State of Charge plummeting in cold weather

[Shelburne]

I'm just entering my 4th winter with my 2020 M3LR. Yesterday I parked the car at 12:30PM. It had 154 miles of range. The temperature was just above freezing. Overnight the temperature got down to about 26 degrees(F). Now, after being parked for about 22 hours the car is down to 140 miles of range. I don't remember the cold having this much of an impact on my cars range in previous winters and am wondering if something else could be contributing to this sharp drop in range. Any thoughts???

 

[bruce4000]

One thing that’s uses about 5% a day is if sentry mode is on.

 

[ucmndd]

I’d speculate that recent firmwares have gotten more aggressive about locking out some capacity in the cold. Does the “missing” range show us as blue on the range bar in the app?

 

[jjrandorin]

I’d speculate that recent firmwares have gotten more aggressive about locking out some capacity in the cold. Does the “missing” range show us as blue on the range bar in the app?

My first thought was to ask if there was snowflake on the display. If so, then that is the likely explanation for this, and it (the range) would return when the battery warms up.

 

[GtiMart]

I second that. I have a 2020 M3 LR AWD and I can see up to a 7% SOC "discrepancy" (when it's pretty cold) between the actual SOC if you only look at voltage and the SOC reported in the car. When that happens you see the blue snowflake and the battery charging diagram shows a portion of the slider in blue. This tries to estimate how much less energy you will be able to extract from the pack when it's at that temperature. You haven't "spent" that energy.
EDIT: This might appear a bit earlier than before, I don't know, but I've seen up to 7% difference in years past as well so the principle certainly isn't new.

 

[Shelburne]

My first thought was to ask if there was snowflake on the display. If so, then that is the likely explanation for this, and it (the range) would return when the battery warms up.

Yes, the old blue snowflake is showing up in the App so I just started to precondition the battery and will check it's range in about 20 minutes when I leave the house. Thanks

 

[jjrandorin]

Yes, the old blue snowflake is showing up in the App so I just started to precondition the battery and will check it's range in about 20 minutes when I leave the house. Thanks

20 minutes may not be enough time to warm the battery. For this discussion, whats relevant is what the range is when there is no more blue snowflake.

Since you say you have a blue snowflake, that means the battery is cold, so is the explanation for why the range is "missing". It will return when the battery is warm, but it could take a long time for the battery to be fully warmed.

 

[Shelburne]

20 minutes may not be enough time to warm the battery. For this discussion, whats relevant is what the range is when there is no more blue snowflake.

Since you say you have a blue snowflake, that means the battery is cold, so is the explanation for why the range is "missing". It will return when the battery is warm, but it could take a long time for the battery to be fully warmed.

I just finished preconditioning the battery. The state of charge, as a percentage, didn't change and it only shows one additional mile of range in the App.

 

[jjrandorin]

I just finished preconditioning the battery. The state of charge, as a percentage, didn't change and it only shows one additional mile of range in the App.

you just finished pre conditioning the CABIN, you did not fully heat the battery.

 

[jsmay311]

I’ve been awfully confused on the topic of whether or not heating the cabin through the app does anything to heat the battery.

Tesla’s Cold Weather Best Practices suggest that it does:

“In the mobile app, navigate to Climate to customize the temperature at which you want to heat the cabin. This also warms the high voltage Battery as needed.”

I’ve also read suggestions on forums that this will only heat the battery when the car is plugged in.

But I just tested my 2018 Model 3 (without heat pump) and turning on cabin heating through the app does not activate battery heating regardless of whether it’s plugged in or not. (This was with a blue snowflake showing and a battery temp of 40F and a 4% difference between available and actual SOC%.)

So what gives? Does the info in the Cold Weather Best Practices only apply to cars with heat pumps? Or does “as needed” only apply when the battery is extra cold?

 

[jsmay311]

As for the OP… it’s normal. And even if the car did actively heat the battery, doing so would use up energy in the process, so I wouldn’t expect the displayed charge percent to increase. (The benefit of the increased battery temp would be offset by the energy used to heat it up.)

 

[E90alex]

I’ve been awfully confused on the topic of whether or not heating the cabin through the app does anything to heat the battery.

Tesla’s Cold Weather Best Practices suggest that it does:

“In the mobile app, navigate to Climate to customize the temperature at which you want to heat the cabin. This also warms the high voltage Battery as needed.”

