PSA: Keep The Battery Warm So You Have Enough Cabin Heat

[breeves002]

From this write-up, it seems obvious Ford did extreme cold testing, and that's why they have software to specifically make sure the battery gets priority over the cabin when you need heat.

And correctly so: I'd rather be rolling cold then stuck, and I'd rather be reliably rolling than stressing a part to failure, and it seems they part they put in gives enough oompf to keep you going, even if it's optimized for temps over 0 F

Yes I can agree with you that the software does treat things correctly. However with how much of the United States that experiences single digit or lower temperatures yearly how can you just say "oh sorry its 2ºF outside, you're going to have no cabin heat at all because we severely undersized the heater". Causing your windows to fog and you to be very cold. It's BS in this expensive car. My Rivian had no issues with highway driving at -4ºF yesterday. I left it outside for 9 hours overnight unplugged, drove 2 hours in the morning. Horrible economy but I stayed warm and the windows didn't fog up. The Mach E that wouldn't have happened.

Also just because the battery heat is prioritized doesn't mean much about cold weather testing. They knew the battery cells need to stay above x temp so that can be defined in software without ever testing it in the real world. I'm sure they did test it in the real world but you see my point.

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[bbulkow]

Yes I can agree with you that the software does treat things correctly. However with how much of the United States that experiences single digit or lower temperatures yearly how can you just say "oh sorry its 2ºF outside, you're going to have no cabin heat at all because we severely undersized the heater". Causing your windows to fog and you to be very cold. It's BS in this expensive car. My Rivian had no issues with highway driving at -4ºF yesterday. I left it outside for 9 hours overnight unplugged, drove 2 hours in the morning. Horrible economy but I stayed warm and the windows didn't fog up. The Mach E that wouldn't have happened.

Also just because the battery heat is prioritized doesn't mean much about cold weather testing. They knew the battery cells need to stay above x temp so that can be defined in software without ever testing it in the real world. I'm sure they did test it in the real world but you see my point.

'
I'm glad you see my point that a statement that Ford "clearly" didn't do cold weather testing was a bit rash. Neither of us know whether they did or not, but we know car companies do, and the fact that they put in a decent algorithm makes it more likely than not that they did. So we agree.

While I would be off looking up what percent of the population is effected by temperatures under 0 F how many days of the year, that's not really the point. Any of us might want to drive to wyoming. There's always a question of how extreme weather to design for. Why stop at 0 F, when the Canadians have -30 F? One does wonder how much extra it would have cost in parts for more heater. These kind of design choices have ripple effects sometimes - more wire here, bigger coolant or heater pipes there.

How much more expensive are the Rivians? 10%? 20%? I think it was 20% when I was talking to a Rivians owner and did the math, but it was back of the envelope. And we consider the MachE overpriced at this point.

But I"m with you in spirit - I'd certainly expect a car like this to behave better than you describe in 0 F (and lower) temps. Within the lifetime of this car we'll expect markedly lower lows, and higher highs - likely up to 150F surface temperatures in North America, I haven't seen projections for low temps over the next 10 years - so a forward thinking company would be folding that into designs.

 

[Stang Enthusiast]

The information provided within the thread provides good insight as to the causality for the cabin heat fluctuations and higher battery usage/drain while driving my 2021 MME GTPE. I live in Alaska where temperatures can and do have extended periods of subzero weather most recently -12 to -18 F. I know with ICE vehicles there are battery blankets that minimize the effects of cold on batteries. Just curious if this is a plausible solution to the battery temperature issues?

 

[dtbaker61]

Wanted to write a note about this since many people are currently experiencing extreme cold temps (below 5ºF/-15ºC). In a nutshell:

Keeping the battery is warm is important so you have enough cabin heat!

If the battery is cold, the Mach-E will steal your cabin heat to warm the battery. The heater is shared between the battery and cabin. Battery temp takes priority over cabin temp. As a result, if the battery is cold, you may be cold. You may notice inconsistent heat at different times. It's related to the battery temperature.

As a reminder, follow these tips:

• Plug in the car when it's below freezing as much as possible to keep the battery warm. Every night.
• Set a departure time before any trips longer than approximately 15 minutes (warms the battery up fully).
• Use a Level 2 charger instead of Level 1 (L1 doesn't provide enough heating power).
• Make sure your EVSE is set to allow charging anytime and your charging hours aren't overly restrictive (≥8 hours per day).
• If you can't plug in, then run a remote start for 10-15 minutes before leaving. It's much easier to warm the cabin up when the car is stationary vs. driving.
• LIMIT FAN SPEED to a medium level or less (≤3). High fan speeds actually cool down the cabin in extreme cold.
• Use a moderate heat setting of 65-72ºF (18-22ºC) to avoid excessive fan speed and energy loss. Turning it up hotter won't help.
• Park in a garage rather than outside. This can keep the battery a lot warmer.
• If possible, drive slower. This will reduce convective heat loss.

