Mach-Lee's Mach-E Cold Weather Testing [Taking Requests]

[Mach-Lee]

Figured I'd make this topic to share my cold weather testing data this winter. It's going to be below zero Fahrenheit here on several days this week, and I'm sure there will be much more this winter (lowest we get is about -25ºF). But I wanted to offer to test things that people are interested in with the cold weather and share the results. So if there's something you wanted me to test in cold weather, let me know and I'll see what I can do.

Index of Tests:

• No Preconditioning Trip (Part 1) - #1
• Short Notice Preconditioning - #46
• Cabin Warmup speed comparison - #56
• Preconditioning Trip (Part 2) - #76
• 120V Battery Heating - #99
• 120V Departure Time Preconditioning - #101
• Idle Reserve Capacity Test - #126
• 120V Charging/Heating Test - #128
• Turning off HVAC to Heat Battery - #134
• En-Route Battery Preconditioning for DCFC - #138
• Battery Heating Time Chart - #142
• Reflectix Panoramic Roof Insulation Test - #147
• Warmer En-Route Preconditioning Test - #160

Current conditions:

No Preconditioning Trip

Here's a trip I took last night to look at cabin temps. I started with a cold car in my garage, no preconditioning whatsoever. I drove a loop with mixed highway and interstate driving. 2022 ER AWD.

12/19 Trip Summary:
Outdoor temp: -2ºF/-19ºC
Wind: calm
Distance: 89.3 mi
Duration: 83 min
Displayed efficiency: 1.9 mi/kWh
Average speed: 65 MPH

Preconditioning:
NONE

Starting conditions:
Cabin temp: 29.3ºF
Battery temp: 30.2ºF
Displayed SoC: 70.5%
kWh to empty: 48.956

Ending conditions:
Cabin temp: 64.4ºF
Battery temp: 33.8ºF
Displayed SoC: 8.5%
kWh to empty: 8.226

Calculated stats:
Battery used: 62%
Energy used (BECM): 40.73 kWh (this is too low due to BMS drift)
Calculated efficiency: 2.20 mi/kWh (based on above)
Calculated efficiency: 1.85 mi/kWh (based on wall)
100% range at -2ºF: 144 miles (52% of EPA)
100% energy available: 78.6 kWh

Charge back energy:
53.3 kWh from wall
91.5% charging efficiency
48.8 kWh estimated to the pack

HVAC set to 68ºF AUTO 1

FYI my temperature sensor was placed on the passenger seat just under the headrest. It wasn't the best placement so it probably had a bit more thermal lag due to the seat in close proximity. So in reality the air temp was a bit warmer than the temp sensor showed. I will work on a better sensor solution for future drives.

Notes:

I drove an out and back leg from my home to the interstate, so there's a mix of highway and interstate driving. No wind, almost no traffic, perfect test conditions. Temps variable from -4º to 0ºF. BlueCruise at 75 MPH on the interstate.

The whole car/battery started at about 29ºF in my garage, I got in and drove with minimum idle time beforehand. Within several minutes the windows were already fogging up badly, I had to use MAX Defrost to clear them, which worked well. The initial humidity in the cabin was very high for some reason which caused fogging, even though I had dry feet and mats. Potentially there was some moisture in the A/C core that took about 30 minutes to purge. It took about 30 minutes before I felt "warm enough" while driving, the rest of the time I was slightly chilly but acceptable (wearing a jacket). Throughout the drive, the windows periodically fogged up a little bit for only a couple minutes at a time before clearing up. It was obvious the fresh air damper was opening and closing, when closed the fog would form very quickly. You can see the humidity spikes on the graph when the damper closed.

On the interstate the pack actually cooled down a few degrees to a low of 28.4ºF. Interestingly, the split between minimum cell temp and maximum cell temp increased with time. The coldest cell was 26.6º while the warmest was 39.2º, a difference of 12.6º. At the end of the drive I saw 32/50ºF, a difference of 18ºF or 10ºC.

