BEWARE! Model S died at 20% charge

[GlmnAlyAirCar]

Not at all true. SOC is fixed to the voltage. Meaning at 3.95 V (cell voltage) my car always displays 75% SOC. Similarly, 4.09 is 90% and 4.20 V is 100%. This is based on years of empirical measurements on my own car using Tesla’s data. I know what I’m talking about.

However, rated range fluctuates and is not tied to SOC by a constant factor as you suggest. Instead it is based on battery capacity as measured by the BMS using output and input energy.

Further reading here:
Calculate usable battery capacity based on rated miles values

Apparently we are using different terminology to express the same concept. I was about to quote the exact thread you did.

My point is that the range is proportional to the energy available in the battery. I was equating this with SOC. Perhaps my terminology was off.

 

[Dave EV]

Running the battery down to 0 is known to risk bricking the battery.

I'm sorry, but no, there is no risk of bricking the battery if you run it down to 0. The only risk of bricking the battery is running it down to 0 and then failing to recharge the battery in a reasonable amount of time.

 

[apacheguy]

So a single dead cell with very low SoC would make the entire pack show this low SoC. A single dead cell with 0% would make the entire pack show 0%, which I don't think happens, so maybe they don't determine SoC as the SoC of the lowest charged single cell.

Tesla uses cell level fuses so if one cell dies (e.g. shorts) then the fuse is broken and it is isolated from the rest of the cells in that brick. The battery simply cannot work with one brick that is at 0% SOC.

My battery is several years old and it is possible that it has suffered a couple premature cell deaths. However, all the bricks (cell groups within a module) are within 4 mV of each other at rest. The SOC is thus readily determined at rest. Under load, the voltage drops and of course increases the uncertainty of the SOC measurement. However, as soon as the car comes to a stop (with low load) the voltages are immediately back to the resting voltage.

 

[ivan801]

I'm sorry, I stayed out of this as long as my OCB would permit. (Yes, I know I should bite my tongue and keep my mouth shut, but, it didn't happen.) I know better than to never say never. I disagree with the use of absolutes unless a person has all of the facts. I don't have all these facts, but from what I can gleam from what's been written, I think: With such a flag waving title, this thread is likely to get a lot of attention - especially from new owners or prospective owners. And as such its going to be misleading.

In Tesla's defense. It appears that the OP is a recent new owner. I don't see any evidence that would suggest the OP is armed with enough first hand experience or knowledge to make statements like "There appears to be an issue with some of the Teslas, although I have taken my Model 3 down to 3% with no problem and I am sure that many S60 owners have taken their cars down to 0%." Driving one or two or even a half dozen loaners does not quality a person to state "There appears to be an issue with some Teslas" - unless some is actually one.

Running the battery down to 0 is known to risk bricking the battery. There's no recharging from a bricked battery by normal means. OP don't run your battery down to 0 or 3% unless you are willing to risk damaging your car. Continuing to do so, you are going to get some more experience with loaners. Also no evidence or facts to support a statement like "I am sure that many S60 owners have taken their cars down to 0%".

Sorry you got stranded. But you invited fast battery depletion with the - doing 75 mph when it was Super cold, because that hints that you had not given the battery time to have warmed up from being cold soaked. Yes, power consumption WOULD high - that was normal the way you describe what you did. I'm not trying to anger you, but it sounds like you are a victim of inexperience with a Tesla or a Tesla in winter.

Maybe there was something wrong with the battery - yep it sounds like unbalanced (been there). Sounds like it may have been headed towards displaying a problem regardless, but also sounds like it would have gotten you home had you been more familiar with driving a Tesla in cold weather and being easier on the loaner.

Best of luck to you.

I appreciate your feedback, and I have a bit of a re-battle: true, I am new to Tesla ownership, but here is my EV history: 2011 LEAF, 2013 LEAF, 2015 LEAF, 2018 LEAF (still have this one). And I have a couple of weeks in i3. And I've been to near 0% many many times in these cars, you have to if you need to drive 80 miles

Driving 75 mph on I-80 is not fast, it is actually slow. Speed limit is 80, and most cars go faster than that. You state that 20F is super cold. It's not. 10F is not super cold. Super cold is -40F. I have driven in -40F (mostly in E-class Mercedes). I expect that most of the mornings in Utah will be in low 20s or colder between now and end of February. Some days will be down to 0F. This is normal winter for those of us who don't live in Hawaii or Phoenix.