I’ve also read suggestions on forums that this will only heat the battery when the car is plugged in.

But I just tested my 2018 Model 3 (without heat pump) and turning on cabin heating through the app does not activate battery heating regardless of whether it’s plugged in or not. (This was with a blue snowflake showing and a battery temp of 40F and a 4% difference between available and actual SOC%.)

So what gives? Does the info in the Cold Weather Best Practices only apply to cars with heat pumps? Or does “as needed” only apply when the battery is extra cold?

It only warms the battery to slightly above freezing (I think I saw ~3°C target in another thread).

It will not keep warming the battery until it’s actually what we would consider “warm” or optimal operating temp.

 

[Shelburne]

you just finished pre conditioning the CABIN, you did not fully heat the battery.

Respectfully, I think you are wrong. The blue snowflake had disappeared on the App before I went out to the car. It also wasn't showing on the touch screen. However, after I had driven to the grocery store, I noticed that I had onlynused 4 miles of range to get there when I usually use 9 miles of range. So maybe the car corrected itself and "restored" some od that range that seemed to have disappeared before I preconditioned the battery.

 

[jjrandorin]

Respectfully, I think you are wrong. The blue snowflake had disappeared on the App before I went out to the car. It also wasn't showing on the touch screen. However, after I had driven to the grocery store, I noticed that I had onlynused 4 miles of range to get there when I usually use 9 miles of range. So maybe the car corrected itself and "restored" some od that range that seemed to have disappeared before I preconditioned the battery.

I was going by what you said earlier. I had a bunch of stuff typed here but when I re read it, it sounded somewhat argumentative which isnt the tone I was going for, so I removed it.

Range locked out by the blue snowflake normally comes back when that is gone.. but its definitely 100% positive for the battery to be cold, yet not cold enough to display a blue snowflake. Thats the condition I normally see here in southern california, as in general where I live doesnt get cold enough to lock out battery range (or it didnt... this morning I had blue on my charging bar when I looked in my app to turn on hvac before I left).

 

[P3dStealth]

I often see this. My battery percentage just drops while parked in winter. It doesn't recover when you warm up the battery. You will also get the blue snowflake and line that will go away eventually.

Maybe it has to do with voltage drop from the cold. It just reads lower. Then to heat the battery I'm burning energy anyway so it never really recovers. Just guessing though. I have no idea why it happens but it's done it forever.

 

[SageBrush]

“In the mobile app, navigate to Climate to customize the temperature at which you want to heat the cabin. This also warms the high voltage Battery as needed.”

The specific heat of the pack is in the range of 850 J/Kg*K. From Bjorn's videos, I think active pack heating is in the range of 6 kW. A - 80 kWh pack weights about 800 Kg

So you tell me: how many degrees C will the pack heat up per minute with directed pack heating ?
My arithmetic says 0.5 C/min if 6 kW of heat is directed to the pack. If cabin heating is splitting the heat, then the pack heats up 0.25 C/min

 

[Maki22]

The specific heat of the pack is in the range of 850 J/Kg*K. From Bjorn's videos, I think active pack heating is in the range of 6 kW. A - 80 kWh pack weights about 800 Kg

So you tell me: how many degrees C will the pack heat up per minute with directed pack heating ?
My arithmetic says 0.5 C/min if 6 kW of heat is directed to the pack. If cabin heating is splitting the heat, then the pack heats up 0.25 C/min

You also need to add heatloss because of the cold ambient temperature that will keep sucking the heat out of the battery

 

[SageBrush]

You also need to add heatloss because of the cold ambient temperature that will keep sucking the heat out of the battery

Yes indeed, although after a cold soak the temperature gradient may only be a few degrees

 

[KenC]

Cold day, 37F, blue snowflake when I got in the car. As you can see, after driving about 9miles, my SOC started to go up. No, there's no elevation drop or coasting, the battery is recovering some of its lost range as it warms up.

 

[P3dStealth]

Cold day, 37F, blue snowflake when I got in the car. As you can see, after driving about 9miles, my SOC started to go up. No, there's no elevation drop or coasting, the battery is recovering some of its lost range as it warms up.
View attachment 1000180

It says "going downhill saved 1.2%".