HV Battery Died with 7 miles range left showing on Range display

[Marks321]

I merged your new thread with this one since it was the same topic, and already has a lot of feedback on it. Its somewhat interesting to me that the OP of this thread had the exact same amount of miles left as you (7).

In any case, there is a lot of feedback in this thread on the situation. You have one heck of a commute, and have already passed the battery warranty due to miles driven, so hopefully you dont have a battery issue that necessitates replacement.

Thank you

 

[Marks321]

following up, hoping for some more responses, i did read through the entirety of the thread and did find some interesting insights...
I'm willing to stop and charge, its certainly cheaper to get home and charge but now if estimated arrival is less than 12 miles or 4% ive agreed with the wife to stop and top off charge. But it would be great if I could do my 5 day a week 48 weeks a year commute without needing that extra charge .. at least I got that for the first couple years of ownership I guess, though it seems with each year this situation will get worse and a stop to charge will have to be the norm for my 186 mile a day average commute.
I fully charged after the tow truck dropped me off in the driveway, I adjusted the amps to 28 so it would finish charge 30 mins before i have to leave for work.
it charged from 7 to 284 miles, 3% to 100% adding 65.4 kwh to the car while drawing 73kwh from the house, it was chilly 44F so some preconditioning before i left.
then I drove for 93 miles over 96 minutes avg 325wh/mi, arriving with 52%, 47.6% was on consumption screen. averaged 70mph on the highway, slower in Manhattan, but overall average speed for trip under 60mph.
I dont want to charge to 100% more than i need to, i usually reserve it for the worst of the worst cold or snowy days, or before a trip, or if extra errands are planned. while making sure it doesn't sit at 100 for more than 30 minutes.
I used to have a good deal of trust in the system, that there was a slight buffer past zero or that i could at least get to zero.
running out and getting stuck with 7 miles left sure does suck, started service apt request but expecting the same response the author of the thread received

 

[Pianewman]

Marks321: Your numbers don't seem excessive.

So, if my ICE vehicle runs out of fuel with "x" number of miles remaining on the estimate on the dash, I know that I won't ever challenge that number. Ever. If I do, and the ICE vehicle runs out of fuel, it becomes operator error. Why would your MY be any different?

My opinion? You need to adjust your expectations. If the MY doesn't fulfill them, you might need to swap it for a car that does.

 

[E90alex]

Do you have to drive while at work or are you parked for several hours? When you get back home do you start charging immediately?

 

[Marks321]

Do you have to drive while at work or are you parked for several hours? When you get back home do you start charging immediately?

Great question, on the average day I depart 220am get to work by 4AM, work till about 1145am, driving home Noon to 2PM, and plugging in before I grab my bag and head inside, once a month i will wait to plug in to give the battery a chance to sit at a low percent. and on the weekends I only charge to 50% to give the car a rest from the extremes

 

[AlanSubie4Life]

Great question, on the average day I depart 220am get to work by 4AM, work till about 1145am, driving home Noon to 2PM, and plugging in before I grab my bag and head inside, once a month i will wait to plug in to give the battery a chance to sit at a low percent. and on the weekends I only charge to 50% to give the car a rest from the extremes

I'd make sure your car sleeps at work (turn off sentry and make sure the contactors open). Does it? That way on your way home at least it has had a chance to re-estimate the charge level close to 50%.

What you see is pretty bad, and Tesla tries very hard to avoid it. It's likely quite unusual. (They have a 4.5% theoretical buffer for a reason!!!). It's very bad to have to rely on the BMS adjusting for a dead-reckoning error, since 100%-0% discharges without a break are quite common (and in fact getting close to 0% is probably more likely on a large continuous discharge). But anyway they have the buffer (yours seems to have disappeared). This ensures this sort of problem is rare.

If the car doesn't sleep, the evidence suggests that all Tesla can do is dead reckon the charge level. The BMS doesn't have a chance to make adjustments (see all the complaints elsewhere about how the car loses 2-3% in 15 minutes after it sleeps - this is BMS adjusting the remaining range to the correct value, as @AAKEE has described elsewhere).

