Model S shut down at 32 miles, leaving me stranded - why?

[eruben]

Hello all, I've watched this forum but this is my first (desperate) post. Yesterday, my 2017 Model S 75 unexpectedly shut down at 32 miles range (13%). There were no warnings, but while accelerating on the highway the car just shut off, throwing alerts and me and forcing me to a stop with no way to accelerate. Climate shut off, etc. and then nothing would move. The posted range quickly fell from 32 to 0. I was one mile away from a supercharger and was ready to charge had I known this was going to happen...but as it was, I was stranded and had to wait hours for a tow truck. It to take me the mile to the supercharger, jump-started the car using the 12v battery, and finally I could plug in to recahrge. I have stayed far away from a <20% charge since!

What happened? A battery cell imbalance, faulty range display? I thought part of my battery had failed - why else would the range lie to me? I rushed into the service center today, and after all-day tests, they told me "The systems health check passed with no issues. We are now supercharging you to 100%, your car will be ready by 5-530pm". I refused to take the car back without an explanation. The service technician was sort of understanding but said physically everything looks good. "Why did it die at 13% then?", I asked. He suggested that at that low, a quick acceleration might have strained the battery too much, it "rebalanced" and then basically tripped a threshold causing things to drop to 0 and shut down. I'm having trouble understanding this explanation. I get it if the range says 5 miles but really it's 0. Or if it said I have 32 miles range and really I only have 25. But why 32 when it's actually 0?

I was also told there was a recent software update and that might have affected things. So I should "let it recalculate by having the range/battery go up above 70 and down below 30". Okay...after doing that, will I then be able to trust the range?

P.S. other relevant information - Software version 2019.20.4.3 57296af. Odometer 17k miles. Also, don't know if it's related, my range at 100% battery has dropped from 255 miles down to 240 overnight, probably because of the same software upgrade. Finally 2 days before all this, I had charged to full and got 255 miles + 25 ghost miles - where I drove 25 miles before the range started decreasing from 255.

P.P.S. one of the worst things (besides being scared to go low in range ever again) is that Tesla says since everything looked fine diagnostically, I must have run out of charge on my own so I have to pay for the $240 tow truck.

(Picture of car shutting down at 32 miles)

 

[Target]

OUCH!

My theory
The heavy acceleration caused the battery to sag and a module went below the minimum threshold voltage causing the BMS to shut you down.

Based on your state of charge and the energy graph I wouldn't have expected that either, but I am always pretty darn careful with the power pedal below 20% because stuff happens.

I have seen mentions in here where customers continue to pursue the issue and eventually prove there is actually something wrong and get their tow reimbursed down the road. Not saying you will have success there, but just FYI.

 

[eruben]

Thank you, "Target". Appreciate your input.

One other thing I forgot to mention (is there a way to edit my original post? I can't find one) is that the service center did find that my 12v battery had a low state of health, and replaced it for me free of charge. Not sure if a failing 12v battery could have caused the shutdown at 13% range?

 

[animorph]

The best the car can do is estimate the energy available in the battery. It is not a precise measurement. If you hadn't been using a significant range of the battery capacity in a long time and filled up to something less than 90% daily then the car was pretty much guessing. Also from information on TMC it is believed that the battery only starts rebalancing when charged somewhere between 90%-100%. Rebalancing makes sure each individual cell has the same charge.

Yes, if you stomp on the accelerator at low states of charge you can trip the battery's safety cutoff and you are dead in the water. At 20% that would be surprising. But combined with the other battery charge anomalies you were seeing, maybe it was not so surprising.

Some good use of the car to 20%, daily 90% charges, and occasional 100% should help avoid most of this. If it is not a battery pack problem.

 

[Target]

Thank you, "Target". Appreciate your input.

One other thing I forgot to mention (is there a way to edit my original post? I can't find one) is that the service center did find that my 12v battery had a low state of health, and replaced it for me free of charge. Not sure if a failing 12v battery could have caused the shutdown at 13% range?

I doubt it because you were looking at the screen, and the screen was working.