Slowing down with 1PD I was shocked at how much regen the car allowed with a pack below 0ºC, I saw up to 75 kW. That's crazy high and really not good for the pack because of the lithium plating risk. The regen limit was adjusting with pack temp, but I'm very skeptical that this is an acceptable amount for pack longevity. Teslas will have almost no regen when the pack is below 0ºC but I was getting almost the full amount here. Maybe the battery engineers know something I don't, but this was my biggest concern/finding of the drive. The battery temp also rapidly increased after regen events, the cells don't want to accept all that power so a lot of it gets turned into heat. Regen is why the pack temps went up at the end of the drive.

The navigation said I wasn't going to make it back home and wanted to add a charging stop, but I made it back with 9%. I was targeting 10% arrival, so I was close. The recorded mileage was also slightly less than what Google Maps got, that's probably nominal. There is also an efficiency discrepancy with the "This Trip" screen for some reason. I get 2.2 mi/kWh from the raw battery data but the screen said my trip was 1.9 mi/kWh. Not sure what's up with that. The overall efficiency and range performance was about what I expect for these temps (getting about half of the EPA rated range). With a full battery my actual range would be less than 150 miles with the extended pack.

Findings:

• The heater was pegged at maximum output the entire drive (about 5.4 kW)
• The battery was never heated the entire drive
• The battery didn't really warm up while driving (except from regen), it actually got a couple degrees colder on the interstate.
• Regen limit with a freezing battery was astonishingly high at 75 kW!
• Significant cell temperature variations can occur in the pack after driving, this is also not very desirable.
• The HVAC system closes the fresh air damper periodically to increase heat, but the cabin humidity spikes and windows fog.
• Initial humidity in the car can be an issue, it took about 30 minutes for the cabin to dry out.
• Cabin temperature was very slow to rise, takes at least 30 minutes for the cabin to warm to an acceptable temperature with no preheat.
• The navigation estimate for arrival percentage is off, about 10% error in the conservative direction.
• The efficiency calculated by the trip computer does not match the energy used data from the pack (1.9 vs. 2.2 mi/kWh).
• The actual range and efficiency is about what I would expect in sub-zero temps.
• The trip mileage is slightly low compared to Google Maps.

Conclusions:

• The cabin heat is pretty much at its limit around 0ºF. Window fogging and cabin comfort will likely go downhill from here as it gets colder.
• Wet feet and/or snow on the floor mats will increase fogging considerably.
• The new HVAC calibration helps improve heat but is still a bit chilly when below 0ºF.
• Trying to use recirc is out of the question at these temps, the windows will fog up almost immediately.
• I'm very concerned about the regen limit being so high with a cold pack. This could permanently damage it. Tesla does not allow virtually any regen at the same battery temps. It should be limited to 20 kW or less with a freezing pack IMO.
• Preconditioning to warm up the battery is highly recommended to prevent pack damage during regen.
• The trip computer and navigation seem to contain moderate errors in the conservative direction.

I plan on repeating the same trip after Preconditioning to see the difference.

 

[21st Century Pony]

Figured I'd make this topic to share my cold weather testing data this winter. It's going to be below zero Fahrenheit here on several days this week, and I'm sure there will be much more this winter (lowest we get is about -25ºF). But I wanted to offer to test things that people are interested in with the cold weather and share the results. So if there's something you wanted me to test in cold weather, let me know and I'll see what I can do.

Here's a trip I took last night to look at cabin temps. I started with a cold car in my garage, no preconditioning whatsoever. I drove a loop with mixed highway and interstate driving. 2022 ER AWD.

