Only 138 miles range at 84%

[Nklem]

I'm afraid GOM's calculations are closer to reality than yours.
The efficiency (2.4mi/kWh) is measured based on real miles and real power consumption, not the battery capacity. The battery capacity in low temps is significantly lower than the nominal 88kWh, according to GOM it's about 68kWh.
There is only way to know the exact range is to drive from full to empty.

I do not know if I follow you here. Yes the battery capacity may be somewhat reduced (when the battery is extremely cold and not actively heated, but the battery is heated by the climate system when driving to make sure it has ample capacity most of the time. If you plug in and precondition, before departing, keeping it warm, I dare say you have 88 KWh to start or close most of the time. I did a test (while sick in bed from my Booster shot, Yuk). It was 55 degrees when I felt great and I left my Mach E at 75% unplugged for 36 hours. It cooled to 30 degrees the next day and last night/this AM was 24 degrees. This AM I still had the same range and the same 75% battery capacity. If the GOM was taking into account the ambient temps adjusting for battery capacity loss, I would assume it would have lost range.

I still do not trust the GOM at all in cold weather yet and it seems very pessimistic, I believe, to protect the driver from ending up stranded. But I did some more calculations to verify below.

Some real numbers from that 18F Trip which was at an average speed of 60.5 MPH and interior climate at 70F. What I have determined is the GOM is about 5-10% off from reality. I drove 113.4 miles starting at 93% (81.8 KWh, preconditioned) battery and ending at 29% (25.5 Kwh). So I used 56.3 KW for the trip and overall real mi/kWh of 2.01. The efficiency calculation in the car reported 2.3 Mi/kW. When I departed, the GOM reported 161 Miles of range @93%, which would be 173 at 100%. In reality from this trip, it was actually 2.01*88=177 Miles, so a 4% GOM error. (but that was actually based on past driving , not this trip) At the end, (29%) the GOM reported 46 miles of Range, which in reality was 2.01*25.5 kWh=51.3 miles (10% GOM error). Now 93% can be 92.5% to 93.4% and 29% can be 28.5% to 29.4%. So assuming the best, that could be 55.5 KWh or 2.04 mi/kWh a range of 2.04*88=180 miles at 18F, highway speed of 60.5 MPH.

So we can assume the car was either off by 0.3Mi/kWh in efficiency calculations reported OR the battery capacity was reduced due to the cold weather by 11 kWh (12.6% capacity loss, 2.01/2.3) at 18F.

I will do some additional testing when it gets super cold (10F or so) and see what the next batch of calculations comes out to. I also have an OBD tool and EV software so I may be able to get the real battery kWh numbers so I can fine tune this next one. That will tell us if there is any loss of battery kWh or the cars efficiency calculation is off. I hopefully can do this with preconditioning and without. So Stand by for more.....

I will certainly try a full to empty test as well, as you noted.

Owning an EV is so much fun for an Engineer.

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[Murse-In-Airy]

Owning an EV is so much fun for an Engineer.

Or just an middle aged guy who likes numbers and is trying to prevent cognitive decline of aging.

 

[Murse-In-Airy]

Reset your range/trip meters and ease up on the pedal and heater. The number should begin to rise up a bit over a week or two.

Ahh. Yes. I should reset my range meter wiping out all knowledge the AI has from my past driving history and conditions. So instead of being off a little it can give totally made up numbers and be off A LOT. Sound advice.

 

[sockmeister]

I think a lot of readers didn't read your entire post.

 

[RedStallion]

I do not know if I follow you here. Yes the battery capacity may be somewhat reduced (when the battery is extremely cold and not actively heated, but the battery is heated by the climate system when driving to make sure it has ample capacity most of the time. If you plug in and precondition, before departing, keeping it warm, I dare say you have 88 KWh to start or close most of the time.

Capacity is being reduced as temperature drops, perhaps GOM accounts for that. There is a warming effect when the batteries warm themselves, but it's not sufficient to restore the full capacity in cold weather.
I don't have a discharge curve for MME battery, but all Li-Ion batteries look approximately the same. Here is one example I found

And as I mentioned the efficiency in mi/kWh is not adjusted by the change in battery capacity. It's measured, not guessed.

 

[Murse-In-Airy]

Capacity is being reduced as temperature drops, perhaps GOM accounts for that. There is a warming effect when the batteries warm themselves, but it's not sufficient to restore the full capacity in cold weather.
I don't have a discharge curve for MME battery, but all Li-Ion batteries look approximately the same. Here is one example I found

And as I mentioned the efficiency in mi/kWh is not adjusted by the change in battery capacity. It's measured, not guessed.

Thanks for the graphic @RedStallion. Now I get what you’re saying.

 

[Nklem]

Capacity is being reduced as temperature drops, perhaps GOM accounts for that. There is a warming effect when the batteries warm themselves, but it's not sufficient to restore the full capacity in cold weather.
I don't have a discharge curve for MME battery, but all Li-Ion batteries look approximately the same. Here is one example I found

And as I mentioned the efficiency in mi/kWh is not adjusted by the change in battery capacity. It's measured, not guessed.

Capacity is being reduced as temperature drops, perhaps GOM accounts for that. There is a warming effect when the batteries warm themselves, but it's not sufficient to restore the full capacity in cold weather.
I don't have a discharge curve for MME battery, but all Li-Ion batteries look approximately the same. Here is one example I found

thanks. The Mach E does use the electric resistance fluid heater to warm the battery in cold temps. I wish we had some real system tech specs so we could know how the battery does react to these temperatures and what it tries to Maintain. Without this info, we can only speculate. All I can find is

“The high-voltage battery system uses an advanced active liquid heating and cooling system to regulate high-voltage battery temperature and help maximize the performance of the high-voltage battery”

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