Mach E Range dropped drastically while parked

[Ames8705]

Hi - Recently my Mach E dropped from an estimated range of 80 miles to 20 miles while parked for an hour. At both ranges the car said there was 40% battery life remaining. It was probably in the 30s outside, a bit colder with wind chill. However, I've parked my car outside for days in colder temperature and never experienced a drop like that. I had it towed to a dealer as I couldn't find a fast charger and I thought something was wrong with the car. The dealer claims there is nothing wrong with it because they cannot replicate the issue and there were no software codes. The dealer believes it is just the fact that the range drops in the cold. I am well aware that the range drops in the cold - as I had been getting closer to 170 at 100% rather than the 240 I'll get in the summer. Additionally, I've noticed when I drive it in the cold sometimes the range will drop by more than the miles - i.e., (drops 25 miles on a 12 mile ride). However, I have never had it drop while parked and turned off in the cold. In the 9 months I have had the car, I have noticed 2 other occasions where the range dropped significantly (never as low as 20) while parked. I believe once there was an electrical error sign on the dash but I can't remember what it was called. Both times when I charged it the range got back up to more normal levels. Has anyone else experienced this issue?

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[Mach-Lee]

If you have a LFP battery, when’s the last time you charged it to 100%?

 

[Ames8705]

I can't recall - likely in the last month.

 

[Mach-Lee]

I can't recall - likely in the last month.

OK, the LFP battery needs to be charged to 100% overnight with a Level 2 charger at least once a month to maintain accuracy of the range meter. Otherwise you will see large range drops like you’re experiencing. I recommend charging to 100% every week with a LFP pack.

If you charge to 100% and the issue is fixed, then you know what it was.

 

[MadMatt]

OK, the LFP battery needs to be charged to 100% overnight with a Level 2 charger at least once a month to maintain accuracy of the range meter. Otherwise you will see large range drops like you’re experiencing. I recommend charging to 100% every week with a LFP pack.

If you charge to 100% and the issue is fixed, then you know what it was.

on this point, there's no danger of say not doing that 100% weekly though right? other than a very inaccurate GOM?

 

[Mach-Lee]

on this point, there's no danger of say not doing that 100% weekly though right? other than a very inaccurate GOM?

No danger other than the GOM being inaccurate and running out of charge way sooner than expected.

 

[MachE70]

No danger other than the GOM being inaccurate and running out of charge way sooner than expected.

Do we know if an inaccurate GOM tends to overestimate the range remaining, meaning you will run out of charge way sooner than expected as you note above? Or is an inaccurate GOM just as likely to underestimate the range remaining? I have a '22 GT that I generally keep between 30 and 70% SOC and only rarely charge to 100%.

 

[RickMachE]

Do we know if an inaccurate GOM tends to overestimate the range remaining, meaning you will run out of charge way sooner than expected as you note above? Or is an inaccurate GOM just as likely to underestimate the range remaining? I have a '22 GT that I generally keep between 30 and 70% SOC and only rarely charge to 100%.

And you don't have the LFP battery...

 

[MachE70]

And you don't have the LFP battery...

True, but my NMC battery also has the same issue of GOM inaccuracy due to lack of BMS calibration. In fact, I am charging to 100% right now following @Mach-Lee's BMS calibration procedure. My question still remains, do we know if GOM inaccuracy tends to overestimate or underestimate remaining range? Is the answer different for LFP vs NMC batteries?

 

[Mach-Lee]

True, but my NMC battery also has the same issue of GOM inaccuracy due to lack of BMS calibration. In fact, I am charging to 100% right now following @Mach-Lee's BMS calibration procedure. My question still remains, do we know if GOM inaccuracy tends to overestimate or underestimate remaining range? Is the answer different for LFP vs NMC batteries?

It can do both. But you'll never hear about the cases it underestimates range (car goes further than stated). People will only complain if it overestimates range and they come up short.

In winter it's more common to have overestimates than underestimates. Flip in the summer.

NCM is generally within 5% accurate, but LFP could be off by 40% because of the flat voltage curve, so it's a bigger concern.

 

[MachE70]

It can do both. But you'll never hear about the cases it underestimates range (car goes further than stated). People will only complain if it overestimates range and they come up short.

In winter it's more common to have overestimates than underestimates. Flip in the summer.

NCM is generally within 5% accurate, but LFP could be off by 40% because of the flat voltage curve, so it's a bigger concern.

Good to know, thanks.

 

[Ames8705]

OK, the LFP battery needs to be charged to 100% overnight with a Level 2 charger at least once a month to maintain accuracy of the range meter. Otherwise you will see large range drops like you’re experiencing. I recommend charging to 100% every week with a LFP pack.

If you charge to 100% and the issue is fixed, then you know what it was.

Thanks... so I understand what you're saying about charging the car and accuracy of range. But are you saying that the inaccurate range would cause the car to drop from 80 miles to 20 miles remaining while parked? In other words, that the range was showing an overage of 60 miles which got corrected while parked? Just trying to make sure I understand.

 

[Mach-Lee]

But are you saying that the inaccurate range would cause the car to drop from 80 miles to 20 miles remaining while parked? In other words, that the range was showing an overage of 60 miles which got corrected while parked?

Yes. The range can suddenly correct when there a high degree of BMS error, or conditions change since the last drive. The SoC is sensed and updated when the vehicle has been shut off and sitting for a while.

The battery didn't actually lose any energy. The computer guesstimate of how much energy was left simply changed.

 

[steveg95]

OK, the LFP battery needs to be charged to 100% overnight with a Level 2 charger at least once a month to maintain accuracy of the range meter. Otherwise you will see large range drops like you’re experiencing. I recommend charging to 100% every week with a LFP pack.

If you charge to 100% and the issue is fixed, then you know what it was.

What is the "LFP" battery?

 

[RickMachE]

What is the "LFP" battery?

Starting in late 2023, Ford introduced a different battery for standard range vehicles. LFP, or Lithium Iron Phosphate versus the existing NCM or Nickle Cobalt Manganese. LFP is cheaper to make, so it saves Ford money. LFP has lower energy density, so they need to be bigger (and heavier) than a comparably sized NCM battery. LFPs can be charged to 100% often, whereas NCMs should not be. LFPs are good for those in warm climates, as in winter they really take a hit as compared to NCMs.

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