Owners are experiencing lack of heat when parking the vehicle outside unplugged, or when they have extremely restrictive charging hours that don't allow the battery to draw power to for heating. The EVSE must allow charging at the time you are performing a departure time, or it won't work.

If you have a time-of-use rate plan, you may need to allow some charging to occur during peak times so the battery can heat. The small added expense from this may be well worth having heat. I see about 3 kWh usage to complete a full departure time (typically costs <50¢/day). I would avoid the highest peak times, but if you have a mid-peak rate, that would be okay for preconditioning use because the usage will be small. In cold weather, I recommend setting a departure time at least once a day before the anticipated time of vehicle use (battery stays warm for hours afterwards). If you don't have a regular schedule, you can set a battery-only departure time to reduce energy use. For more information about how/when to set departure times, see my other topic: Mach-Lee's Cold Weather Charging Strategies

For example, I have my EVSE set to allow charging at any time 24/7 and my charging hours in the car are set from 10PM to 10AM. I would set it this way even if my rate plan ended at 6 AM. The car usually only charges a for a couple hours (always done before 6 AM), but can automatically heat itself if necessary up until 10 AM. Departure times will still work anytime because the EVSE allows charging.

The heater in the Mach-E is undersized for extreme cold (only 5 kW) and may not be able to keep the cabin fully warm in temps below 5ºF/-15ºC even after following all the tips. Dress warmly. The minimum operating temperature of the Mach-E is around -31ºF/-35ºC, you may have zero cabin heat available around that temp. If the battery gets too cold, you'll enter turtle mode and have almost no power (can't maintain speed). Full heater output will be diverted to the battery, but in extreme cold that might not even be enough.

Cold weather requires some changes when driving an EV. You're living plug-to-plug in the extreme cold, and the ability to draw Level 2 power for heating becomes critical.

if you don't have a warm garage, rather than leaving car plugged in all night radiating heat, you will use a little less energy if you plug in 15-20 minutes before you leave, and start the car.

If you are not home, then just remote-start the car and let it warm the battery for 10-30 minutes before departure. You might want to change your 'auto-off' setting to 30 minutes rather than the default 10 minutes. Very similar to what you might do with an ICE vehicle in extreme cold.

 

[ChasingCoral]

if you don't have a warm garage, rather than leaving car plugged in all night radiating heat, you will use a little less energy if you plug in 15-20 minutes before you leave, and start the car.

If you are not home, then just remote-start the car and let it warm the battery for 10-30 minutes before departure. You might want to change your 'auto-off' setting to 30 minutes rather than the default 10 minutes. Very similar to what you might do with an ICE vehicle in extreme cold.

Unfortunately, remote start warms the cabin but does not precondition the battery. To precondition the battery requires using a departure time setting.

 

[breeves002]

if you don't have a warm garage, rather than leaving car plugged in all night radiating heat, you will use a little less energy if you plug in 15-20 minutes before you leave, and start the car.

If you are not home, then just remote-start the car and let it warm the battery for 10-30 minutes before departure. You might want to change your 'auto-off' setting to 30 minutes rather than the default 10 minutes. Very similar to what you might do with an ICE vehicle in extreme cold.

15-20 minutes is not enough time to heat the battery in extreme cold.

You can’t remote start the car. That doesn’t heat the battery. You MUST set a departure time.

Auto-off is 30 mins only applies if you get in the car and start it manually. Remote start duration is max 15 minutes and can be extended to 30 once started.

 

[dtbaker61]

The information provided within the thread provides good insight as to the causality for the cabin heat fluctuations and higher battery usage/drain while driving my 2021 MME GTPE. I live in Alaska where temperatures can and do have extended periods of subzero weather most recently -12 to -18 F. I know with ICE vehicles there are battery blankets that minimize the effects of cold on batteries. Just curious if this is a plausible solution to the battery temperature issues?

the HV battery isn't really accessible to put a blanket on.....

what is 'best' of course is a heated garage. doesn't solve the problem when you're not home of course.

hhhhmmmmmm, what about a pop-up fabric tent. aluminized mylar lining to keep the heat in ?! set up the tent wherever you have to leave the car out in the cold, drive in, zip up, and cozy!

or..... a fabric 'skirt' all around, drops to the ground.... ya know like a mobile home to keep the cold air from freezing your important bits.

 

[dtbaker61]

Unfortunately, remote start warms the cabin but does not precondition the battery. To precondition the battery requires using a departure time setting.

ooooohhhhhhh THATS super good information! I was not aware of that.

THIS is what you'd have to do before leaving work for instance when the car has been outside all day.

 

[dtbaker61]

15-20 minutes is not enough time to heat the battery in extreme cold.

You can’t remote start the car. That doesn’t heat the battery. You MUST set a departure time.

