Energy consumption for Preheating

[David99]

After the recent update I wanted to see how the battery heater feature works and how much energy is used doing so.

Had the Model S parked outside overnight in -22 C (-7 F). In the morning the battery temperature was -6 C (21 F). I used the app to preheat the car for about 40 min and measured the energy consumption via CAN bus.

Here is a graph of battery temperature and battery power.

The cabin heater and battery heater combined use up to 11 kW. You can see how the battery temperature goes up to 12 C (54 F). So it seem the battery heater continues to run up to 12 C. Usually it shuts off once the battery has reached 8 C (46 F). You can see the drop in power consumption in the graph.

For the entire preheat session the car used aprox 7.5 kWh of energy. When the car is plugged in, this power comes from the grid. In my case I did not have it plugged in to be able to measure the energy.

 

[David99]

To compare, here is the graph of a charging session started in the morning, when the car was parked overnight. The charging doesn't actually start right away. When the battery is below 0 C (32 F) it can't be charged as it would damage it. So the car starts to heat up the battery. Once it reaches 0 C it starts to charge it. I was only at a 24 A outlet so the charge power is limited. The battery heater continues to run until the battery reaches 8 C (46 F). After that it shuts off and all power is used to charge the battery. Interesting to see how the battery temperature drops once the battery heater is off. After all the was was still outside in very cold weather.
To calirify: The graph shows zero charge power in the beginning. This is a little confusion. The power is measured at the battery, not the charger. The charger provides just as much power as is needed to run the battery heater which results in zero. After 16 min or so, the battery reaches 0 and now you see a small amount of power going into the battery. The entire time though, the car draws 5.6 kW (the maximum at this location) from the grid. The green line is battery Ampere.

 

[DerekH]

After the recent update I wanted to see how the battery heater feature works and how much energy is used doing so.

Had the Model S parked outside overnight in -22 C (-7 F). In the morning the battery temperature was -6 C (21 F). I used the app to preheat the car for about 40 min and measured the energy consumption via CAN bus.

Here is a graph of battery temperature and battery power.
View attachment 268813
The cabin heater and battery heater combined use up to 11 kW. You can see how the battery temperature goes up to 12 C (54 F). So it seem the battery heater continues to run up to 12 C. Usually it shuts off once the battery has reached 8 C (46 F). You can see the drop in power consumption in the graph.

For the entire preheat session the car used aprox 7.5 kWh of energy. When the car is plugged in, this power comes from the grid. In my case I did not have it plugged in to be able to measure the energy.

I am new to knowing the car. How do you know what is the battery temperature? Does this apply to model X also?

 

[okcorral]

What OBDII sensor are you using? And software? I’ve been looking for a specific Tesla app. I already have an Bluetooth OBDII sensor.

 

[Tdreamer]

After the recent update I wanted to see how the battery heater feature works and how much energy is used doing so.

Had the Model S parked outside overnight in -22 C (-7 F). In the morning the battery temperature was -6 C (21 F). I used the app to preheat the car for about 40 min and measured the energy consumption via CAN bus.

Here is a graph of battery temperature and battery power.
View attachment 268813
The cabin heater and battery heater combined use up to 11 kW. You can see how the battery temperature goes up to 12 C (54 F). So it seem the battery heater continues to run up to 12 C. Usually it shuts off once the battery has reached 8 C (46 F). You can see the drop in power consumption in the graph.

For the entire preheat session the car used aprox 7.5 kWh of energy. When the car is plugged in, this power comes from the grid. In my case I did not have it plugged in to be able to measure the energy.

This would seem to confirm that battery pre-warming is in fact available while unplugged. There has been some conflicting information on this out there (the Electrek article on this new feature stated you must be plugged in to use it, while the mobile App release notes stated it's desirable to be plugged in [but not required]).

Great information - thanks for posting.

 

[David99]

Yes the battery heater is definitely working without being plugged in!

I'm using an app called Scan my Tesla (Android only). It requires a Bluetooth OBD dongle and an adapter from the car to the Bluetooth dongle.

The battery temperature is not available to see in the car. I wish Tesla would give us simple access to the data.

 

[okcorral]

Yes the battery heater is definitely working without being plugged in!

I'm using an app called Scan my Tesla (Android only). It requires a Bluetooth OBD dongle and an adapter from the car to the Bluetooth dongle.

The battery temperature is not available to see in the car. I wish Tesla would give us simple access to the data.

Thanks. Bummer, I have an iPhone.

 

[Marcira]

It looks like when I use the Tesla App and preheat the cabin, even when unplugged, a small red battery symbol appears in the middle of the screen. I assume this indicates that the battery is being heated in addition to the cabin. Therefore, I assume I am using a lot more energy then before this feature. This could be a concern if I need the extra battery range for my destination. Is there a way to turn off this feature?

 

[st50maint]

It looks like when I use the Tesla App and preheat the cabin, even when unplugged, a small red battery symbol appears in the middle of the screen. I assume this indicates that the battery is being heated in addition to the cabin. Therefore, I assume I am using a lot more energy then before this feature. This could be a concern if I need the extra battery range for my destination. Is there a way to turn off this feature?

I believe range mode will disable this feature.

 

[Snowstorm]

7.6kWh is a lot of energy, I would definitely not run that unless plugged in, and even then only during off-peak electricity hours. I guess I may run it for 5-10 min before getting in just so the cabin is not as cold.

Otherwise, I would think driving with a cold soaked car would be more efficient as at least you are not heating the car for any longer than needed and some of the waste heat form movement would be used for battery heating.