It would be possible if it were a flooded type lead acid battery, but AGM's don't usually have plates break loose and start shorting out the battery even under strange conditions. I had this happen on my wife's car a couple years back. Sometimes the car would start and work normally, other times it would be completely dead. The terminals were solid, it was just the battery with an internal short. AGM's aren't really subject to that sort of failure though as they have the glass mats in between the plates.

For fun lets say the 12V did cause it, the contactors would open and the screens would probably reboot. I don't recall seeing a pile of capacitors to keep the MCU alive in any of the tear down videos. However, if you found/find a blown 12V fuse, which would indicate a short in the 12V system, that could potentially spike the 12V system (with a known weak 12V battery) long enough to drop the contactors but leave the MCU running. It would be interesting as the contactors can push energy into the 12V system when they open in a situation like this, and in some very theoretical world, that power may have kept the screen running? Needless to say this is way out beyond edge case stuff and unless you find some indication of a short or some other strange event it is pretty much impossible to have the MCU etc stay on and have the contactors drop out in this way.


Hammering the power pedal at 13% could definitely sag the voltage on the main pack, causing a cell group to fall below shutdown voltage.

20% SOC is where the voltage hits the severe drop where every bit of energy costs you a decent bit of pack voltage, above that the curve is pretty flat until you hit 80% where it rises rapidly. Being well below 20% means your well down that curve.


animorph has a good point, examine your usage and see if the car would have had a decent estimate, or if it would have been pretty far off due to using only the center of the SOC for a long time. You don't have to take it all the way up, but running it through a good chunk of the range in the previous week would have helped it understand the state of the pack. If you had only used a few percent, and then replaced it, for many weeks, then it would be expected to be off.

 

[Tam]

...my 2017 Model S 75 unexpectedly shut down at 32 miles range (13%)...

I've heard cars shutdown at above 0 miles before and I think they've been replaced under warranty.

One recent one is:

Battery runs out with 16% indicated range remaining

...Tesla says since everything looked fine diagnostically, I must have run out of charge on my own so I have to pay for the $240 tow truck...

That's unfair. Car did not shut down at 0 miles. The picture documents that it shut down above 0 miles.

Of course if Tesla does not do a measurement timely, they would get 0 miles. That's why you've got the photo.

I would ask tow truck reimbursement by showing proof with the photo of above 0 miles.

 

[GHammer]

The only time I've heard of this happening the main battery had a bad module.

 

[Gwgan]

Did the power limit appear before the warning messages and the shut down or at the same time? Bjorn has shown that the BMS is unreliable once the power limit first appears and it pays to have a light foot on the go pedal when that happens.
The 12V does not charge when the traction battery is very low but does continue to run the cabin electronics and lights and once the voltage drops too much it does not fully recover.

 

[S4WRXTTCS]

As a hardware engineer I always blame SW people.

Obviously the SW people screwed up.

But, more seriously one should try to charge to 100% around once a month or so. That helps the cells rebalance. I imagine a lot of people don't as it takes forever. I try to, but end ups always having to leave like at 99.99%.

Kinda scary since 13% isn't really that low. I generally try to make sure I don't go much under 13% so I stay above 10%.

I feel like one should even be able to climb a moderate hill at 13%. I don't know if they still show it, but they used to have an indicator that would show the maximum power to expect. So the car actually limits the throttle itself.

 

[Skipdd]

Hello all, I've watched this forum but this is my first (desperate) post. Yesterday, my 2017 Model S 75 unexpectedly shut down at 32 miles range (13%). There were no warnings, but while accelerating on the highway the car just shut off, throwing alerts and me and forcing me to a stop with no way to accelerate. Climate shut off, etc. and then nothing would move. The posted range quickly fell from 32 to 0. I was one mile away from a supercharger and was ready to charge had I known this was going to happen...but as it was, I was stranded and had to wait hours for a tow truck. It to take me the mile to the supercharger, jump-started the car using the 12v battery, and finally I could plug in to recahrge. I have stayed far away from a <20% charge since!

