Manually warm up battery?

[pt19713]

At a V3, I was able to get the packs to 131F/55C.
Ambient temps were 33F/0.5C.

Pre-conditioning in the garage at home, the front motor doesn't appear to go above 210F but at the SC, I've gotten it to 252F/122C

 

[Sam1]

At a V3, I was able to get the packs to 131F/55C.
Ambient temps were 33F/0.5C.

Pre-conditioning in the garage at home, the front motor doesn't appear to go above 210F but at the SC, I've gotten it to 252F/122C

130 is where active cooling kicks on, so unless you're running the car hard on the track or like here in Vegas when it's 119 degrees in August, they rarely stay above 130 long at all.

 

[jim0266]

The 2021 models are confusing a bit because of the heat pump and octovalve so things are a bit different. 2018-2020 models like mine do heat the battery when you heat the cabin, by generating heat in the motors. Motor heat goes to the battery while PTC heat goes into the cabin. There is no separate switch unfortunately, and no way to disable battery heating either. I believe this will heat the battery until it reaches around 21C, which is where you get most if not all of your regen back. 21C is much higher than the temperature where the snowflake disappears. You will also have most of your acceleration power at that temperature. There seems to be other factors that influence maximum regen and power output... maybe recent firmware changes. I was sure that by 21C I had full 85kW of regen but the last time I checked with ScanMyTesla I only had around 70kW at that battery temperature (at 89% SOC).
Preconditioning for a supercharger will heat the battery higher than 21C, I just don't know what the upper limit is. I've arrived to a SC at ~35C I believe, once. I don't drive enough to have multiple test points to compare.

To add more evidence to this reply...

2019 Model 3 LR (w/o heat pump) battery conditioning test. The goal of the test was to see how turning on the HVAC only to preheat the cabin effected the battery temperatures in a cold climate. The car was plugged into L2 during this test and the HVAC only is started. Charging does not start until noted below.

All the stats below were gathered from ScanMyTesla. SMT reports both a SOC and a SOC Expected value. The SOC Expected number falls below the SOC number when the pack is below around 68°F. The SOC expected value is what’s shown on the cars screen and used to calculate expected range. This value is also used by apps like Stats to calculate range and battery degradation. I have photos from another test showing this at the ScanMyTesla post.

Temps were in the lower to mid 20’s for several days. Car not driven or plugged in for those days before start of test. Car was stored in an unheated garage.

The stats

Start cabin heating at 10:47
Min 37.4 °F
Max 38.3 °F
Avg 37.9 °F
SOC 42.1
SOC Expected 37.5

10 mins 10:57 (3 degree increase)
Min 41 °F
Max 41 °F
Avg 41 °F
SOC 41.9
SOC Expected 37.5

20 mins 11:07 (9.9 degree increase)
Min 47.3 °F
Max 48.2 °F
Avg 47.8 °F
SOC 41
SOC Expected 39.9

30 mins 11:17 (17.1 degree increase)
Min 54.5 °F
Max 55.4 °F
Avg 55 °F
SOC 40.8
SOC Expected 39.9

40 mins 11:27 (24.7 degree increase)
Min 62.6 °F
Max 62.6 °F
Avg 62.6 °F
SOC 40.8
SOC Expected 40.4

50 mins 11:37 (29.2 degree increase)
Min 66.2 °F
Max 67.1 °F
Avg 66.7 °F
SOC 40.9
SOC Expected 40.4

—L2 charging Started—

2 hours hours after start of preconditioning and 1 hour of charging
Min 70.7 °F
Max 70.7 °F
Avg 70.7 °F
SOC 50.1
SOC Expected 49.9

3 hours later. End of charging at 60%
Min 73.4 °F
Max 74.3 °F
Avg 73.9 °F
SOC 59.9
SOC Expected 59.8

 

[Brock-WI]

Jim I am confused, did you open the door and physical start the HVAC and left the door cracked?

I also have Scan My Tesla and actually did a similar thing this am. I think the difference may be I have a 2018 SR (single motor). All I did was tell the car to start charging, never opening the car. The pack started at 28F. SMT was showing it charging the pack with 3.5kW and the rear (only) stator running consuming 3.5kW as well. After about 1 hours the pack was up to 49F and that is when the rear stator stopped running / heating the pack and then the pack started charging at 7.5~8kW. Really what I was testing for was if the car warms the pack for just AC charging and it does. I assume it does the same thing when you set a "depart time" backing up and guessing how long it needs to warm the battery and charge it to the set point, but it seems to get the pack to about 50F.

 

[GtiMart]

The car will heat the battery to around 10C when AC charging. It will go higher, to around 20C, when preheating before a drive.

 

[designrs]

M3P . Cooler temps, the battery is not nearly as responsive/powerful until (i'm guessing) a certain battery temp is reached. About 50 degrees outside, started at 90% capacity, raced a CTSV at 80%, the CTSV pulled on me when normally the same car loses fairly bad. Car felt underpowered. Run the battery down to 60% the same day, and the car feels like it has more power than it did at 80%. (guessing the batteries had warmed up by then)

I’d worry more about warming up the tires before pushing it that hard. (Not burnouts, but just normal driving.) These “opportunities” of ambition often occur shortly after leaving a parking lot with cold tires. Unfortunately, many great cars have been damaged even with advanced traction control.