There may be situations where the BMS can adjust on the fly, but it's safest to just let the car sleep as much as possible, especially in the middle of a discharge, if you think that you'll be getting close to zero.

You can check the various energy screens to see whether you're seeing a negative adjustment - I'd expect you would, if your car was not previously sleeping at work, since you're having this problem.

I fully charged after the tow truck dropped me off in the driveway, I adjusted the amps to 28 so it would finish charge 30 mins before i have to leave for work.

I'd make sure the car sleeps before leaving. Probably doesn't matter much at 100%, but since you're having this problem, it might be worthwhile. It might be a wasted effort though, not sure.

I dont want to charge to 100% more than i need to, i usually reserve it for the worst of the worst cold or snowy days, or before a trip, or if extra errands are planned. while making sure it doesn't sit at 100 for more than 30 minutes.

I wouldn't worry about that at all. An hour or two each day at 100% isn't going to matter much, and your situation ensures that most of the time you're close to 50%, which is pretty much ideal.

Just charge to 100%, and see if you can get the car to sleep. Then leave for work.

 

[E90alex]

As mentioned it’s good to let the car sleep at various states of charge so it can recalibrate the BMS. Your use case is similar to the original poster of this thread where they nearly use the full battery every day, which seems to throw off the BMS after a while.

What do you typically charge to at home and do you have sentry mode or summon standby on at home? Does it finish charging in the middle of the night and sit until you leave or do you have it continuously charging until just before you leave?

For your use case I would make sure to turn off sentry mode and summon standby at work and at home. And assuming you don’t have to deal with TOU electricity rates, I would set it to start charging at least 2-3 hours after you return home and finish charging 2-3 hours before you leave again.

That way the BMS can get daily readings at near full, near half and near empty. It would also be good to charge occasionally to 100% 2-3 hours before you leave so the BMS can balance the cells and also get a reading at 100%.

Otherwise if you have sentry mode on at work, start charging as soon as you get home, and you finish charging right before you leave again…the car never sleeps and BMS never gets a chance to take measurements and recalibrate.

 

[Marks321]

great points, I do usually have sentry on but now that i dont have the energy to spare I'm going to stop using it. that should help it sleep a little more.
as for the charging at home, the car generally charges from 2pm to 10pm 10-90%, then when i wakeup at 2am it gets an extra 5-7% if needed for the day. some days i'll let it charge continuously to 100% and adjust the amps down such that the charge finishes around 2-3am when I'm leaving for work

 

[Marks321]

Got home with 19 miles yesterday decided to let it sit there for two hour before charging. When starting the charge it indicated 10 miles. It added 128 miles to end at 138 miles or 50%
This makes me think the BmS made some adjustments to what it considers 10 or 19 miles while sitting there at low state of charge and resting. Going on vacation now so it gets to rest for a week at 50%

 

[gaspi101]

Ok I have a bone to pick with the Tesla apologists here. If we are driving the car as recommended and charging as recommended, it is absolutely unforgivable to have a system that tells you you have 6% battery left and then suddenly die on the highway. I’d like to think I’m a highly-tech saavy individual, make sure to do a BMS calibration at least one a month, charge every 3-4 days to get readings at different stages between 20% and 85%, monthly charge it to 95% and let it sleep for 30 min before driving, etc. It’s work to think about all of this.

And then to have the friggin car die on the highway TWICE now at 3% and then at 6% is an absurdity. It should be noted that in each of those instances, I was following the Tesla navigation instructions to the letter.

If the system doesn’t work as directed and when following direct instructions, the problem IS TESLA. Not us. If they can’t tell what the battery degradation is and the car is likely to shut down in the middle of the highway when at a low state of charge, they should say that. This brings the effective battery range of the car to maybe 15% less of whatever the actual battery indicator says (which already is supposed to have degradation reflected).

Sorry, folks, I love my cars. But I can’t abide this issue not being an outrage for the community. If this is normal, then Tesla needs to immediately increase their battery buffer by 15% to make sure the Nav computer doesn’t leave you stranded.

