Battery Coolant/Heat strategy needs work!

DaMeatMan

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Today was -22 in Toronto, Canada and I just wanted to share a few observations about the coolant/heat loop for cabin heating as well as battery temp maintenance.

First off when charging the vehicle at a DC Fast Charger when cold the Mach-E will either heat the pack, or heat the cabin, but NOT both.

Essentially if cabin heat is turned off and you start to DC Fast charge you will hear the Mach-E turn on the coolant/heating loop for the battery pack, it sounds like a slight hum along with the occasional gurgling sound. If you watch the coolant heat energy consumption with car scanner or something similar you can see that it will start using about 6KW to heat the fluid going to the battery, and the battery temp will slowly start to go up.

The second you turn on cabin heat, you can hear the coolant loop to the battery shut down, and whatever heat is generated by the PTC heater is used exclusively for heating the cabin. If you sit long enough and watch the HVB battery temp, you can see it slowly start to drop.

In BOTH cases at a 50KW charger i watched the charger charge at around 30KW. If I was on a much higher powered charger I suppose I could sit there and wait 30 min with cabin heat off so that the battery temp can get warm enough to start ramping up the speed of the charger, however doing so would essentially mean freezing inside the car.

I decided to try this for a while and prioritize heating of the battery for a while just to observe the behavior further, and by the time the pack got warm enough to exceed 30KW I had hit the 80% cliff. But I decided to let it prioritize battery heating, and i sat even longer with cabin heat off. Eventually I noticed that the power being drawn from the charger was only slightly higher than the power being drawn from the PTC heater, and the charge rate of the high voltage battery had pretty much stalled out. The overall charge rate was about 7KW while the PTC heater was drawing about 6KW, which meant the pack was receiving about 1KW or less on a high powered DC Charger???

The interesting thing was that by turning on the cabin heat, i saw that the car had immediately started requesting more power from the charger about 12KW, and I immediately noticed the charge rate on the HVB start to climb with PTC heater receiving about 4KW - 6KW, while the pack received the rest 6KW - 8KW. Which completely surprised me because this is counter to what you would expect to actually see, since the whole reason for freezing to death in the cabin is to allow the heating loop to warm the pack, and the reason for wanting to warn the pack is to get a faster state of charge. With that said, it seems the vehicle charging algorithm was not smart enough to know to request max power at the cliff (12kw) and instead ramped down power until battery heating power consumption and requested power were almost identical, which means the charge algorithm was treating a DC Fast charge session as if it were plugged into AC and just maintaining pack temperature while not really charging at all!

When you think about it, that logic is beyond absurd, and I could have been sitting at a DC Charger all day long and not really increased charge rate much beyond 90% which is insane! For thus experiment I purposely chose a free charger, otherwise this would have been an insanely expensive charge session that was essentially just keeping my battery warm!

Now I know there is an update that changes the charge curve after 80%, but I'm wondering if anyone who has it and also lives in cold weather can confirm if it improves the charge rate when cabin heat is off, and you are sitting in the cold passed 90%?

In any case Ford has allot of work to do here, primarily in sharing that coolant loop (if it is physically possible), hopefully it is because with only one PTC heat source it sounds pretty absurd to make the customer chose between freezing, or heating a pack. When you also consider that it takes aproximately 20 - 30 min to make an appreciable difference in pack temperature when in really cold weather, and the Mach-E is not smart enough (yet) to start preconditioning and warming the pack ahead of time when setting a charger as the GPS destination, then it really leaves allot to be desired, and is an incredibly inefficient use of resources with a tremendous amount of plugged in charge time used just trying to get up to ideal temperatures. When you consider that most people would not sit around longer than 30 min anyway, then the heating strategy seems like a completely moot point, and very poorly executed from a Software and hardware engineering perspective.

What are your thoughts and observations?

 

RickMachE

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Can't answer your question, but the update does say "improved range in cold weather" and "DC fast charge total time improvements".

We all believe the 2nd item refers to changing the dropoff from 80% to 90%, but no one has said they know what the first one means.

I think everyone agrees that there needs to be an update to pre-condition the battery for high speed charging, both driven by the navigation seeing the charger is coming soon, as well as triggered manually by the driver.

Ford has recommended to turn off the e-heat when you're charging. Using the heated seat should be enough for that period of time.
 

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I think it is fascinating that you can hear the battery coolant loop shutting down. Do you actually hear the fluid circulating through the battery pack while sitting in the car?

I can sometimes hear the pump running while the car is charging on L2 but usually only when the shutters are open. If it's cool enough then they remain closed (after a quick function test) and in those cases I have to place my hand on the RH front fender to feel the pump circulating fluid.

One of my goals when I get time it to remove the trunk tub and plastic covers above and below and then figure out a way to actuate all the cooling loops and valves in order to see exactly how things function. The WSM is helpful but leaves a lot to be desired still.
 
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DaMeatMan

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I think it is fascinating that you can hear the battery coolant loop shutting down. Do you actually hear the fluid circulating through the battery pack while sitting in the car?

