Battery went from 7% to 0 and left me stranded 6 miles from charger.

[YellowstoneLightning]

Oh wow, so it's not just OP who's had this issue.

Now I'm curious and maybe @MickeyAO can chime in here to tell me whether I'm on the right track or totally off base, but I wonder if it has something to do with never charging to 100% for a true top balance. In theory, this could lead to a deviating BMS state of charge reading whose accuracy or lack thereof will be most pronounced at the extreme top or bottom of the battery state of charge.

How often do you charge to 100%?

I have only charged to 100 3 or 4 times since I got the truck last November.

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[Newton]

So you would agree that at any

The public SoC is heading from 100% to 0% once 131kWh (of the 143kwH) have been consumed.

FORD doesn't tell us what the reserves are, but based on 96% internal when public SoC is 100%, in an ER, it looks like they reserve about 6kWh at the top and 6kWh at the bottom. This let's us use 131kWh out of the total 143kWh.

So at 0% public SoC, the internal charge is still 4% (the reserve).

That is an interesting theory about how they maintain the high and low reserves, but there are a number of issues that it doesn't explain.

• On my SR, the internally reported kWh to empty is never over 95 kWh even after a 100% charge
• I have observed the internal battery percentage to decline by a significant amount after charging while the reported battery percentage remains the same
• Multiple reports show that there is pretty clearly no usable range below 0%
• If my data matched your graph, using my reported kWh as the x axis, I should be able to recreate the known 98kWh battery size and the unknown larger size at any point by dividing the reported kWh by the percentage We should see a nearly level line. Let's see how it goes:

 

[Grumpy2]

That is an interesting theory about how they maintain the high and low reserves, but there are a number of issues that it doesn't explain.

Is it possible the battery needs time to "settle" down to a stable voltage before each reading?

You have alot of scatter in your readings.

 

[lightspeed]

So you would agree that at any


That is an interesting theory about how they maintain the high and low reserves, but there are a number of issues that it doesn't explain.

• On my SR, the internally reported kWh to empty is never over 95 kWh even after a 100% charge
• I have observed the internal battery percentage to decline by a significant amount after charging while the reported battery percentage remains the same
• Multiple reports show that there is pretty clearly no usable range below 0%
• If my data matched your graph, using my reported kWh as the x axis, I should be able to recreate the known 98kWh battery size and the unknown larger size at any point by dividing the reported kWh by the percentage We should see a nearly level line. Let's see how it goes:

I'm not sure what the graph is trying to show.

The SR battery is 107.6kWh. It's clearly labeled on the battery. Of which 98kWh is usable according to Ford.

Again, we don't really know how they apportion the reserve but we know it's a 9.6kWh buffer which is probably split between high and low charge states.

95kWh max might be normal as a 3% loss in battery capacity sounds reasonable.

I'm sure that the "no usable range" below 0% is just how the software/BMS is programmed in order to protect the battery. In reality, there is probably 4kWh left. They have to set a hard stop somewhere.

 

[Barrels]

I didn’t know about that. Thanks for the tip. I’ll definitely (hopefully not have to) use that next time!

I believe Ford will reimburse you $140 if you didnt know about Ford Roadside assistance and got towed. See: https://www.ford.com/support/how-to...electric-vehicle-battery-roadside-assistance/

 

[YellowstoneLightning]

I believe Ford will reimburse you $140 if you didnt know about Ford Roadside assistance and got towed. See: https://www.ford.com/support/how-to...electric-vehicle-battery-roadside-assistance/

That’s super helpful, thank you!

 

[Ry2023]

Man you have me worried now … I have a 2500 mile round trip coming up later this year lol . I have personally never taken mine below 15 percent ….. but now I will definitely try to keep it above atleast that …I will definitely be interested in what the dealer has to say about what is causing this …..or what the remedy is…..

 

[AZT9]

Man you have me worried now … I have a 2500 mile round trip coming up later this year lol . I have personally never taken mine below 15 percent ….. but now I will definitely try to keep it above atleast that …I will definitely be interested in what the dealer has to say about what is causing this …..or what the remedy is…..

