Winter city vs highway range loss question

[daemonic3]

Hey all, question for the experienced owners that have been through a winter.

We've got the expected range loss and GOM predicts from around 250-260mi (extrapolated to 10%) for about the last month. During summer we were roughly 300mi (except when my wife has done a recent freeway trip!).

Anyway, charged to 100% for a trip to Santa Cruz to get my daughter, the GOM started with 260mi. I did not precondition, and temp was roughly 55-60F, so mild but not what most would call "cold".

My results? I averaged ~60mph, achieved 3.4mi/kWh, drove 169 *actual* miles and only lost 145 *guess-o-meter* miles.

The question is: Is this typical that once you are on the freeway the battery naturally self-heats and you end up getting the optimum summer-type results versus short trips in the city where it either never has time or uses battery to warm itself causing the typical winter results?

I'm hoping that this is good news and will be repeatable, it helps for expectations and planning where to stop when we do a trip to SoCal for christmas.

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[KrazyEd]

There will be many factors. Speed, climate settings, terrain and weather conditions.
If it is sunny and car was sitting out before driving off you may not be using much A/C or heat.
I drive a taxi in Vegas and often use A/C when it is 60 degrees or heat when it is close to 70.
Over 15K miles on my 2021 Premium I averaged 5.2 miles per KWH. This included about 20%
highway miles. Plus two(ish) winters and a summer in Vegas.

 

[Mach-Lee]

Yes, the battery will heat up a little bit from use while driving, but not more than 10-20ºF or so. If the battery is above 32ºF it will not be heated at all. So it will not reach the optimum 70+ºF temp during winter. Also, the air is more dense in the cold, so range will be reduced even if the battery is very warm.

There is no way to escape some range loss in the cold, it's just physics. You're in Sacramento which doesn't really get colder than 40ºF, so your winter range will probably be in the 200-240 mi area.

Consider yourself lucky, I'm seeing less than 2.0 mi/kWh in the northern cold here.

 

[daemonic3]

Thanks team. I'm pleasantly shocked at the performance so I'm really trying to find if this will be repeatable. I should have run Carscanner to check battery temp as well. Missed opportunity! I know my F150 likes to lock in the battery temp right at 95F and must run a tight heat/cool PID loop because it doesn't deviate from it much. I assumed the MME would be similar and should have checked that.

Congrats on the 5.2mi/kWh that is INSANE! ?

I *hope* we don't dip into the 200-240 range at 100%! The wife enjoys the hell out of her car and uses all the heat and acceleration she wants like a madman, so I'm happy to get a GOM of 250. We drove to play pickleball and it was ~35 degrees a few times and I'm sure that is getting reflected nicely in our GOM rating!

 

[Mach-Lee]

Thanks team. I'm pleasantly shocked at the performance so I'm really trying to find if this will be repeatable. I should have run Carscanner to check battery temp as well. Missed opportunity! I know my F150 likes to lock in the battery temp right at 95F and must run a tight heat/cool PID loop because it doesn't deviate from it much. I assumed the MME would be similar and should have checked that.

Battery likes to be kept in the range of 32-95ºF. If it was hot outside then you'd see it cooled to 95ºF. Or if DCFC it likes 95ºF. Hybrids are much harder on the battery, drawing a much larger current relative to the battery size (C rate), so they heat up a lot more than a BEV battery under use.

Another tip I have for you is to just ignore the GOM in the winter. I only look at the %, keep it between 15-90%. If I'm worried about making it, slow down 10 MPH and lower the heat 5ºF (and keep fan speed low).

 

[Guss-E 2021]

Battery likes to be kept in the range of 32-95ºF. If it was hot outside then you'd see it cooled to 95ºF. Or if DCFC it likes 95ºF. Hybrids are much harder on the battery, drawing a much larger current relative to the battery size (C rate), so they heat up a lot more than a BEV battery under use.

Another tip I have for you is to just ignore the GOM in the winter. I only look at the %, keep it between 15-90%. If I'm worried about making it, slow down 10 MPH and lower the heat 5ºF (and keep fan speed low).

This. My first NH winter and I'm already finding things very easy to manage. Of course my drives are super short relative to my available range but I've still been experimenting with efficiency based on tips in the forum.