What happened? A battery cell imbalance, faulty range display? I thought part of my battery had failed - why else would the range lie to me? I rushed into the service center today, and after all-day tests, they told me "The systems health check passed with no issues. We are now supercharging you to 100%, your car will be ready by 5-530pm". I refused to take the car back without an explanation. The service technician was sort of understanding but said physically everything looks good. "Why did it die at 13% then?", I asked. He suggested that at that low, a quick acceleration might have strained the battery too much, it "rebalanced" and then basically tripped a threshold causing things to drop to 0 and shut down. I'm having trouble understanding this explanation. I get it if the range says 5 miles but really it's 0. Or if it said I have 32 miles range and really I only have 25. But why 32 when it's actually 0?

I was also told there was a recent software update and that might have affected things. So I should "let it recalculate by having the range/battery go up above 70 and down below 30". Okay...after doing that, will I then be able to trust the range?

P.S. other relevant information - Software version 2019.20.4.3 57296af. Odometer 17k miles. Also, don't know if it's related, my range at 100% battery has dropped from 255 miles down to 240 overnight, probably because of the same software upgrade. Finally 2 days before all this, I had charged to full and got 255 miles + 25 ghost miles - where I drove 25 miles before the range started decreasing from 255.

P.P.S. one of the worst things (besides being scared to go low in range ever again) is that Tesla says since everything looked fine diagnostically, I must have run out of charge on my own so I have to pay for the $240 tow truck.

The fact that your range has also dropped (your P.S. comment) makes me wonder.. look at this thread (warning, it is long). Am not as technical as many posting there. My question would be, IF your car’s battery were affected as those were on this thread, would that explain what happened to you? I will copy one of the key posters on that thread to see what they think. @sorka

Sudden Loss Of Range With 2019.16.x Software

 

[brendon1970]

The obvious answer is to reproduce the problem. This time with a friend in tow! Most likely you have a failing battery or eyes.

Ignore the charge to 100% advice, Tesla batteries balance below that. Ignore the imprecise BMS comments its better than that and faulted.

If the cars cant reliably run to ~0% then driver confidence would be eroded.

 

[Tam]

...If the cars cant reliably run to ~0% then driver confidence would be eroded.

Agreed! Very bad publicity if Tesla considers that it's "normal" for its cars to shut down above 0% or 0 miles.

Elon Musk himself said:






If you see the other post, my Model 3 was fine at 9% or 28.66 miles left which is below @eruben 13% and 32 miles.

 

[Ande]

The BMS cannot exactly know the state of charge of every cell pack in serial, unless it expiry it go near empty and full now and then.
That said, the balancing is not only done above 90% SOC, but BMS every calibration may require seeing 20...90%

That said, the worst mistake here is to think acceleration that bring down the voltage is a good cause for shutdown.
I sometimes hammer it while approaching SC with low SOC, just to arrive with less than 10% to get a better energy estimate. ( Allow BMS to learn a wider range) and while I get kW limit, it's obvious that the car does reduce torque, not just shut down.

Deep cycles are not good for battery, so don't do that regularly.

That said, you would not usually try to drive in ICE car down to the last drop of fuel, or 0km estimate

 

[eruben]

Thanks all, I appreciate your input. I guess it wasn't the 12v battery then. Still can't figure out if it was a hardware (battery cell) or software (unnecessary shutdown) issue. Service center said the battery looked completely fine, but who knows. They kept telling me it was a battery rebalancing issue. But you'd think that under low battery conditions, when trying to accelerate/output a lot power, that the BMS would know to reduce output vs shutting down the car, right?

I usually keep between 30-90%. I put to 100% two days before this all happened because I was taking a road trip. Then I was about 20%-60% for the two days until I hit 13% and shut down.

Did the power limit appear before the warning messages and the shut down or at the same time? Bjorn has shown that the BMS is unreliable once the power limit first appears and it pays to have a light foot on the go pedal when that happens.

It all happened at once - warning messages appeared and sounds went crazy right as the car shut down and told me to pull over. I quickly took a picture, moved to the side of the road, and put in tow mode before it all died.

Overall I'm going to guess that it was a combination of the new charge software changes, with my sudden acceleration at low battery. I just really don't want to try to repeat the experience, and I guess my new lower range limit is 15-20% unless I'm ready to risk it all!

 

[Rocky_H]

Interesting. I've been around both forums for about 5+ years, and I would say basically just like @[email protected] . I have seen this a few times, and it is not OK.

