Preparation needed for extreme cold weather

[Mach-Lee]

That certainly would not make sense either. My question is more to the point of why <25 degrees is the trigger point? Why not 30 or 40? And I wonder what it actually heats too?

When the battery temperature dips below freezing, it will be warmed up to 41°F. The strategy keeps the battery temperature just above freezing, which is the minimum acceptable operating temperature of a lithium battery. They set the temperature that low to minimize the amount of energy used to maintain the battery temperature. Maintaining the battery at 77°F would waste dramatically more energy.

If your garage is above freezing, then the battery will not need to heat itself because it’s not cold enough. But I still recommend using a departure time to get extra temperature into the battery because it will be lost rapidly once you start driving in the cold.

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[dalola]

When the battery temperature dips below freezing, it will be warmed up to 41°F. The strategy keeps the battery temperature just above freezing, which is the minimum acceptable operating temperature of a lithium battery. They set the temperature that low to minimize the amount of energy used to maintain the battery temperature. Maintaining the battery at 77°F would waste dramatically more energy.

If your garage is above freezing, then the battery will not need to heat itself because it’s not cold enough. But I still recommend using a departure time to get extra temperature into the battery because it will be lost rapidly once you start driving in the cold.

Yes, I understand the theories, I'm just curious about the numbers... Heating starts at 25, and warms to 41? Seems odd, but I'll assume Ford did extensive testing to determine the optimum trigger temps. lol... dangerous assumption! ?

So what is the process of events when the car is sitting in a parking lot all day, unplugged, it's about 10 degrees, and you get in to drive home?

 

[Peugfan]

So what is the process of events when the car is sitting in a parking lot all day, unplugged, it's about 10 degrees, and you get in to drive home?

Your car still starts and runs but range takes a bigger hit. Your battery is less efficient, and since the car prioritizes the battery, your 5kw heater may give you only modest cabin heat. I've done cold starts at less than 0 F and I still got enough heat to be comfortable. Try taking a few cold start trips of 4 miles or less with no preconditioning. The GOM will panic and the indicated range plummets. ?

 

[hypersnake]

Your car still starts and runs but range takes a bigger hit. Your battery is less efficient, and since the car prioritizes the battery, your 5kw heater may give you only modest cabin heat. I've done cold starts at less than 0 F and I still got enough heat to be comfortable. Try taking a few cold start trips of 4 miles or less with no preconditioning. The GOM will panic and the indicated range plummets. ?

This is my experience as well. I usually park my car at home in the garage and plug it in at night. I have only slightly negligible range when the battery is preconditioned on the plug for my commute in the negative degree weather this morning.

Yesterday when I left my car outside at work in 10 degree weather, there was a noticable drop when I had to go out on a cold start. I had about a quarter of jail bars and the GOM was in the tank.

Preconditioning off battery helps, but it then uses a couple percentage of battery to get to that point.

It goes back to the basic ABCs - Always Be Charging.

 

[pepiopee]

It goes back to the basic ABCs - Always Be Charging.

Always Be Charging... Doesn't this have a negative side effect though? I would almost always be at my target charge of 80% instead of cycling through 80 -> ~40 -> 80, etc.

 

[hypersnake]

Always Be Charging... Doesn't this have a negative side effect though? I would almost always be at my target charge of 80% instead of cycling through 80 -> ~40 -> 80, etc.

As far as we know, no.

 

[South Side]

I think that plug in message was removed at some point, don't know why. With Ford, you never know.

Hmm, I just received that message today when I got home.

 

[MellowJohnny]

Perhaps orthogonal to the main question, but if you are out and about make sure you have all the Apps you may need to charge. I stopped yesterday to charge in -14c temps and helped a guy in a GT charge at a DCFC for the first time. I said "You picked a hell of a day to mess around with a new charging App..."

 

[Rory]

Yes, I understand the theories, I'm just curious about the numbers... Heating starts at 25, and warms to 41? Seems odd, but I'll assume Ford did extensive testing to determine the optimum trigger temps. lol... dangerous assumption! ?

So what is the process of events when the car is sitting in a parking lot all day, unplugged, it's about 10 degrees, and you get in to drive home?

I betcha they started warming at -5 C and stopped at +5 C. +5 is 41 F. -5 is about 23.

 

[Snakebitten]

This is the first day that my Mach-E would have ever experienced true winter frosty temps. And it's very unlikely after this white stuff melts tomorrow afternoon, it will never have snow on it again. It just doesn't snow here.

Anyways, I decided that after it had sat all day frozen, that I'd at least throw it on the L2 charger and set it up for a 10:am departure tomorrow morning in hopes of pumping some heat into its battery.

Since the SOC was 81% and my target SOC is 85%, as soon as I plugged the Emporium in, it started a 6.2KW charge session with an estimate of reaching the target SOC at 11:03 pm.

Sure enough, the Emporium app confirmed that what FordPass was reporting is in fact what the EVSE was doing.

It's 21F and when the car reached 84% SOC, FordPass reported that it no longer was charging, but rather it switched to "Preparing Cabin and Battery for departure"

Note that 84% is just short of 85, AND it's 11 hours before departure!

