Unexpected range loss in extreme cold

[jalatontarzan]

So today I had a 220km trip starting with -15C and from midpoint to end about -25C. Not only that but also 6m/s headwind. So very rare and quite extreme conditions. Usually at least wind is closer to zero when temperature is below -20 degrees.

So I estimated my consumption to be 260wh/km which gives total consumption of 57,2kWh. I calculated that 90% (430km rated range, ~65kwh usable energy) will be enough and even give me a little buffer to something unexpected.

About halfway at SOC 50% regen dots appeared and I thought thats weird. Checked from SMT and all temperatures were still around 20 degrees but charging/regen was limited at 45kW. Later on around 30% snow symbol appears with cell temperatures at 15c. Last 30km range started to really plummet and blue section in battery image started to grow. Luckily I managed to get to destination with excactly 0km in displayed range. Average consumption was 250wh/km so there should have been buffer more than enough. While planning the trip I thought that waste heat from motors would keep the battery warm enough to not give me blue "range lock" while driving. Cell temperatures were +12c at the end and car was able to charge immediately without warming the battery. Blue bar disappeared again when SOC was around 30%.

Does anyone know if there is something else than cell temperatures which would cause this capacity lock? Or is it normal in lower SOC even with moderate cell temperatures? Never been so low before and capacity lock has only appeared while stationary.

In hindsight I would charge to 100% to give as much buffer as possible if such extreme conditions, but today time was limited. Its also hard to anticipate for everything especially if no previous experience. Just keep in mind that there might occur quite significant range loss while driving prolonged periods in freezing temperatures which you might not be able to count by calculating only energy consumption.

Manual battery heating would also be cool

 

[Gasaraki]

OK, here's the lowdown for 2021 M3s. (I learned a lot from Teslabjorn).

The heat pump will suck heat from the batteries to heat the cabin because it's more efficient. 2020 and older didn't do this.
What happens is that as you drive the battery gets colder and colder and your charge obviously gets lower and lower. In the 2021 Performance, it seems like that (for now) that the car starts limiting your battery output power at a fairly high state of charge >25%. The 2021 AWD LR seems to tolerate the low battery temperatures better, it doesn't start reducing power till 10%.Of course this depends on the temperature of the batteries. If it's really cold outside, this will be worst.

To combat this you need to use the nav to navigate to a supercharger that is on the way to where you are going, even though you are not going there. Doing this will put the car in preheat mode, keeping the battery warm so you don't get stuck with 0% power out of the batteries.

 

[Sklith]

Maybe Scan My Tesla's cell pack average is a bit misleading because some of the cells are a lot lower than the average. Perhaps only the cells near the inlet are warm while the outlet-end ones are too cold to accept a charge?

Does SMT display coolant flow temperatures leaving the battery pack?

Edit:

Manual battery heating would also be cool

Agreed! This is especially useful for folks planning on DC fast charging soon but don't have the destination marked in the car's navigation at the time. A good example is picking up some food or using a restroom prior to charging up.

 

[camalaio]

Waste heat from driving with a headwind will result in keeping about a 20C-25C delta on temperatures. That is, while driving in -20C, I would actually expect the waste heat to only float you around 0C-5C anyways (but it sounds like you started with a battery much warmer than that).

At low SoC, in my experience, cold hits the battery harder, as you observed as well. Actively heating the battery wouldn't gain you enough energy to offset the energy wasted to get it warmer (that's a lot of thermal mass to heat up!).

 

[AlanSubie4Life]

Later on around 30% snow symbol appears with cell temperatures at 15c

I didn't think this temperature (15C) was anywhere near cold enough (even for a cold-soaked battery) to show a snowflake symbol, at least in past years, assuming it actually reflects the battery temperature (inlet/outlet temps would be a hint as to whether it reflects actual cell temp, I guess).

My understanding is that there are various issues with the software on the the 2021s, revolving around charge rates and cell temperatures. I don't have one, nor do I live in a cold environment, so I have no idea whether this is actually an issue. Anyway, I do wonder whether any such issue may currently be a contributing factor to this issue. There are various aspects of these reports that I have heard:

1) Very slow supercharging compared to prior years.
2) Battery heating being used while charging from AC at 11kW, even when cell temps are already above 15C.
3) Power getting pulled at low SoC.