I can sometimes hear the pump running while the car is charging on L2 but usually only when the shutters are open. If it's cool enough then they remain closed (after a quick function test) and in those cases I have to place my hand on the RH front fender to feel the pump circulating fluid.

One of my goals when I get time it to remove the trunk tub and plastic covers above and below and then figure out a way to actuate all the cooling loops and valves in order to see exactly how things function. The WSM is helpful but leaves a lot to be desired still.
Yes I can hear the slight humm, as well as what sounds like the very muffled and quiet draining of fluid into the fill container as well as the occasional gurgle. Although the gurgle sounds are most predominant right after shutting down, assuming because there is air in the system that escapes out into the container after circulation stops.
 


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I've said it before but the mach E is a terrible winter car not driving wise but in the other ways that count. If your main source of charging is public charging I wouldn't recommend this vehicle to anyone that lives in a colder climate unless you want to deal with the headaches.
 

RickMachE

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This kind of "problem" is exactly why we didn't drive it to Florida in late December.
 

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I've said it before but the mach E is a terrible winter car not driving wise but in the other ways that count. If your main source of charging is public charging I wouldn't recommend this vehicle to anyone that lives in a colder climate unless you want to deal with the headaches.
Heck....I think the same is true for warmer climates as well. If your main source of charging is public facilities then the MME isn't the best choice.
 
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DaMeatMan

DaMeatMan

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I might have missed it in the Sandy Munroe teardown, but does anyone know if it's mechanically possible for the coolant loop to be used for BOTH cabin and battery at the same time? What I mean by this, is the physical valve mechanism either or? Or can it allow for both, but the limitations so far are poor software engineering design decisions?
 

SnBGC

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I might have missed it in the Sandy Munroe teardown, but does anyone know if it's mechanically possible for the coolant loop to be used for BOTH cabin and battery at the same time? What I mean by this, is the physical valve mechanism either or? Or can it allow for both, but the limitations so far are poor software engineering design decisions?
Yes it is possible.

1642280861227.png
 

Mopey

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I have been collecting cold weather observations from my FE in Fairbanks, Alaska. I was planning on saving them for an end of winter post, but since I've found similar results in severe cold, here is a DC Fast (50kw)charging summary from last week:

Charging without preheating:
What the car looked like an hour before the 1st charging on 4 Jan. It had been left at my office over the holidays. (BTW. It started and ran perfectly despite the temps)

Car Before Charginf.jpg

4 Jan -27F Charging without preheating, just the drive to the charger:
Note the -4F Battery Temp!

-30 Before Charging.jpg

-30 at End of Charging.jpg
Cold Battery Charger Readout.jpg


7 Jan -30F. Car had been preheated by the 32A charger at work first:
Before Plugin
-30 with Preheat Before Plugin.jpg

At End of Charge:
-30 with Preheat Mid Charge.jpg

Station During Charge
7 Jan Charger Readout.jpg


FLO Charging Summary:
FLO charges by the minute (which sucks). I ended up paying $1.35\kWh to get less than 2kW in 12 minutes without battery preheating and paid just $.37\kWh to get almost 8kW in about 14 minutes with battery preheating. If you compare to the start finish battery charge, you will see that most of the Kw purchased went to heating, not additional range.

Charge Cost.jpg


I'm just posting actual cold weather results here. You can draw your own conclusions as to how they might apply to you. Bottom line on charging (so far): Regardless of the limitations of the Mach E, as designed, it runs and charges just fine in extreme cold, if you follow the sage advice about plugging in and making use of departure scheduling to preheat.

Side Note: In addition to this post and my previously posted worst case range test, I am continuing to collect extreme cold observations and recommendations once I have a full winter of real world data from which to draw complete conclusions.
 
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breeves002

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So yes, when you put the cabin heater on it prioritizes heating the cabin but that does not mean it disables battery heating entirely. It will blend them but prioritizes maintaining cabin heat.
 

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So yes, when you put the cabin heater on it prioritizes heating the cabin but that does not mean it disables battery heating entirely. It will blend them but prioritizes maintaining cabin heat.
Agree.
It also sounds like while in Combined Loop mode, and E-Heat turned off then by default all the heat will end up going towards the battery pack vs the cabin. Probably flows through the heater core but since the blend doors are closed then no air is passing over the core so that heat is retained in the fluid and then exchanges in the HVB pack. Sound about right?
 

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Ford has recommended to turn off the e-heat when you're charging. Using the heated seat should be enough for that period of time.
Not very helpful if you're on a road trip with rear seat passengers. If they're going to recommend using heated seats in the winter, they need to add them to the rear seats and make them standard on all models (at least they added front to Rt1 for '22).
 

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I have been collecting cold weather observations from my FE in Fairbanks, Alaska.....

-30 Before Charging.jpg
John,

Excellent info thank you! I thought that 17F in Maryland this morning was bad!! May I ask what software and hardware you are using to capture this information? Looks somewhat like Torque Pro on Android? Thanks!

 

 
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