No Sweat. You will be good! I’ve driven on 800 miles family trips several times. Heck my drive to work is 205miles one way. She has 54k miles on her and she’s never done this before and hasn’t since. Truly the operator error. Stick to 10% bottom and I wouldn’t sweat it! Happy Travels

 

[Bpmiller]

On a road trip to New Mexico, driving from Pueblo, CO to Wagon Mound, NM, all was going great. There was a brisk head wind so my efficiency was pretty bad, but by all indications I was going to make it to my charger with some range to spare. Then, all of a sudden, at 7% battery with 6 miles to the charger, the battery dropped to 0% and we were stranded. Had to call a tow truck which took over two hours and cost $250 to take us to the charger. I’m quite confused as to why the SOC dropped as if the BMS had been wrong. Any thoughts/ideas would be appreciated. Thanks!

This one kept me up all night and without a truck for the weekend...
We were towing a boat in the cold mountains and dropped from 8% to 4% to 0! We were towed on a flatbed with AAA ("Randy MacGyver Tow Truck Driver") to an Electrify America charging station, but it wouldn't take a charge. By then the battery was so dead we had to jump the 12v (there's a red tag in the door frame of the driver's side to release the hood. The 12v is behind the plastic panel nearest the cabin) to be able to put it into neutral. Ford assistance said the only option was to take it to the dealer. So another tow (with Ford Roadside Assistance by "Noe your friendly neighborhood tow truck driver") to Lithia Ford in Fresno. I got there Friday at 4:00, but didn't get the truck back until Tuesday !! The best I can tell is that all they did was plug it into a 220 outlet. They did not need to replace the 12v, it did not need to be reset, and did not require a level 2 charger. All things that were suggested before I got it to the dealership.
my takeaways
1. cold weather drastically reduces range
2. use "reset EV range" when doing something new
3. If it won't charge at a station, try a regular outlet before going any further

 

[spadesaspade]

A similar incident happened with me right after I finished charging at EA fast charger. I ended charge at 60% SOC. After driving for 2-3 minutes, the SOC dropped to 54% straight from 60%. It stayed that way and continued to fall at a steady normal rate after that with no issues. I completed 2 road trips with 800 miles and 1000 miles after that trip and have not seen the issue again. Charged at multiple Tesla superchargers with no issues. It's sporadic which makes me more worried, now that I'm reading the reports here. Going from 85 to 0 in minutes is scary. I will not let it drop below 10% now, I have done this multiple times now on long road trips lowest being 5% SOC.

 

[YellowstoneLightning]

Thanks, everyone, for all your insight and interest in this topic. I am hopefully wrapping up this thread with a happy note: Ford reached out after seeing this thread and after I answered many, many questions via email, I just received a check that fully reimbursed me for the tow. Good on them for trying to rectify an unfortunate situation. Hopefully new lightnings won’t have this problem!

 

[Randall Stephens]

Thanks, everyone, for all your insight and interest in this topic. I am hopefully wrapping up this thread with a happy note: Ford reached out after seeing this thread and after I answered many, many questions via email, I just received a check that fully reimbursed me for the tow. Good on them for trying to rectify an unfortunate situation. Hopefully new lightnings won’t have this problem!

Anything that you can share? I was definitely thinking of this thread when deciding on whether to stop and charge on my last trip or push the guess o meter.

 

[Grease Lightning]

deciding on whether to stop and charge on my last trip or push the guess o meter.

I would always stop and charge if you have the option.

@MickeyAO in his various threads has shared that the Lightning’s battery does not enjoy deep cycle charging and he alluded that for long term durability that staying in the double digits of SOC will add to the longevity.

So I would always error on the side of hitting that one last charger if my SOC is going below 15% and I had the option. At the lightning’s 170 kw boost for about 10 minutes, you can add 10% in less then a bathroom break and not stress your batteries as much and save that stress for when you have to, not just want to get home.

 

[YellowstoneLightning]

Anything that you can share? I was definitely thinking of this thread when deciding on whether to stop and charge on my last trip or push the guess o meter.

A few people mentioned a similar issue to mine, with a common but not ubiquitous factor of having done multiple fast charges in a day. Apparently the bms needs time to be sure about the SOC, so leaving a second or third charging session at 80% might not actually be 80%. I think the takeaway for me is to always take the chance to charge if I can reasonably do so. On this day, I could have made another charge stop, and I would have made my destination on time if I had.

 

[RickLightning]

This is a good reason to use Car Scanner and know the available energy. You would then see if it just disappears or not.

Not being able to drive under 10% reliably is a big issue. Having put on 30,000 Mach-E miles and 10,000 Lightning miles, I have frequently gone below 10% on a trip. On the Mach-E very low. It never did this.

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