Got to 2%, 5 miles to go - then I experienced something I didnt

[Rocket808]

TLDR: as stated in other threads - 0% is 0 power left. But the power for propulsion actually drops to zero before that from around 2%. It appears to cycle down and up.
Recommendation: don’t push it below 10 miles of range remaining according to GOM.
——-

I knew as my SOC reduced, the max power decreases from 100

I did a local trip last night, basically picking a relative off from airport and dropping them off and heading home, I decided to try to get home with approximately 1 mile range - so I did a very small amount extra driving to be as close as possible.

I pulled up to a stoplight at 2% charge, and when it turned green, I had zero throttle response. Available Power on the dial showed 3 (maybe lower?) but no reaction from the truck. I had cars behind me so hit the throttle a few times. They went around. I snapped a photo at 3% power, yet with 2% charge (and 5 miles).

I was on a flat road and it was nearly all downhill (very slight grade) to go from my location - was about a mile away from my house.

I did begin to freak out a bit having the “I can’t believe I just ran outta battery” feeling - no difference in running out of gas feeling. All the inside electrical was still 100% normal and turned on my hazards.

I power cycled the car, though I don’t know if that did anything.

I watched the power bar cycle back up to 38% and the light cycled back to green again and I was able to continue on. I became extremely cautious now as I had an instance of no power at all.

got home with 1 mile range! I don’t need to do this experiment again.

The ICE cars gurgle and spit when they are at their last drops of gas. Our EVs just stay silent!

 

[evowner]

I was was getting that feeling in my stomach as I was reading your story. I made it back with an EV6 that showed 3 when I pulled up to my shop. Mine was not an experiment.

 

[Danface]

Ouch, glad you made it home and thanks for the cautionary tale and "workaround"

QUESTION: I heard that if the truck "goes to 0" then you can only charge on an L2 charger, not a DCFC charger, is this true? (I rather not find out first hand).

 

[rockhead]

I read one guy who limped 20 kms after hitting zero, clearly YMMV

 

[Pioneer74]

I read one guy who limped 20 kms after hitting zero, clearly YMMV

I would only do that in emergencies. Any buffer close to 0 isn't guaranteed. In fact, I believe Kyle had to push his truck a couple of times to a charger on his race with Tom, and he still had a few percent showing.

Also, if the Lightning is programmed anything like the Mach-E, the 12V battery isn't maintained once the HV battery is below 20%. If you have a lot of accessories on, you could very well lose enough charge in the 12V battery to strand yourself.

 

[bmwhitetx]

I power cycled the car, though I don’t know if that did anything.

IIRC others have mentioned that turning the vehicle completely off for x minutes allowed a certain amount of recovery that let them go again.

 

[George D]

Shortly after getting our Lightning and doing our first road trip, she asked me if we needed to stop to charge. I said "We probably have enough charge."
Her reply was spot on. "Probably enough is not enough"
So we stopped to charge.

 

[Danface]

Shortly after getting our Lightning and doing our first road trip, she asked me if we needed to stop to charge. I said "We probably have enough charge."
Her reply was spot on. "Probably enough is not enough"
So we stopped to charge.

Obviously, she's a keeper!

 

[Smokey]

An EV with 0 % can be charged with a DCFC. The vehicle's battery and charging management system will charge the depleted batteries. Taking batteries to 0 charge is stressful on them and will shorten their life span overtime. Batteries can "recover" some charge when left off after being discharged, much like a flashlight that will work for a minute the next day.

 

[Danface]

An EV with 0 % can be charged with a DCFC. The vehicle's battery and charging management system will charge the depleted batteries. Taking batteries to 0 charge is stressful on them and will shorten their life span overtime. Batteries can "recover" some charge when left off after being discharged, much like a flashlight that will work for a minute the next day.

Thanks for the info. I haven't done that and try to plan well enough to reduce the likelihood of it happening ... On this front, I'm aiming for 100!

 

[Adventureboy]

Taking batteries to 0 charge is stressful on them and will shorten their life span overtime.

^^^^. This is the key here. Anything into single digits of your SOC is aging your battery much faster than the 20-90% range. While you won't notice the range hit for a while, it will add up over time if you do this regularly. Keep it above 10% to keep your battery's SOH in good condition. It is especially hard on the cells if you give it 10 minutes and then push it again.

 

[Ry2023]

what is your charging pattern if you don’t mind me asking ? I know that if you do a lot of DC fast charging i.e. on a long road trip the BCM can get out of whack and the percentages be off a little bit…( such as what happened to the out of spec guys on the EA race) … not sure if it also happens for those who do not charge often… I noticed my percentage hopping up and down after mine sitting for a few days…. I usually don’t plug in till I’m about below 50% ? And I wonder if level two charging to a high state of charge balance is the cells…. And helps recalibrate the bcm?