Etc.

There are two different battery types (LG & Panasonic) in the 2021 LRs, so that also plays a role in differences between vehicles, most likely.

 

[jalatontarzan]

I have old school 2019 LR AWD so no heat pumps. Also not my first winter but was my first +2h drive in such temperaturs.

Maybe Scan My Tesla's cell pack average is a bit misleading because some of the cells are a lot lower than the average. Perhaps only the cells near the inlet are warm while the outlet-end ones are too cold to accept a charge?

Does SMT display coolant flow temperatures leaving the battery pack?

Edit:

Agreed! This is especially useful for folks planning on DC fast charging soon but don't have the destination marked in the car's navigation at the time. A good example is picking up some food or using a restroom prior to charging up.

Yes it shows coolant temperatures. It also shows cell min and max. All temperatures were within few degrees coolant loops included.

Waste heat from driving with a headwind will result in keeping about a 20C-25C delta on temperatures. That is, while driving in -20C, I would actually expect the waste heat to only float you around 0C-5C anyways (but it sounds like you started with a battery much warmer than that).

At low SoC, in my experience, cold hits the battery harder, as you observed as well. Actively heating the battery wouldn't gain you enough energy to offset the energy wasted to get it warmer (that's a lot of thermal mass to heat up!).

Makes sense, and yes, started from DC charger so battery was hot at the beginning. Manual battery heater would maybe be enough to keep battery warm enough with the help of waste heat to prevent capacity lock while driving and give and extra time to operate before temperature equilibrium. As it seems that this equilibrium is way too low for lower SOCs without additional heating.

Range display also would be more accurate since with heater on you could see the actual consumption. So there would be no need to guess when range will disappear and by how much. Waste heat was already almost enough in this case, it was the last 30km when SOC was below 10% when problem started to escalate as range almost plummeted below to distance left. Nearest supercharger was over 300km away so not possible to cheat with navigation, also no any other DC cahrgers in this particular stretch. I know, very rare conditions and quite hardcore segment to drive, probably will be most difficult for me ever.

 

[JCtx]

Hey, where can you check battery temperature? We're going on a long (600+ miles) trip Thursday, and have to leave at 6:30am, when it'll be right around freezing (32F). The high should hit around 65F. My first leg is 135 miles. I should be fine even with heat, and headwind with 90% charge, right? Will definitely heat the cabin and batteries from the app before leaving, probably like 5 to 10 minutes max, which should be enough, but will first start charging the car, so it doesn't suck juice from the batteries. I already tried doing that with car connected and not charging, and it does not suck juice from the wall until the battery drops a percent or two.

Finally, is there a way to heat the battery from the car? I don't like that the app heats both cabin and batteries when turning on 'climate'. It should have TWO separate buttons. You can see a small battery symbol with a snow symbol inside on the right top side of the app, but you can't 'unclick' it, or turn it off. You have to turn climate off. And if you preheat the battery like that, will it stay hot, or cool down, making the waste of energy useless? We'll hit highway speeds about 2 miles from my house.

 

[jalatontarzan]

Hey, where can you check battery temperature? We're going on a long (600+ miles) trip Thursday, and have to leave at 6:30am, when it'll be right around freezing (32F). The high should hit around 65F. My first leg is 135 miles. I should be fine even with heat, and headwind with 90% charge, right? Will definitely heat the cabin and batteries from the app before leaving, probably like 5 to 10 minutes max, which should be enough, but will first start charging the car, so it doesn't suck juice from the batteries. I already tried doing that with car connected and not charging, and it does not suck juice from the wall until the battery drops a percent or two.

Finally, is there a way to heat the battery from the car? I don't like that the app heats both cabin and batteries when turning on 'climate'. It should have TWO separate buttons. You can see a small battery symbol with a snow symbol inside on the right top side of the app, but you can't 'unclick' it, or turn it off. You have to turn climate off. And if you preheat the battery like that, will it stay hot, or cool down, making the waste of energy useless? We'll hit highway speeds about 2 miles from my house.