12/19 Trip Summary:
Outdoor temp: -2ºF/-19ºC
Wind: calm
Distance: 90.3 mi
Duration: 83 min
Displayed efficiency: 1.9 mi/kWh
Average speed: 65 MPH

Starting conditions:
Cabin temp: 29.3ºF
Battery temp: 30.2ºF
Displayed SoC: 70.5%
kWh to empty: 48.956

Ending conditions:
Cabin temp: 64.4ºF
Battery temp: 33.8ºF
Displayed SoC: 8.5%
kWh to empty: 8.226

Calculated stats:
Battery used: 62%
Energy used: 40.73 kWh
Calculated efficiency: 2.2 mi/kWh
100% range at -2ºF: 146 miles (52.7% of EPA)
100% energy available: 65.7 kWh

HVAC set to 68ºF AUTO 1

FYI my temperature sensor was placed on the passenger seat just under the headrest. It wasn't the best placement so it probably had a bit more thermal lag due to the seat in close proximity. So in reality the air temp was a bit warmer than the temp sensor showed. I will work on a better sensor solution for future drives.

Notes:

I drove an out and back leg from my home to the interstate, so there's a mix of highway and interstate driving. No wind, almost no traffic, perfect test conditions. Temps variable from -4º to 0ºF. BlueCruise at 75 MPH on the interstate.

The whole car/battery started at about 29ºF in my garage, I got in and drove with minimum idle time beforehand. Within several minutes the windows were already fogging up badly, I had to use MAX Defrost to clear them, which worked well. The initial humidity in the cabin was very high for some reason which caused fogging, even though I had dry feet and mats. Potentially there was some moisture in the A/C core that took about 30 minutes to purge. It took about 30 minutes before I felt "warm enough" while driving, the rest of the time I was slightly chilly but acceptable (wearing a jacket). Throughout the drive, the windows periodically fogged up a little bit for only a couple minutes at a time before clearing up. It was obvious the fresh air damper was opening and closing, when closed the fog would form very quickly. You can see the humidity spikes on the graph when the damper closed.

On the interstate the pack actually cooled down a few degrees to a low of 28.4ºF. Interestingly, the split between minimum cell temp and maximum cell temp increased with time. The coldest cell was 26.6º while the warmest was 39.2º, a difference of 12.6º. At the end of the drive I saw 32/50ºF, a difference of 18ºF or 10ºC.

Slowing down with 1PD I was shocked at how much regen the car allowed with a pack below 0ºC, I saw up to 75 kW. That's crazy high and really not good for the pack because of the lithium plating risk. The regen limit was adjusting with pack temp, but I'm very skeptical that this is an acceptable amount for pack longevity. Teslas will have almost no regen when the pack is below 0ºC but I was getting almost the full amount here. Maybe the battery engineers know something I don't, but this was my biggest concern/finding of the drive. The battery temp also rapidly increased after regen events, the cells don't want to accept all that power so a lot of it gets turned into heat. Regen is why the pack temps went up at the end of the drive.

The navigation said I wasn't going to make it back home and wanted to add a charging stop, but I made it back with 9%. I was targeting 10% arrival, so I was close. The recorded mileage was also slightly less than what Google Maps got, that's probably nominal. There is also an efficiency discrepancy with the "This Trip" screen for some reason. I get 2.2 mi/kWh from the raw battery data but the screen said my trip was 1.9 mi/kWh. Not sure what's up with that. The overall efficiency and range performance was about what I expect for these temps (getting about half of the EPA rated range). With a full battery my actual range would be less than 150 miles with the extended pack.

Findings:

• The heater was pegged at maximum output the entire drive (about 5.4 kW)
• The battery was never heated the entire drive
• The battery didn't really warm up while driving (except from regen), it actually got a couple degrees colder on the interstate.
• Regen limit with a freezing battery was astonishingly high at 75 kW!
• Significant cell temperature variations can occur in the pack after driving, this is also not very desirable.
• The HVAC system closes the fresh air damper periodically to increase heat, but the cabin humidity spikes and windows fog.
• Initial humidity in the car can be an issue, it took about 30 minutes for the cabin to dry out.
• Cabin temperature was very slow to rise, takes at least 30 minutes for the cabin to warm to an acceptable temperature with no preheat.
• The navigation estimate for arrival percentage is off, about 10% error in the conservative direction.
• The efficiency calculated by the trip computer does not match the energy used data from the pack (1.9 vs. 2.2 mi/kWh).
• The actual range and efficiency is about what I would expect in sub-zero temps.
• The trip mileage is slightly low compared to Google Maps.

