# Model 3 battery pre-heating - 2019.40.2 v 2019.40.50



## NorfolkMustard

I was listening to the latest podcast yesterday, and thought @TrevP et al may find this interesting as they mentioned the lack of a dedicated battery heater on the Model 3 and Tesla's alternative approach to battery heating.

I've been tapping into the tesla api for a couple of months and logging the output. After noticing that the regen was normal/full even on recent cold mornings when it hadn't been previously, I did some digging.

Both graphs show the same morning routine over two separate days/firmware versions. The car is plugged in (10a/240v TMC), outside temp and inside temp-target the same. I turn on climate remotely in the app about 30mins before I head out for the first drive of the day. I don't adjust any settings, just app > climate > turn on climate

The top graph show v2019.40.2
After the initial spike of power (the orange bars show power (kW) being drawn from the battery+TMC as-at each minute's api reading i.e. it's not a cumulative kWh energy usage) it settles to 2kW after about 4 mins - enough to keep the cabin at the desired temp (blue line)










The next graph shows the same morning routine but with 2019.40.50
You can see the power being drawn stays at a sustained 10kW for much longer, about 20 minutes, well after the cabin is at the desired temperature.
To me this shows tesla have changed the battery pre-heating in this latest firmware. I like it - predictable regen from the get-go










I also have scan-my-tesla gubbins installed and you can see from that the front & rear stators were toasty (80-90ºC) and the battery coolant inlet was still higher (31ºC) than the battery pack 22ºC (cell-temp-mid) at 10:20am - the battery continues to be warmed by the coolant flowing around them even after the stators stop drawing power


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## wst88

Thank you for checking into this.. It seemed like something had changed based on how few dots were left on the regen line after warmup as compared to last winter. Great info!


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## TrevP

@NorfolkMustard do you have a single or dual motor car? 
Fun thing: navigate to a Supercharger and watch the kW going into the motors during preconditioning, especially while not moving. You should see about 3.7kW going into them, even while not moving. If you have the dual motor car you'll feel the PMAG "cogging" from the motor at low speeds. Pretty cool how Tesla is stalling the motors to generate extra heat!


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## JWardell

Yes, preconditioning with HVAC will also start warming the battery.
It should be noted that battery heating won't start until after the cabin has reached the desired temperature, at least in my case where the 5kW wall connection will not support both 7kW heating and the 3-6kW it uses for battery heating.
Yet another reason why I feel the 2019.40 firmwares are really making this car feel feature complete after a year of really dialing in the full potential of the Model 3 powertrain.


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## Frully

NorfolkMustard said:


> I was listening to the latest podcast yesterday, and thought @TrevP et al may find this interesting as they mentioned the lack of a dedicated battery heater on the Model 3 and Tesla's alternative approach to battery heating.
> 
> I've been tapping into the tesla api for a couple of months and logging the output. After noticing that the regen was normal/full even on recent cold mornings when it hadn't been previously, I did some digging.
> 
> Both graphs show the same morning routine over two separate days/firmware versions. The car is plugged in (10a/240v TMC), outside temp and inside temp-target the same. I turn on climate remotely in the app about 30mins before I head out for the first drive of the day. I don't adjust any settings, just app > climate > turn on climate
> 
> The top graph show v2019.40.2
> After the initial spike of power (the orange bars show power (kW) being drawn from the battery+TMC as-at each minute's api reading i.e. it's not a cumulative kWh energy usage) it settles to 2kW after about 4 mins - enough to keep the cabin at the desired temp (blue line)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The next graph shows the same morning routine but with 2019.40.50
> You can see the power being drawn stays at a sustained 10kW for much longer, about 20 minutes, well after the cabin is at the desired temperature.
> To me this shows tesla have changed the battery pre-heating in this latest firmware. I like it - predictable regen from the get-go
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I also have scan-my-tesla gubbins installed and you can see from that the front & rear stators were toasty (80-90ºC) and the battery coolant inlet was still higher (31ºC) than the battery pack 22ºC (cell-temp-mid) at 10:20am - the battery continues to be warmed by the coolant flowing around them even after the stators stop drawing power


Anecdotally, I had one of the coldest mornings to date this winter (-20C, full cold soaked battery). I usually only preheat the car about 3 minutes to get the cabin warm, and I indeed have huge blue snowflake...and limited accel, no regen. This morning I preheated the car for 30 mins, and sure enough, I lost a fair chunk of range (that 10kw draw it seems), but had no cold soak and had some regen at the start of the trip...on one of the coldest days. Absolutely adding my love of warm battery.


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## NorfolkMustard

@TrevP Mine's a dual-motor. Agree with the 2 x 3-3.5kW stator power draw for this. Would be good to see what a single motor equivalent would be. 1 x 3kw or 1 x 6kw

Also noted:-

It does this whether plugged in or not
If plugged in it will use shore power to supplement battery power - *but*, it doesn't warm the battery this way if you've set it purposely charging. i.e. if you see an active "Charging" status in the app, then it seems to decide range is your priority, not a warm battery. Which is logical.

i did a test this morning while it was charging ( only on the TMC @ 2kW). I turned on Climate but the power use (total of battery + mains) was only 2kW - enough to run the heaters - even after 10 minutes.
As soon as I hit "Stop Charging" the power use ramped up to 10kW ( 8kW from the battery, 2kW from the mains)


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## rrolsbe

I posted the following on another forum yesterday, some of it is applicable to this thread topic. Regards Note: I have the latest firmware 50.7 if memory serves.

I own a 2018 M3 RWD and the following is some information I gathered using Scan My Tesla app SMT.​​With the car not plugged and the ambient temp around 48F the car draws 3.5KW to heat the traction battery and about 7KW max to heat the cabin for a max total of 10-11KW. When the car is plugged into my [email protected] it supplies 5+KW of the 11KW. The only option I found that would heat the cabin and NOT heat the traction battery, via the traction motor, was camping mode. I did not run the test for very long so I am not sure at what cell temp the battery heating would terminate? I do know that when actively charging the battery heating to accept a 22mph charge rate stops at around 54F. I think heating the traction battery while heating the cabin is new? I can see times where heating the cabin and NOT heating the traction battery might be my preferred option and the only way to do so is using CAMP mode.​​I also monitored the rear motor power, motor torque and brake variables and it appears to regen down to a complete stop, which surprised me, and then after about a second the brake is applied. These reading were observed while set to the single pedal driving mode.​​


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