 

[Marcira]

I believe range mode will disable this feature.

The only problem with changing it to range mode, is that you can not do this from the app and you may be quite far from the car. So there should be a way to chose to heat the battery or not if you wish to heat the cabin.

 

[Gromit]

The only problem with changing it to range mode, is that you can not do this from the app and you may be quite far from the car. So there should be a way to chose to heat the battery or not if you wish to heat the cabin.

But the battery heater will turn on and burn energy when you drive the car so the energy will be used anyway, no?

 

[David99]

7.6kWh is a lot of energy, I would definitely not run that unless plugged in, and even then only during off-peak electricity hours. I guess I may run it for 5-10 min before getting in just so the cabin is not as cold.

Otherwise, I would think driving with a cold soaked car would be more efficient as at least you are not heating the car for any longer than needed and some of the waste heat form movement would be used for battery heating.

The battery heater comes on whether you drive or not. I believe turning on Range Mode will reduce battery heater use. I have not been able to test it and now I'm back home in Los Angeles where it never gets cold enough to do any cold weather testing

 

[hotgrips]

I have a 2014 Model S P85D and just ordered the Founder's Edition 2020 Roadster this morning. Has anyone been working on the possible use of the battery in the Model S as an emergency house backup power source?

I have 30kW of Sharp ND-216U1F solar panels but with the grid-tied requirements for auto-disconnect when the grid is down, it would be nice to be able to use that battery to power essential items in a winter storm, like a furnace and water pump. With UL approved grid tied inverters, when the grid goes down due to an ice storm as an example, your solar panels cannot send any power to the house.

Such a feature with the 2020 Roadster would be especially useful since it will have considerable kWH capacity.

While I understand that Tesla Motors would not want owners using the Superchargers and using the car to feed power to a home, perhaps there is a way to do? Anyone know?

 

[hotgrips]

On the possible use of the battery pack for feeding power to the house, is there any creative thought out there on how it might be done? Because of my 150 216w solar panels, I find it is not worth the time to go to our local supercharger anymore. With New Hampshire's Public Utility Commission rules on Net-Metered grid tied solar, you can bank summer excess kWH credits for use in winter, and the end result is no heating bill (we use a heat pump so it is all electric) and virtually no electric bill annually except for the minimum default service charge of $12./month. We have so much excess power that I find myself leaving the Tesla heated to 60 F in the winter, which costs nothing due to the kWH extra credits built up from the previous summer.

It's amazing how well the traction control works in the Model S. My 2015 Porsche 911 Turbo with AWD is so horrible in the snow that I stopped using it when there is any snow in the driveway. It slithers around with the OEM tires like it is on glare ice, cannot brake or give it any throttle without feeling like I am going to lose it. Yes, if I got dedicated winter tires instead of the Pilots then it probably would work better. The Tesla Model S in contrast is on the OEM tires and works fine. So well, that I never installed a set of mounted Hakipalitta with studs on my S.

I had an odd parking situation at a local store where my front plstic under the bumper just hung down low enough to catch the concrete parking "curb". It must have been a 1/4" interference. When I left the store with no cars around me I heard this horrible sound, and touched the brakes just 12" from the concrete curb. To my horror the front bumper, nose, and plastic panel underneath had been ripped away and the plastic panel was clearly caught on the concrete. I raised the suspension to "very-high" and still could not get uncoupled. I took some strips of a wood pallet from the store to get free of the concrete curb, pushed the panels back into place, and used a roll of duct tape to hold it all together. Unfortunately, I could see the retaining clips were all torn away from the dislodged bumper, headlights, underpanel, and wondered if others have experienced a similar problem on the 2014 models. Perhaps they improved it in later years, so that the black panel under the bumper cannot get trapped like that. I don't dare contact the insurance company because they don't charge me much for the "collision portion" of the bill and I don't want to jeopardize that for the future. Any way of dealing with the torn fasteners and torn clips?
Next time I have it on a lift in a warm garage I will do what I can, and fabricate something to prevent any step on that black panel from catching on anything.

 

[David99]

I have a 2014 Model S P85D and just ordered the Founder's Edition 2020 Roadster this morning. Has anyone been working on the possible use of the battery in the Model S as an emergency house backup power source?

EVTV has a box that connects to a bare Tesla Model S/X battery and let's you charge it via solar or other sources. You can also hook up an inverter and power your house or whatever you want. It does not work as long as the battery is still installed in a car. You would have to un-mount the battery.

 

[Elmer99]

Does the energy used to preheat the car get added to the KWh measured by car? If yes, it will skew the KWh per km #?

 

[minderbinder]

Does the energy used to preheat the car get added to the KWh measured by car? If yes, it will skew the KWh per km #?

No, it doesn't. The car only records kWh when it's on (butt in seat, basically).

 

[RDoc]

But the battery heater will turn on and burn energy when you drive the car so the energy will be used anyway, no?

As I understand it, the waste heat from the motor and battery discharge when driving also helps warm the battery. I don't know how much the effect is though compared to the battery heater.

 

[David99]

Does the energy used to preheat the car get added to the KWh measured by car? If yes, it will skew the KWh per km #?

It will measure it but it will not show it to you as kWh. It will also not show it in your trip energy consumption. You will see the range drop as the energy is used from the main battery. Although If you drive, the energy used by the battery heater will be included in the trip consumption. That's just how Tesla does it. If the car is not moving, the energy usage is not shown in the trip consumption. If the car it moving it will show up.

Internally the car will of course always keep track of any energy coming out or going into the battery to properly calculate the state of charge.