I checked the EVSE, and sure enough it was pumping out 6.7KW (28A/240).

So my question is, because the battery was so cold-soaked, and the car is plugged in, is the BMS heating up the HVB even though technically it has ample time before it had to before 10:am?

Also note, about 45 minutes of drawing current for "Preparing Cabin and battery for departure", FordPass switched back to Charging mode, but erroneously stated the target was 100%. However, it stopped charging five minutes later after hitting the real target of 85%

It's so cold outside that I'm not going out there to do an OBD check on the battery temperature, but I believe the battery was in fact being warmed and the GOM increased as a result.

But it was interesting to see the BMS and thermal management switch from charging the battery, to heating the battery, and then back to finishing the charge session.

As interesting as it was though, I'm ready to put this frosty weather EV strategy behind me. I'll take my normal tropical winter over this icy insanity. Everything is just too much work. Even opening the door to move the car to the EVSE....... I had to use the forward camera to navigate because the wipers were frozen in windshield ice/snow. The charge port was frozen shut. The door extender needed my tug on the handle to break the door free.

You northerners have some grit!

 

[dalola]

This is the first day that my Mach-E would have ever experienced true winter frosty temps. And it's very unlikely after this white stuff melts tomorrow afternoon, it will never have snow on it again. It just doesn't snow here.

Might be time to ban BEV's, as they have clearly reversed global warming, and are causing the next ice age.... ? Think I'll go burn some trash to help heat up the atmosphere again....

 

[Snakebitten]

It's proof that my Mach-E is my beater.

The big macho 4WD F150 is nestled safely in the barn out of the weather. ??

 

[Mach-Lee]

This is the first day that my Mach-E would have ever experienced true winter frosty temps. And it's very unlikely after this white stuff melts tomorrow afternoon, it will never have snow on it again. It just doesn't snow here.

Anyways, I decided that after it had sat all day frozen, that I'd at least throw it on the L2 charger and set it up for a 10:am departure tomorrow morning in hopes of pumping some heat into its battery.

Since the SOC was 81% and my target SOC is 85%, as soon as I plugged the Emporium in, it started a 6.2KW charge session with an estimate of reaching the target SOC at 11:03 pm.

Sure enough, the Emporium app confirmed that what FordPass was reporting is in fact what the EVSE was doing.

It's 21F and when the car reached 84% SOC, FordPass reported that it no longer was charging, but rather it switched to "Preparing Cabin and Battery for departure"

Note that 84% is just short of 85, AND it's 11 hours before departure!

I checked the EVSE, and sure enough it was pumping out 6.7KW (28A/240).

So my question is, because the battery was so cold-soaked, and the car is plugged in, is the BMS heating up the HVB even though technically it has ample time before it had to before 10:am?

Also note, about 45 minutes of drawing current for "Preparing Cabin and battery for departure", FordPass switched back to Charging mode, but erroneously stated the target was 100%. However, it stopped charging five minutes later after hitting the real target of 85%

It's so cold outside that I'm not going out there to do an OBD check on the battery temperature, but I believe the battery was in fact being warmed and the GOM increased as a result.

But it was interesting to see the BMS and thermal management switch from charging the battery, to heating the battery, and then back to finishing the charge session.

As interesting as it was though, I'm ready to put this frosty weather EV strategy behind me. I'll take my normal tropical winter over this icy insanity. Everything is just too much work. Even opening the door to move the car to the EVSE....... I had to use the forward camera to navigate because the wipers were frozen in windshield ice/snow. The charge port was frozen shut. The door extender needed my tug on the handle to break the door free.

You northerners have some grit!

Yes that's normal battery heating. You've probably never seen that before outside of departure times. I have a hair dryer for when things get frozen shut. You need to run remote start to defrost things before you try to move the car if it snowed. We also like to park in garages instead of outside for obvious reasons.

It was -20ºF yesterday so 21ºF isn't bad.

 

[Snakebitten]

Thanks for the info Mach-Lee!

To complete my ONE AND ONLY experience as a Mach-E owner in sub-freezing temps, this morning the BMS apparently kicked off yet another battery warming session before it was time for the "departure pre-conditioning" routine. It appears to have lasted about 40 minutes of shore power.

Then, at about 1 hour before the scheduled departure, the typical pre-conditioning started up. Once I got in the car, even though it was still covered in snow, the wipers were able to make their sweep and the ice layer was no longer stuck to the glass.
The car was so nice inside and the GOM had gotten back about 35 miles of the 50 miles reduction for 85% SOC.

Also note the battery was at 66F. That's awesome, in my opinion. No bars and the car only used 1% more SOC to travel the 24 miles to work than it normally does in 70F weather.

I know this car gets bashed a lot for not having the latest and greatest EV technology. But I'm still very pleased with what it's capable of if you are well aware of how to manage its native abilities.

If I ever did live in real winter climates, I would definitely move my EVSE into the barn and always have the Mach-E plugged in at night. I'm fortunate to live in normally tropical climate, and I'm now aware of how less vigilant I have to be regarding SOC and thermal management.

 

[dalola]

Also note the battery was at 66F.

Why would it be 66 degrees? I thought it was already determined that it would heat to 41?

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