 

[jim0266]

Jim I am confused, did you open the door and physical start the HVAC and left the door cracked?

I also have Scan My Tesla and actually did a similar thing this am. I think the difference may be I have a 2018 SR (single motor). All I did was tell the car to start charging, never opening the car. The pack started at 28F. SMT was showing it charging the pack with 3.5kW and the rear (only) stator running consuming 3.5kW as well. After about 1 hours the pack was up to 49F and that is when the rear stator stopped running / heating the pack and then the pack started charging at 7.5~8kW. Really what I was testing for was if the car warms the pack for just AC charging and it does. I assume it does the same thing when you set a "depart time" backing up and guessing how long it needs to warm the battery and charge it to the set point, but it seems to get the pack to about 50F.

Hi Brock, I have a LR RWD. I did not open the car door. I started the HVAC from the app.

Thanks, what you did was my next test. I was wondering if the car would start charging immediately if the pack was at low temps or first warm the pack and then start charging. Interesting to note that 49F is the point charging starts. Your question about depart time is one that I wonder about too when it comes to preheating the battery and adjusting the time needed.

I did find this at https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=48711&flag=1
"If the battery temperature is near or below freezing temperatures, normal charging will not occur. The vehicle will identify this condition and will begin heating the battery coolant and circulating the coolant to raise the battery temperature to enable charge. When the pack temperature rises to a temperature within the allowable charging range, heating will reduce or stop and charging will commence."

 

[SigNC]

lots of misinformation in this thread and I wish tesla would at least document what is happening for people that want to know the complexity. From what I can tell if you turn on cabin heat (remotely, not in the car) and the battery is below around 50f it will heat the battery up to about that point. So, you will get in and there will be a little bit of regen limitation but certainly nothing like if you didn't preheat. As soon as you get in the car, the preheating of the battery turns off. If you set your car to maintain climate, when you get out if the battery is below the ~50f it will again start warming it as long as you are no longer in the car. The key is climate on, nobody in the car for the battery heaters/motor heat (or as bjorn calls it, afterburners) to be running. You can easily see if this is happening by looking in the app under climate and seeing the red battery icon. Being able to see this in the app was added maybe....2 months or so ago. It's also nice to know that if you leave your car preheating with a very cold battery and you don't need regen or plan to fast charge, you are likely heating up your battery to 50f for basically no reason. I usually just do a 5min or so cabin preheat and hit the road unless I'm planning on going to a supercharger.

TL;dr if you turn on climate remotely and your battery is below 50f it will warm the battery.

P.S.- This information is ESPECIALLY helpful if you've left your car outside in very cold climate and plan on supercharging soon after your departure. Let the car get the battery up to 50f before you leave, then put SC in the navigation when you leave so it further heats on your way.

 

[jrweiss98020]

Preconditioning for a supercharger will heat the battery higher than 21C, I just don't know what the upper limit is. I've arrived to a SC at ~35C I believe, once. I don't drive enough to have multiple test points to compare.

How do you know what your battery temp is?

 

[Brock-WI]

So I saw the pack temp at 28F and it was charging the pack at 3.5kW. I wonder at what pack temp it will heat up the pack up before charging from AC at all. According to that article it was below freezing, which my pack was, but still charging at 3.5kW. Maybe I was right at that limit?

My other question is if say you leave the car plugged in overnight on 120vac outside at -10F or -23C with no departure, at what temp will it wake up and start warming the pack? In other words how cold will the pack get if left on its own plugged in vs on its own battery.

 

[GtiMart]

How do you know what your battery temp is?

Using ScanMyTesla.

 

[user212_nr]

Had a question, and seen someone else with the same inquiry on reddit.

M3P . Cooler temps, the battery is not nearly as responsive/powerful until (i'm guessing) a certain battery temp is reached. About 50 degrees outside, started at 90% capacity, raced a CTSV at 80%, the CTSV pulled on me when normally the same car loses fairly bad. Car felt underpowered. Run the battery down to 60% the same day, and the car feels like it has more power than it did at 80%. (guessing the batteries had warmed up by then)


Thanks

Set the car's acceleration to "Insane+" and it will heat the battery, in addition to preconditioning. I'd guess you might already be on this mode, so maybe temp is not the problem.

You are correct at the loss of power correlating with the battery percent lower. Max power = current x voltage. The max current is the same so as battery voltage drops so does the max power (simplified version). Charging to 100% will give you the fastest times.

 

[Gasaraki]

Set the car's acceleration to "Insane+" and it will heat the battery, in addition to preconditioning. I'd guess you might already be on this mode, so maybe temp is not the problem.

You are correct at the loss of power correlating with the battery percent lower. Max power = current x voltage. The max current is the same so as battery voltage drops so does the max power (simplified version). Charging to 100% will give you the fastest times.

This the Model 3 forum.