If your car is plugged it will use grid electricity before battery whether you are charging or not. Just note that net draw can be more than charger can provide when preheating, and then of course energy from battery will be used.

In your case temperatures will not be a problem as long as you count extra consumption for cabin heating and all other "basic" variables. ABRP is excellent tool to help if you don't have much prior experience. If you want to be extra sure, just preheat cabin and battery well, something like 30min. 10min is not enough to warm the battery.

For shorter drives I agree that heating battery is useless and completely wastes energy. For example short drive of 10km, battery -15c, 5-10min preheating for cabin to make it bearable. Now battery is -10c and after drive -5c. What was the point of heating? IMO nothing was gained.

Longer road trips? Juice up every single Wh available from grid and store it also as heat in cabin and battery to make everything more convenient.

Edit. Only way to manually activate battery heating while driving is to set navigation to supercharger and if it's close enough afterburners will kick in. No superchargers close enough? Bad luck. In arctic environment manual battery heating both in car and app which would work both driving and stationary would be very useful.

 

[chrisf60526]

The range loss in cold weather is a problem that you have to deal with. I have been testing it on my 2019 Sr+ at a 90% charge which gives me an estimated 195 miles of range.

The wife makes a weekly trip to Indiana which round trip is about 110 miles. Using A Better Route Planner, with a 90% charge and my car data populated, ABRP estimated that she'd arrive back with a 22% charge. She arrived with 12% remaining.

What ABRP can't predict is it cabin temp being at 70 degrees. the seat warmer on and faster than normal driving.

I was told when I bought the car to expect about a 30% range loss in the winter and if you look at the numbers above, its about 31%.

 

[jjrandorin]

Hey, where can you check battery temperature? We're going on a long (600+ miles) trip Thursday, and have to leave at 6:30am, when it'll be right around freezing (32F). The high should hit around 65F. My first leg is 135 miles. I should be fine even with heat, and headwind with 90% charge, right? Will definitely heat the cabin and batteries from the app before leaving, probably like 5 to 10 minutes max, which should be enough, but will first start charging the car, so it doesn't suck juice from the batteries. I already tried doing that with car connected and not charging, and it does not suck juice from the wall until the battery drops a percent or two.

Finally, is there a way to heat the battery from the car? I don't like that the app heats both cabin and batteries when turning on 'climate'. It should have TWO separate buttons. You can see a small battery symbol with a snow symbol inside on the right top side of the app, but you can't 'unclick' it, or turn it off. You have to turn climate off. And if you preheat the battery like that, will it stay hot, or cool down, making the waste of energy useless? We'll hit highway speeds about 2 miles from my house.

There is no way without third party tools to measure battery temperature. This OP is using a third party ODB device that requires both an app, and physical connection to the car. scan my tesla

There is no way to heat the battery from the car, other than selecting a supercharger as the destination in the navigation system.

(edit: on model 3)

 

[JCtx]

Thank you very much guys; all is clear now. Will recheck ABRP with 240kWh, since my current average of 265 does not reflect highway driving at 80+. And I also used 15C (can't find how to change to F), when it'll be 0C when we leave, so will put 0. And finally, ABRP doesn't say how much the 'included driver' figure is (I'm 165#), but will assume it's the same, and put 200 more for my 130-lb wife plus luggage. First leg is only 135 miles, but need to decide if 90% is enough, or I need 95, just in case of headwind, etc. Thanks again for all the great help.

 

[jjrandorin]

Thank you very much guys; all is clear now. Will recheck ABRP with 240kWh, since my current average of 265 does not reflect highway driving at 80+. And I also used 15C (can't find how to change to F), when it'll be 0C when we leave, so will put 0. And finally, ABRP doesn't say how much the 'included driver' figure is (I'm 165#), but will assume it's the same, and put 200 more for my 130-lb wife plus luggage. First leg is only 135 miles, but need to decide if 90% is enough, or I need 95, just in case of headwind, etc. Thanks again for all the great help.

Since you are going on a trip, and have home charging, you should just charge to 100% before you leave. As long as the car doesnt sit for days at 100% its fine to charge to that percentage, and leave for your trip a within a few hours.

 

[Gasaraki]

30% is what i'm seeing. Of course the lost might be better if you cut down on your driving speed.