Heating system Model S

[Milzit]

Hello
I´m living in Norway and we are considering to make a reservation for Model S. Do anybody have any information about the heating system or is that not ready yet? In a country like Norway you need heating in the winter.. It will just take the power from the battery?

[EV_de]

it's part of the Model-S-feature-wishlist.

together with remote controlled (pre) heating / cooling

[Cobos]

The Roadster uses electric heating and not a heatpump. That takes a bit of a bite out of the battery, so I hope they go with a heatpump system for the Model S. I also want a Webasto like diesel/oilbased heating system for cold climates, but I'm not sure if I'm getting that.

Cobos

[jkirkebo]

There should be no need for a Webasto (or similar) if they use a heatpump. 1.5kW for heating will give you a ~10% loss in mileage which for me at least is very acceptable. And I also live in Norway

The newer heatpumps give good performance down to -20C and works down to -26C. There should of course be a resistance heater as backup.

[eledille]

Some of us need to cross the mountains in the winter. That sometimes means waiting for snow clearing equipment for hours in very low temperatures and high winds, so I certainly want a diesel heater. The lack of a diesel heater as an option is not a total showstopper, as one can be installed later on. But a factory installed unit would obviously be better and probably less expensive too.

I think they should go for a heat pump as standard and an additional diesel heater as an option. Burning off the power in a resistor is just silly when you can get at least three times as much heat for your electrons with a heat pump. Besides, air cooled resistance heaters burn dust. You want a water cooled unit, but that will probably cost more than a heat pump, as only minor modifications of the AC unit are needed (a few computer controlled valves and a reversible pump).

[PaulM]

I too have thought about the benefits of a fuel powered heater (gets cold in Canada). Some old VW Beetles had a gas heater since you didn't get much heat from the air cooled engine. Although I have not found one yet, a Webasto type heater which could run on a small propane tank (like the ones used for camping) would be ideal. Coleman makes a propane water heater for camping so it should be pretty easy to do (http://www.coleman.com/coleman/colem...ct_id=2300B700).

However as jkirkebo indicated above, the new heat pumps have much better performance than in the past, the only problem is I don't think there are any suppliers building heat pumps in the automotive industry, only residential. Remember, 99.999% of current vehicles have more than enough waste heat to heat the cabin so why would anyone bother developing a heat pump, only a straight A/C is required. Tesla would have to design their own and I think they have enough on their plate already. GM designed a heat pump for the EV1 but they also spent a billion dollars on its development. Even Nissan went with resistive heater for the Leaf. (KISS)

I am told that a heat pump is simply an A/C running backwards so Tesla may be able to get an A/C supplier to modify their A/C unit to enable running as a heat pump but I don't know how efficient it would be. I am certain that all EV manufacturers will eventually go this route, I just don't know if it will be in the Model S version 1.0.

Another thing to consider is that the Model S motor will be liquid cooled and even if it is about 90% efficient, it will still generate quite a bit of heat. Having a heat pump extract heat from the coolant instead of from the air would be much more efficient.

[eledille]

Why propane? We have a diesel powered Webasto Air Top 2000 unit in our Think City which works just nicely. The same unit is available in gasoline, biodiesel and ethanol versions. It uses between 0.2 and 0.4 liters per hour and generates 1 to 2kW of heat. The difficulty is where to place the fuel filler neck and exhaust pipe. Think solved that by placing the tank and filler assembly behind the rear license plate, which is tilted upwards to get at the filler cap. If you plan to have the tank and filler inside the car I can understand the concern (diesel is messy), but then I think ethanol would be OK.

To get maximum efficiency from a combined A/C and heat pump unit, it needs a computer controlled choke valve that separates the high and low pressure parts of the system, a pump that will work in both directions, and a pump motor drive capable of many power levels in both directions. This is now less expensive than it used to be. Modifying an automotive A/C design to do this might be expensive, but then the Model S is a high end car, the "reduced range in cold weather"-argument shows up quite often, and the Model S will be made in much higher numbers than the roadster, though fewer than the Leaf. I don't know how it all adds up, but I hope for the best.

Toyota had a heat pump in their RAV4 EV, I believe, so Toyota has done it before. Anyway, as so many new electric vehicles are going to hit the roads in the next few years, I would have thought that some supplier would be interested in doing this.

If they end up with a resistive heater, then they really need to offer a fuel-powered unit.

I agree about extracting waste heat from the motor, but I think that that might be a bit challenging. If the battery, pem and motor are on the same cooling circuit they will need to make sure that the heat pump does not negatively affect the temperature of the battery. They might need sensors, multi-way valves and firmware to control the whole thing.

[araxara]

Now that some people actually have a Model S, I would think there would be more information available regarding the type of heating system used in the car. I can't find any information online. Maybe some here knows? If the Model S uses a heat pump, I would think that Tesla would like to advertise this. But their silence is starting to worry me.

[Jason S]

Heck, I can't tell ya how the heater works in any of the cars I've ever had. Where would I look in the manual?

[spleen]

I'm pretty sure that I've heard that it's a heat pump but can't find a confirmation online currently ...