Conclusions:

• The cabin heat is pretty much at its limit around 0ºF. Window fogging and cabin comfort will likely go downhill from here as it gets colder.
• Wet feet and/or snow on the floor mats will increase fogging considerably.
• The new HVAC calibration helps improve heat but is still a bit chilly when below 0ºF.
• Trying to use recirc is out of the question at these temps, the windows will fog up almost immediately.
• I'm very concerned about the regen limit being so high with a cold pack. This could permanently damage it. Tesla does not allow virtually any regen at the same battery temps. It should be limited to 20 kW or less with a freezing pack IMO.
• Preconditioning to warm up the battery is highly recommended to prevent pack damage during regen.
• The trip computer and navigation seem to contain moderate errors in the conservative direction.

I plan on repeating the same trip after Preconditioning to see the difference.

This is a pretty informative write-up. Thank You Mach-Lee.

 

[HGxxx]

From your data looks like a good idea to precondition just because of the Regen issue while near freezing temps? I don't know even if 10-15 min of preconditioning will help?

 

[johnmark]

Nice! Looking forward to the update.

Edit: when you precondition I'm very curious what the starting vs ending temp of the battery will be. I have to say I'm a little shocked there's no pack warming when driving. I guess it's to conserve energy.

 

[Mach-Lee]

Nice! Looking forward to the update.

Edit: when you precondition I'm very curious what the starting vs ending temp of the battery will be. I have to say I'm a little shocked there's no pack warming when driving. I guess it's to conserve energy.

I think it will heat it to about 15°C/59°F from past experience, but I’ll log it.

The heater isn’t big enough to also heat the pack while driving. 100% is going to the cabin with no heat to spare.

 

[awp0]

This is very interesting data, and thank you for providing it!

Question: Does anyone know the max regen rate (in kW) that you could expect if you use the lowest regen drive mode settings (Whisper with 1PD off)? I understand the brakes still use some regen, but it's unclear how much. I'm interested to know if you could still damage a cold battery even if you configure a "safe" drive mode.

 

[RedRocker]

Nice write up. I wonder why the humidity levels were so high early on, would have thought humidity would be low being so cold. Only thing I can think of is if the car was cold then brought into a warmer garage when parked prior to this and condensation formed on the colder surfaces?

Also surprised to see the temp delta between cells, would have thought they'd be much closer as they are probably all in a common cooling loop.

Appreciate the observations, interesting data.

 

[johnmark]

I think it will heat it to about 15°C/59°F from past experience, but I’ll log it.

The heater isn’t big enough to also heat the pack while driving. 100% is going to the cabin with no heat to spare.

Thanks - that would explain why turning off the cabin heat makes a big difference in energy consumption. I think I'm just going to bundle up when driving lol

 

[RedRocker]

This is very interesting data, and thank you for providing it!

Question: Does anyone know the max regen rate (in kW) that you could expect if you use the lowest regen drive mode settings (Whisper with 1PD off)? I understand the brakes still use some regen, but it's unclear how much. I'm interested to know if you could still damage a cold battery even if you configure a "safe" drive mode.

Pretty sure the regen limits are the same, that is why the modes are considered the same for range. The difference is in how you achieve the regen 1PD captures a lot of regen when you lift-off, the other modes capture regen when you lift-off/apply brakes. Its all about vehicle decel rate, drive smoother and your peak regen will be less regardless of mode.

 

[Nklem]

Figured I'd make this topic to share my cold weather testing data this winter. It's going to be below zero Fahrenheit here on several days this week, and I'm sure there will be much more this winter (lowest we get is about -25ºF). But I wanted to offer to test things that people are interested in with the cold weather and share the results. So if there's something you wanted me to test in cold weather, let me know and I'll see what I can do.

Current conditions:

Here's a trip I took last night to look at cabin temps. I started with a cold car in my garage, no preconditioning whatsoever. I drove a loop with mixed highway and interstate driving. 2022 ER AWD.