 

[Zprime29]

^^^^. This is the key here. Anything into single digits of your SOC is aging your battery much faster than the 20-90% range. While you won't notice the range hit for a while, it will add up over time if you do this regularly. Keep it above 10% to keep your battery's SOH in good condition. It is especially hard on the cells if you give it 10 minutes and then push it again.

I seem to recall MickeyAO said below 20% for our batteries showed a significant increase in degradation. Or at least, that's how I interpreted his post. He's a little on the cryptic side sometimes I've only let mine go under 20% a small handful of times on road trips. I think the lowest I've been is 13%. Haven't checked my battery health in a while but at 2 years old I see very little change to my daily commute.

 

[Adventureboy]

I seem to recall MickeyAO said below 20% for our batteries showed a significant increase in degradation. Or at least, that's how I interpreted his post. He's a little on the cryptic side sometimes I've only let mine go under 20% a small handful of times on road trips. I think the lowest I've been is 13%. Haven't checked my battery health in a while but at 2 years old I see very little change to my daily commute.

Ford reserves the bottom part of the battery, so 10% SOC on the gauge has some buffer still. 20% is better. MickeyAO knows his stuff.

I keep mine between 20-85% most of the time. Charge to 100% once per month or so. Ocassionally have dipped into 10-20% range and only a couple times below 10% into high single digits. Just over 2 years and SOH is still 100% for me.

 

[hturnerfamily]

early on, I had a similar instance, yet my last 200 yards was up a steep 25% grade to my son's home, and my 'charging' outlet...

I arrived at the start of his road with 2%, and maybe 3 'miles of range' showing(although we all now know that this is not to be relied upon)... as a precaution to 'running out' before getting to the top of his ridge, I decided to use the good ol' GUN IT and HOPE FOR THE BEST approach... letting inertia and momentum carry my new truck to the 'top'...

well, that's not how it works with EVs:

the truck came to an almost dead stop when I slammed my foot on the 'gas'... I knew nothing of the 'power' gauge, as that had never been something I was concerned about, or, frankly, even KNEW about. It immediately decided that, no, it was NOT going to keep going, especially if this darn 'driver' was going to punch the pedal....

When the truck stopped, I was dumbfounded, and yes, like most anyone, 'assumed' I had actually ran out of 'power'... I was now in a pickle. In the skinny rural road, going uphill, with no options... or so I initially thought. It was also late at night. One of my other sons was with me.

I sat and thought for a moment. Well, I might as well try to 'slink' back down the hill, if possible, and leave the truck on the side of the MAIN road, where I could then have some time, and room, to think. I knew that even anyone with a generator would not really be an option, no more than a VERY long extension cord from a home 100 yards away.

I put the truck in NEUTRAL, having figured that this was my only option: The truck slipped down slowly, while my son stood near the back just to make sure I was staying on the roadway - the dark of night didn't help, and the road was also not 'straight'...

just then, I saw the start of a driveway on one side, and immediately decided to back 'into' the upward driveway, and let the momentum and grade then allow me to turn the truck back FORWARD, to go the rest of the way to the main road. It worked, and I was able to let the grade, and gravity, let the truck slide down onto the side of the main roadway, in the grass.

Just as I came to a final stop, I realized that I probably had gone a little too far, so, without thinking, and just with instinct, I put the gear shift into REVERSE and, voila!, I had REVERSE POWER... what!!???

at that moment, knowing little to nothing about whether the truck would also go into FORWARD power, and not wanting to chance it, I left my son on the side of the roadway, and IMMEDIATELY backed up the WHOLE ROAD TO MY SON'S HOUSE... all the way, all the way up the 25% grade, and not really even slowly, either - the truck HAD POWER.
Later, my son finally got to the top, himself, in the black of night....


so, in the end, I was NOT stranded, and, actually, realized that I had NOT run out of power, but it's a lesson in what to really expect when it comes to EVs and 'low power' mode.

The truck did have power, but it's engineering is designed to LIMIT the power when you are at such a low point. It does this by limiting the 'speed' at which you can travel, although it shows on the left diagram/circle as 'Power'... although the two are correlated.
In my situation, when I punched the PEDAL to gain speed and momentum, as you might would do in a gas truck, the LIGHTNING simple said "no"... It is a safety feature.
What it really was doing was limiting my stupidity, in the situation. It thought I was wanting to RACE, with 1% power left. No, it would not do that. It brought the truck to a stop.

Pause. Let the truck see a lack of power need, then, carefully, slowly, proceed.

I probably could have easily and slowly continued up to my son's driveway, in the first place, but, I had asked the truck to do something it was not prepared for.


ALL IS WELL. : ) 49,000 + miles later....

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