I did some research, and there are MANY Model S cars that had the same type of issue, usually failing right around 20% SOC. And SC tech told me "he have seen this before". By the way, they are still diagnosing it, but it was an isolation error of some sort.

I feel I am justified in my BEWARE title. Especially if the cold weather was a contributing factor. I do not know how familiar you are with cold weather risks, but it can kill you. Literally. Sure, you can also have a flat tire and be forced to wait for a tow, but at least with a flat tire your car is not going to shut down.

 

[BerTX]

I appreciate your feedback, and I have a bit of a re-battle: true, I am new to Tesla ownership, but here is my EV history: 2011 LEAF, 2013 LEAF, 2015 LEAF, 2018 LEAF (still have this one). And I have a couple of weeks in i3. And I've been to near 0% many many times in these cars, you have to if you need to drive 80 miles

Driving 75 mph on I-80 is not fast, it is actually slow. Speed limit is 80, and most cars go faster than that. You state that 20F is super cold. It's not. 10F is not super cold. Super cold is -40F. I have driven in -40F (mostly in E-class Mercedes). I expect that most of the mornings in Utah will be in low 20s or colder between now and end of February. Some days will be down to 0F. This is normal winter for those of us who don't live in Hawaii or Phoenix.

I did some research, and there are MANY Model S cars that had the same type of issue, usually failing right around 20% SOC. And SC tech told me "he have seen this before". By the way, they are still diagnosing it, but it was an isolation error of some sort.

I feel I am justified in my BEWARE title. Especially if the cold weather was a contributing factor. I do not know how familiar you are with cold weather risks, but it can kill you. Literally. Sure, you can also have a flat tire and be forced to wait for a tow, but at least with a flat tire your car is not going to shut down.

I definitely think the BEWARE warning is justified. If an ICE might run out of gas at 1/4 tank on the gas gauge, wouldn't it warrant a "BEWARE"? I might anticipate a Tesla's SOC being pretty shaky at 3% or 5% if I never took it that low regularly, but 20% has me definitely BEWAREd.

 

[PhilDavid]

I definitely think the BEWARE warning is justified. If an ICE might run out of gas at 1/4 tank on the gas gauge, wouldn't it warrant a "BEWARE"? I might anticipate a Tesla's SOC being pretty shaky at 3% or 5% if I never took it that low regularly, but 20% has me definitely BEWAREd.

Isn't this the first time someone has been left stranded at 20% though?

 

[BerTX]

Isn't this the first time someone has been left stranded at 20% though?

We have no way of knowing the answer to that -- this is a pretty limited sample size on TMC. I know someone who had the car shut down at a fairly high SOC (less than 10, but more than 3, also in a classic MS60) when he was 400 yards from a Supercharger. Tesla towed the car 50 miles to a Service Center and checked it out, declaring in in fine shape.

 

[Akikiki]

Since the car in question in this thread is a loaner, we can't just ask the owner to attempt to repeat the same situation - run the car down to 20%. The BEWARE does not consider that this is an single episode with a battery pack that may have been marginal and about to go into an unbalanced state - anyway. And we can't expect the SC to tell us anything anyway, because its their car, not an owner's car. We may never know, but I personally don't believe every 60 is at risk of shutting down at 20%.

 

[ivan801]

Since the car in question in this thread is a loaner, we can't just ask the owner to attempt to repeat the same situation - run the car down to 20%. The BEWARE does not consider that this is an single episode with a battery pack that may have been marginal and about to go into an unbalanced state - anyway. And we can't expect the SC to tell us anything anyway, because its their car, not an owner's car. We may never know, but I personally don't believe every 60 is at risk of shutting down at 20%.

How is being a loaner vehicle makes it more prone to being unbalanced? True, I can't run it down to 20% again, but I could not do it even if I owned it, the car is still being repaired (and looks like it will be in a shop for a while). It probably will get a battery replacement.