12/19 Trip Summary:
Outdoor temp: -2ºF/-19ºC
Wind: calm
Distance: 90.3 mi
Duration: 83 min
Displayed efficiency: 1.9 mi/kWh
Average speed: 65 MPH

Starting conditions:
Cabin temp: 29.3ºF
Battery temp: 30.2ºF
Displayed SoC: 70.5%
kWh to empty: 48.956

Ending conditions:
Cabin temp: 64.4ºF
Battery temp: 33.8ºF
Displayed SoC: 8.5%
kWh to empty: 8.226

Calculated stats:
Battery used: 62%
Energy used: 40.73 kWh
Calculated efficiency: 2.2 mi/kWh
100% range at -2ºF: 146 miles (52.7% of EPA)
100% energy available: 65.7 kWh

HVAC set to 68ºF AUTO 1

FYI my temperature sensor was placed on the passenger seat just under the headrest. It wasn't the best placement so it probably had a bit more thermal lag due to the seat in close proximity. So in reality the air temp was a bit warmer than the temp sensor showed. I will work on a better sensor solution for future drives.

Notes:

I drove an out and back leg from my home to the interstate, so there's a mix of highway and interstate driving. No wind, almost no traffic, perfect test conditions. Temps variable from -4º to 0ºF. BlueCruise at 75 MPH on the interstate.

The whole car/battery started at about 29ºF in my garage, I got in and drove with minimum idle time beforehand. Within several minutes the windows were already fogging up badly, I had to use MAX Defrost to clear them, which worked well. The initial humidity in the cabin was very high for some reason which caused fogging, even though I had dry feet and mats. Potentially there was some moisture in the A/C core that took about 30 minutes to purge. It took about 30 minutes before I felt "warm enough" while driving, the rest of the time I was slightly chilly but acceptable (wearing a jacket). Throughout the drive, the windows periodically fogged up a little bit for only a couple minutes at a time before clearing up. It was obvious the fresh air damper was opening and closing, when closed the fog would form very quickly. You can see the humidity spikes on the graph when the damper closed.

On the interstate the pack actually cooled down a few degrees to a low of 28.4ºF. Interestingly, the split between minimum cell temp and maximum cell temp increased with time. The coldest cell was 26.6º while the warmest was 39.2º, a difference of 12.6º. At the end of the drive I saw 32/50ºF, a difference of 18ºF or 10ºC.

Slowing down with 1PD I was shocked at how much regen the car allowed with a pack below 0ºC, I saw up to 75 kW. That's crazy high and really not good for the pack because of the lithium plating risk. The regen limit was adjusting with pack temp, but I'm very skeptical that this is an acceptable amount for pack longevity. Teslas will have almost no regen when the pack is below 0ºC but I was getting almost the full amount here. Maybe the battery engineers know something I don't, but this was my biggest concern/finding of the drive. The battery temp also rapidly increased after regen events, the cells don't want to accept all that power so a lot of it gets turned into heat. Regen is why the pack temps went up at the end of the drive.

The navigation said I wasn't going to make it back home and wanted to add a charging stop, but I made it back with 9%. I was targeting 10% arrival, so I was close. The recorded mileage was also slightly less than what Google Maps got, that's probably nominal. There is also an efficiency discrepancy with the "This Trip" screen for some reason. I get 2.2 mi/kWh from the raw battery data but the screen said my trip was 1.9 mi/kWh. Not sure what's up with that. The overall efficiency and range performance was about what I expect for these temps (getting about half of the EPA rated range). With a full battery my actual range would be less than 150 miles with the extended pack.

