system.

 

[Brian H]

The Roadster with its tiny cabin uses over 3kW for heat. And that was insufficient. Increasing the cabin temperature (and air ducts, interior components, etc -- all the cold-soaked stuff) of a car from -10F or worse to 70F requires a serious heating system.

Did you see the Roadster hint? Block the passenger vent. Warms the driver side much better, but doesn't much affect the passenger's comfort.

 

[Doug_G]

The Roadster with its tiny cabin uses over 3kW for heat. And that was insufficient. Increasing the cabin temperature (and air ducts, interior components, etc -- all the cold-soaked stuff) of a car from -10F or worse to 70F requires a serious heating system.

That is true, but the Roadster isn't exactly "sealed" - you get a lot of cold air coming in. If I'm trying to hypermile in winter I turn off the heat, put it on recirculate, set the air flow to the vents, close all the vents (effectively a "no air" setting), and turn on the seat heater. Even so you do get some cold air coming in.

A heat pump should be much more efficient, especially if they can use the battery itself as a thermal reservoir.

 

[cinergi]

Did you see the Roadster hint? Block the passenger vent. Warms the driver side much better, but doesn't much affect the passenger's comfort.

Yup. I also preheated when I could so the ducts and items in the car would get warm and stop acting like ice blocks. Then the heater only had to overcome poor insulation and air leaks.

- - - Updated - - -

That is true, but the Roadster isn't exactly "sealed" - you get a lot of cold air coming in. If I'm trying to hypermile in winter I turn off the heat, put it on recirculate, set the air flow to the vents, close all the vents (effectively a "no air" setting), and turn on the seat heater. Even so you do get some cold air coming in.

A heat pump should be much more efficient, especially if they can use the battery itself as a thermal reservoir.

Yup like I said above the model s is ridiculously well insulated and has no discernible air leaks so I almost don't need the heat even at 45F. Combined with the heat pump it'll be much more efficient but you have way more cabin space to deal with. The system needs to be powerful enough to quickly overcome cold-soak from sitting in -10F temps. I'll have to crank the heat some time and watch the power meter and estimate the draw. It's quite significant from what I remember.

 

[mknox]

That is true, but the Roadster isn't exactly "sealed" - you get a lot of cold air coming in. If I'm trying to hypermile in winter I turn off the heat, put it on recirculate, set the air flow to the vents, close all the vents (effectively a "no air" setting), and turn on the seat heater. Even so you do get some cold air coming in.

How did that affect window fogging? I've always found that unless I keep heated air flowing and avoid the re-circ function, I'll get terrible fogging on all windows. Sometimes, even in cool, damp conditions I have to keep the a/c compressor running to avoid window fogging.