This was my second time driving this loaner, last time I drove it I charged it to 100% overnight, and it was on the charged to 90% overnight before I picked it up. So I think it had plenty of chances to get the battery balanced. And how did the battery become "marginal" with less than 60k miles on it?

 

[Akikiki]

You mis-read what I wrote more than once. I am not going explain what I explained and belabor this any longer. Thanks for your time.

 

[Chancellor32]

Ivan801 your title is fine, I have a S60 and its good to hear of these instances as lately I have let my car dwindle down to 9-10%. Sorry it happened to you, hope the M3 gets fixed soon. Just ignore some of the grumpy early adopters lol.

 

[ivan801]

Ivan801 your title is fine, I have a S60 and its good to hear of these instances as lately I have let my car dwindle down to 9-10%. Sorry it happened to you, hope the M3 gets fixed soon. Just ignore some of the grumpy early adopters lol.

Thanks for your comment. I am sincerely trying to understand what Akikiki is trying to say. I did find several reports of the similar issues from S60 owners by searching on Internet, and that is why I tried to raise the awareness of it. As you can probably tell, this breakdown left deep scars (frost bites).

My M3 is now back!

 

[croman]

I've driven my S down to 2 miles of rated range (about .8%) once and many many times below 2-3% (10 miles rated). I've driven my 2014 LEAF to 0 (and kept going for 2 miles at 10mph until I reached my destination).

This is not normal and clearly indicates a bad battery module/pack/BMS. Something definitely was wrong and the title is perfectly fine. Thanks for letting us know @ivan801

 

[supratachophobia]

Below 20%, our 90D will just randomly lose 5%. So, 12 to 7, 8 to 3, 15 to 10. It makes those last miles exciting!

 

[abasile]

I'm sorry, I stayed out of this as long as my OCB would permit. (Yes, I know I should bite my tongue and keep my mouth shut, but, it didn't happen.) I know better than to never say never. I disagree with the use of absolutes unless a person has all of the facts. I don't have all these facts, but from what I can gleam from what's been written, I think: With such a flag waving title, this thread is likely to get a lot of attention - especially from new owners or prospective owners. And as such its going to be misleading.

In Tesla's defense. It appears that the OP is a recent new owner. I don't see any evidence that would suggest the OP is armed with enough first hand experience or knowledge to make statements like "There appears to be an issue with some of the Teslas, although I have taken my Model 3 down to 3% with no problem and I am sure that many S60 owners have taken their cars down to 0%." Driving one or two or even a half dozen loaners does not quality a person to state "There appears to be an issue with some Teslas" - unless some is actually one.

Running the battery down to 0 is known to risk bricking the battery. There's no recharging from a bricked battery by normal means. OP don't run your battery down to 0 or 3% unless you are willing to risk damaging your car. Continuing to do so, you are going to get some more experience with loaners. Also no evidence or facts to support a statement like "I am sure that many S60 owners have taken their cars down to 0%".

Sorry you got stranded. But you invited fast battery depletion with the - doing 75 mph when it was Super cold, because that hints that you had not given the battery time to have warmed up from being cold soaked. Yes, power consumption WOULD high - that was normal the way you describe what you did. I'm not trying to anger you, but it sounds like you are a victim of inexperience with a Tesla or a Tesla in winter.

Maybe there was something wrong with the battery - yep it sounds like unbalanced (been there). Sounds like it may have been headed towards displaying a problem regardless, but also sounds like it would have gotten you home had you been more familiar with driving a Tesla in cold weather and being easier on the loaner.

Best of luck to you.

I disagree that there is a significant risk of damaging the battery by running the charge low. The car's BMS (battery management system) is supposed to protect the battery from excessive discharge, and there is a "buffer" below 0% to protect the battery. Further, the car limits available power when the battery is either cold or at low SOC.

The OP did nothing wrong. The car would have been warming the battery pack from the moment the OP started driving. If the car was indicating that it had 20% charge before shutting down, then there was clearly a fault of some sort. The bottom line is that the car failed. Thankfully, this doesn't seem to happen very often.

Also, driving 75 mph doesn't necessarily mean the energy consumption is particularly high. On a flat road, this might translate to about 40 kW of power, which is still well below a discharge rate of 1C. That's still pretty conservative for a "60 kWh" battery.