Findings:

• The heater was pegged at maximum output the entire drive (about 5.4 kW)
• The battery was never heated the entire drive
• The battery didn't really warm up while driving (except from regen), it actually got a couple degrees colder on the interstate.
• Regen limit with a freezing battery was astonishingly high at 75 kW!
• Significant cell temperature variations can occur in the pack after driving, this is also not very desirable.
• The HVAC system closes the fresh air damper periodically to increase heat, but the cabin humidity spikes and windows fog.
• Initial humidity in the car can be an issue, it took about 30 minutes for the cabin to dry out.
• Cabin temperature was very slow to rise, takes at least 30 minutes for the cabin to warm to an acceptable temperature with no preheat.
• The navigation estimate for arrival percentage is off, about 10% error in the conservative direction.
• The efficiency calculated by the trip computer does not match the energy used data from the pack (1.9 vs. 2.2 mi/kWh).
• The actual range and efficiency is about what I would expect in sub-zero temps.
• The trip mileage is slightly low compared to Google Maps.

Conclusions:

• The cabin heat is pretty much at its limit around 0ºF. Window fogging and cabin comfort will likely go downhill from here as it gets colder.
• Wet feet and/or snow on the floor mats will increase fogging considerably.
• The new HVAC calibration helps improve heat but is still a bit chilly when below 0ºF.
• Trying to use recirc is out of the question at these temps, the windows will fog up almost immediately.
• I'm very concerned about the regen limit being so high with a cold pack. This could permanently damage it. Tesla does not allow virtually any regen at the same battery temps. It should be limited to 20 kW or less with a freezing pack IMO.
• Preconditioning to warm up the battery is highly recommended to prevent pack damage during regen.
• The trip computer and navigation seem to contain moderate errors in the conservative direction.

I plan on repeating the same trip after Preconditioning to see the difference.

I would love to see real charge data used. Calculations based on battery percentage or even using the BMS data were always off from that data. I will say, I think your 157 miles is spot on for a preconditioned battery and matches my data from last winter. If you did not precondition, that would have been 120-130 miles of range. If you could and test again, simply recharge to 100% after driving (starting at 100%) and calculate real efficiency based on Real miles driven to real kWh re-charged. You may be surprised it does not match the mi/kWh display, even after you deduct the 10% for charger losses. I think you may see that mi/kWh is actually about 15% less. Now, my data was measured in early 2022 on July 2021 software. I know Ford did some corrections and updates since I departed from my Mach E ownership, so that 1.9 mi/kWH may be spot on now (2.2*.85-1.9) but I would love to see a test on a 2022. You can only tell by charging back to 100% and reading what your charger puts back into the battery and deduct the 10% for losses. If you can do this and report back, that would be awesome and close a lot of questions. You may end up with the same result which will go along way in validating the BMS.

I found measuring and validating the Mach E performance a lot of fun. Since my charging power was free from work, I did not care about efficiency...but it was a blast to validate and learn how the BMS worked. Carscanner is a great engineering tool. .......Great post.....

 

[sockmeister]

This data makes me wonder if there *is* a real benefit to actual preconditioning for daily use, even if you're not going on a long trip -- if simply because heating the battery makes regen charging a little safer for its long-term health.

 

[Blackpony]

How do you get battery temperature readings? Do you have to plug into the car's data port? It isn't available on the information screen right

 

[RickMachE]

How do you get battery temperature readings? Do you have to plug into the car's data port? It isn't available on the information screen right

Right.

OBD2 adapter and Car Scanner app.

 

[johnmark]

This data makes me wonder if there *is* a real benefit to actual preconditioning for daily use, even if you're not going on a long trip -- if simply because heating the battery makes regen charging a little safer for its long-term health.

Exactly what I was wondering.

 

[Nklem]

This data makes me wonder if there *is* a real benefit to actual preconditioning for daily use, even if you're not going on a long trip -- if simply because heating the battery makes regen charging a little safer for its long-term health.

Preconditioning and night heating consumes about 4.5 kWh per my testing. So if you gain 130-157 miles of range (highway), that’s 27/4.5 or 6 Mi/kWh or more. To me it’s worth it….. in warmer conditions, 10F or better and non highway the gain can be 10 mi/kWh as a 26F battery can get 170-190 miles of range. But it all depends on your commute distance and what you pay for power.

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