Auto-off is 30 mins only applies if you get in the car and start it manually. Remote start duration is max 15 minutes and can be extended to 30 once started.

excellent info!
thats why I keep coming back to this group..... learn something every day.

Key takeaway is 'set departure time if car is <20F'

 

[ChasingCoral]

ooooohhhhhhh THATS super good information! I was not aware of that.

THIS is what you'd have to do before leaving work for instance when the car has been outside all day.

But only if you have an L2 charger at work. Battery preconditioning will only operate when plugged in. IIRC it will not precondition on L1 because there isn't enough power available.

 

[Tyldum]

I do want to add that my PTC was not providing stable cabin temps akin to OP description, however in my case the PTC was failing and was in the end replaced by the dealer even though Ford refused.

There is not DTC thrown, but there is a PID that initially indicated degraded PTC with about 2,5kW power draw and later was failed with 0kW.

Since being replaced I've had no issues with heat even at -15C. Preconditioned or not.

It was a bit of a fight, but data logging was very valuable (Torque with additional PIDs from this excellent forum).

 

[aberberich]

Finding this thread just now after having a pretty scary experience yesterday.

I went to ski at a resort an hour from my house. It was 1 degree F out with a windchill of -21. I charged the car to 100% and warmed it up before leaving. Arrived at the resort at 65% (had a seasucker ski rack mounted as well). Skied for 4 hours and then went home. While taking off my gear I ran the heat at full blast (it was still -21F windchill). The cabin warmed up enough during this time and off I went. The drive is mostly highway and I held 85MPH comfortably and safely. With the heat set to 85 Auto Speed 2. Around 45 minutes in I began to notice the heat was not as warm but really didn’t think much of it. Then suddenly I see a yellow turtle on my dash. As this happens the speed of the car begins to reduce (even though cruise is enabled and set to 85). Eventually it settles at 70MPH. Im only a few miles from my exit so I opt to just keep going vs pull over etc. Suddenly the turtle turns red and my speed drops again. The car is now struggling to hold 55 (in a 70 ?). Luckily I am only half a mile from my exit. Upon getting off and slowing down (thus engaging the regen) the turtle is gone. I safely drive the car home. It’s worth noting this all happened when I had 22% down to 18%. The battery was not even in single digits.

does anyone have advice on how to prevent this in the future? I plan to follow the advice of this thread however I don’t have a charger at the ski resort and I did drive home with the heat on auto 2. Perhaps next week I will turn the temperature down and try driving 75 instead of 85?

had the car 2 years now and have never had an issue like this, however it typically does not hit -20 windchill where I live. Usually a week of 0 or -5 at the lowest.

 

[curtisfinney]

Question about plugging in every night, this is going to top off battery. I have mine set to 80%. Does anyone know if this is a negative from a battery longevity standpoint?

 

[Tyldum]

Question about plugging in every night, this is going to top off battery. I have mine set to 80%. Does anyone know if this is a negative from a battery longevity standpoint?

Mine has been plugged in more or less daily since May 2021 and battery health was 99% last checked a couple of months ago. I have it at 90%.
Concencus seems to be that DCFC is what reduces the batteri longevity.

 

[Sam2084]

Finding this thread just now after having a pretty scary experience yesterday.

I went to ski at a resort an hour from my house. It was 1 degree F out with a windchill of -21. I charged the car to 100% and warmed it up before leaving. Arrived at the resort at 65% (had a seasucker ski rack mounted as well). Skied for 4 hours and then went home. While taking off my gear I ran the heat at full blast (it was still -21F windchill). The cabin warmed up enough during this time and off I went. The drive is mostly highway and I held 85MPH comfortably and safely. With the heat set to 85 Auto Speed 2. Around 45 minutes in I began to notice the heat was not as warm but really didn’t think much of it. Then suddenly I see a yellow turtle on my dash. As this happens the speed of the car begins to reduce (even though cruise is enabled and set to 85). Eventually it settles at 70MPH. Im only a few miles from my exit so I opt to just keep going vs pull over etc. Suddenly the turtle turns red and my speed drops again. The car is now struggling to hold 55 (in a 70 ?). Luckily I am only half a mile from my exit. Upon getting off and slowing down (thus engaging the regen) the turtle is gone. I safely drive the car home. It’s worth noting this all happened when I had 22% down to 18%. The battery was not even in single digits.

does anyone have advice on how to prevent this in the future? I plan to follow the advice of this thread however I don’t have a charger at the ski resort and I did drive home with the heat on auto 2. Perhaps next week I will turn the temperature down and try driving 75 instead of 85?

had the car 2 years now and have never had an issue like this, however it typically does not hit -20 windchill where I live. Usually a week of 0 or -5 at the lowest.

I had basically the problem, Saturday but I got the orange turtle at 30% HVB while driving 70 mph heat set to 65F. I had to pull off the interstate and take backroads for the last 10miles of my trip. Its absolutely ridiculous how underpowered the heater is.

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