For the people who are trying to excuse this away about mis-balance and how hard acceleration could sag something or how the BMS is only estimating, etc. etc. Those are "kernel of truth" types of things, but are being completely misapplied to these circumstances. The battery was still showing in the yellow zone, for pete's sake!

Shutting down above 0 can be a normal thing only if it is very very close to 0. I've seen several where it would shut down when it is about 3 or 4 rated miles left on the display. Sure, that is in the area where you're talking about variation down to a last 1-2% and you're just into noise variation at those levels, where maybe it's just not that precise, so a little imbalance could hit when it's that low. But at 32 miles or 13%? No--that's something else.

Also, don't know if it's related, my range at 100% battery has dropped from 255 miles down to 240 overnight,

Absolutely that's relevant. This is the key symptom that I've seen a few times on both forums of one of the bricks of cells in the battery pack failing. That amount of about 15-18 miles dropping off the display suddenly is about the amount of energy in one of those bricks, so it is usually a key tip-off that one is going out. And then for it to show up on the other end too, with it dropping the ability to access some of it with 32 rated miles left shows that it does have some kind of problem reading or accessing one or more bricks somehow.

 

[eruben]

Interesting. I've been around both forums for about 5+ years, and I would say basically just like @[email protected] . I have seen this a few times, and it is not OK...This is the key symptom that I've seen a few times on both forums of one of the bricks of cells in the battery pack failing.

Thank you. I'm not sure what to do though. I brought it in to the service center and they said their tests don't show anything wrong with the battery cells. Should I bring it in again? What else would they do? Should I test it out by going down to 10% to see if it shuts down again, and force the issue? Or should I consider it could be a calibration issue and just live with 240 miles range (216 at 90%, and never letting it get below 48 miles/20%, so therefore I only have 168 miles in a day to really use)?

 

[Incredulocious]

Thanks all, I appreciate your input. I guess it wasn't the 12v battery then. Still can't figure out if it was a hardware (battery cell) or software (unnecessary shutdown) issue. Service center said the battery looked completely fine, but who knows.

Your comment about the 12V battery needing replacement caught my eye because that’s a known issue in the RAV4EV forum and can lead to various spurious behaviors including complete shutdown. And mind you, the RAV4EV has many of the same Tesla components (main battery, drivetrain, electronics) as the original Model S. We learned to make sure the 12V battery remained healthy and many of us replaced it with an AGM battery at the first signs of trouble since an AGM battery can better handle the level of discharging that the 12V battery was subjected to in the RAV4EV and at least the early Model S’s. Don’t know if that’s still an issue with later Model S’s.

There are lots of threads on this topic in the RAV4EV forum:
12V battery failing RAV4EV at DuckDuckGo

You might want to do a comparable search on the effects of a 12V battery failing for Model S.

 

[eruben]

Your comment about the 12V battery needing replacement caught my eye because that’s a known issue in the RAV4EV forum and can lead to various spurious behaviors including complete shutdown.

Interesting...this was actually the second time Tesla replaced my 12v battery. The first was November 2017, a month after my purchase.

 

[Gwgan]

...It all happened at once - warning messages appeared and sounds went crazy right as the car shut down and told me to pull over...

Then I would be worried about the pack battery. Can you get TM-Spy and do a little investigating?
Also try to go down low again, but close to charging and on level ground; if nothing else to enhance your own confidence if it was a one-off.

 

[Rocky_H]

Thank you. I'm not sure what to do though. I brought it in to the service center and they said their tests don't show anything wrong with the battery cells. Should I bring it in again?

I would take it to a different service center to have someone else check it. While the battery was still in the yellow range and hadn't even gotten down low enough to go red yet and suddenly shut off, there is something straight-up wrong, and someone from Tesla needs to figure it out.

I did forget to mention what @Incredulocious and I think @Gwgan were saying about the 12V battery. That may still possibly be related to this. I think if the car detects the 12V really going out right now, it can also trigger that disconnecting from the main battery and shutting off the car if it has those several seconds to do so. So this may be a 12V dying problem also/instead. Which if you said you've had your 12V replaced a couple of times, may even trace back to a problem with the DC to DC battery charging system, which keeps that 12V battery maintained.