Side note: Aluminum batteries are showing real promise and are not affected by winter temperatures. The future looks bright.

 

[RickMachE]

Last winter we took a trip in 20 degree weather. Battery temp heated up to 90-95 while DCFC, dropped to 40-45 while driving. 2.3 vs 3.0 miles per kilowatt.

Edit - further info reviewing notes. Battery was often at 45 degrees while driving, sometimes got up to 60s. Air temp never got out of low 30s on entire trip, legs were 2.3, 2.6, 2.4, 2.5, 2.3, 2.4. In warm weather, these legs come in at 2.9, 3.0.

 

[timbop]

The range loss is not uniform in winter. It takes time and energy to warm the car and the battery up, so the beginning of your drive will generally see a bigger hit than the end of the drive. If you take a long drive you amortize that early peak over a larger time. If you only drive short distances then you will always be in the first part of the curve, so your range loss will be more significant. This is why preconditioning on grid power (and parking in a heated garage) is so important, although it cannot eliminate the loss of efficiency due to the cold temperatures as the battery will still be relatively cold compared to summer temperatures.

 

[sotek2345]

You are still seeing very mild temperatures, but I will say that I see more cold weather range reduction in local driving than on the highway. This is because the faster you go, the more miles your heating energy use is spread out over.

Here is a (bit of an exteme) example for illustration. Let's say your vehicle is using 6kW for heating.

If you are driving 6mph, that mean that you are using a full 1 kWh for heating for each mile you drive.

At 30mph, you are using 0.2 kWh for heating per mile

At 60mph, you are down to using 0.1 kWh for heating per mile.

 

[daemonic3]

Last winter we took a trip in 20 degree weather. Battery temp heated up to 90-95 while DCFC, dropped to 40-45 while driving. 2.3 vs 3.0 miles per kilowatt.

Edit - further info reviewing notes. Battery was often at 45 degrees while driving, sometimes got up to 60s. Air temp never got out of low 30s on entire trip, legs were 2.3, 2.6, 2.4, 2.5, 2.3, 2.4. In warm weather, these legs come in at 2.9, 3.0.

Very good info. Since my battery couldn't physically be lower temp than the ambient air, it sounds like I was likely still in the optimal range (15-35C, or 59-95F) and therefore not suffering winter range. The only range loss would likely be due to eHeat and I was fine with a jacket and seat on setting 1/3, with no eHeat.

The battery being roughly ambient+15F or more in Michigan weather is a good takeaway from this. I'll probably rarely suffer here in Cali on long drives if that's the case (other than eHeat).

You are still seeing very mild temperatures, but I will say that I see more cold weather range reduction in local driving than on the highway. This is because the faster you go, the more miles your heating energy use is spread out over.

Here is a (bit of an exteme) example for illustration. Let's say your vehicle is using 6kW for heating.

If you are driving 6mph, that mean that you are using a full 1 kWh for heating for each mile you drive.

At 30mph, you are using 0.2 kWh for heating per mile

At 60mph, you are down to using 0.1 kWh for heating per mile.

Exactly! Hence my original question regarding short city trips and highway longer (amortized) trips + self heating.

I'll check my battery temp next time to see what the self heat factor is when ambient is in the low 50s. I bet its enough to get me into the optimal range.

 

[sotek2345]

Very good info. Since my battery couldn't physically be lower temp than the ambient air, it sounds like I was likely still in the optimal range (15-35C, or 59-95F) and therefore not suffering winter range. The only range loss would likely be due to eHeat and I was fine with a jacket and seat on setting 1/3, with no eHeat.

The battery being roughly ambient+15F or more in Michigan weather is a good takeaway from this. I'll probably rarely suffer here in Cali on long drives if that's the case (other than eHeat).



Exactly! Hence my original question regarding short city trips and highway longer (amortized) trips + self heating.

I'll check my battery temp next time to see what the self heat factor is when ambient is in the low 50s. I bet its enough to get me into the optimal range.

For real world data, I saw as low as 1.4mi /kWh in local driving last winter, but highway trips (with pre-conditioning) were usually around 2.2. Both in sub-freezing temps.

 

[Maquis]

FWIW, battery capacity vs temperature is a curve. There is not an ”optimal band” where capacity is unaffected.

This a typical Li-ion curve, not specifically the MME battery.

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