 

[gaspi101]

following up, hoping for some more responses, i did read through the entirety of the thread and did find some interesting insights...
I'm willing to stop and charge, its certainly cheaper to get home and charge but now if estimated arrival is less than 12 miles or 4% ive agreed with the wife to stop and top off charge. But it would be great if I could do my 5 day a week 48 weeks a year commute without needing that extra charge .. at least I got that for the first couple years of ownership I guess, though it seems with each year this situation will get worse and a stop to charge will have to be the norm for my 186 mile a day average commute.
I fully charged after the tow truck dropped me off in the driveway, I adjusted the amps to 28 so it would finish charge 30 mins before i have to leave for work.
it charged from 7 to 284 miles, 3% to 100% adding 65.4 kwh to the car while drawing 73kwh from the house, it was chilly 44F so some preconditioning before i left.
then I drove for 93 miles over 96 minutes avg 325wh/mi, arriving with 52%, 47.6% was on consumption screen. averaged 70mph on the highway, slower in Manhattan, but overall average speed for trip under 60mph.
I dont want to charge to 100% more than i need to, i usually reserve it for the worst of the worst cold or snowy days, or before a trip, or if extra errands are planned. while making sure it doesn't sit at 100 for more than 30 minutes.
I used to have a good deal of trust in the system, that there was a slight buffer past zero or that i could at least get to zero.
running out and getting stuck with 7 miles left sure does suck, started service apt request but expecting the same response the author of the thread received

Same, Tesla just sent me links to charging habits articles. What did they say to you?

 

[gaspi101]

As the only person outside of Tesla with any real knowledge of the inner workings of the Tesla BMS: Respectfully, you have no idea what you're talking about and should probably stop. Also, I've made no personal attacks, so probably best to not try to lie about such things.

Tesla's BMS tracks more variables than any other BMS I've examined. It's even able to accurately calculate many things that it has virtually no way to directly measure, either because doing so is actually impossible or because the hardware has no way to do so because it'd be prohibitively expensive or complex.

It is by far the most accurate and well thought out system available to the public by far based on everything I've seen over the years. There's no "black magic" going on here. It's the result of well over a decade of real world research and development put into action in what's by far the best BMS hardware and software on on the market.

I'm quick to jump on Tesla's case when they do something shady, cut corners, or otherwise do something wrong. But I'm also going to give them credit where credit is due, and their BMS is something that's entirely under rated and deserves substantial kudos. So I'll definitely defend them on this particular point, because they've more than earned it.

Their BMS system is fantastic for prolonging battery health. Great. How about addressing the issue for which this thread was started: the car shuts off in the middle of the highway with significant battery range left on the dial and the energy screen. If the BMS simultaneously shows 6% on the dial and also the car shuts off mid-highway for insufficient charge, then it’s a problem. What’s your justification for the car showing both on the screen: 6% battery / 15 miles left on energy screen, and yet the car is shut down for insufficient charge? Isn’t this rather indefensible??? We rely on these systems to do roadtrips. If it shuts off at 3%, and 6% for me, not surprised others have had shutdowns at 8% and 11% with no warning. That’s BANANAS.

Yeah, I get it, the BMS from Tesla is a technical marvel of modern engineering. And so are their auto wipers—at the end of the day I just want it to do what is most important: Not friggin lie to me!

 

[AlanSubie4Life]

Ok I have a bone to pick with the Tesla apologists here. If we are driving the car as recommended and charging as recommended, it is absolutely unforgivable to have a system that tells you you have 6% battery left and then suddenly die on the highway. I’d like to think I’m a highly-tech saavy individual, make sure to do a BMS calibration at least one a month, charge every 3-4 days to get readings at different stages between 20% and 85%, monthly charge it to 95% and let it sleep for 30 min before driving, etc. It’s work to think about all of this.

And then to have the friggin car die on the highway TWICE now at 3% and then at 6% is an absurdity. It should be noted that in each of those instances, I was following the Tesla navigation instructions to the letter.

If the system doesn’t work as directed and when following direct instructions, the problem IS TESLA. Not us. If they can’t tell what the battery degradation is and the car is likely to shut down in the middle of the highway when at a low state of charge, they should say that. This brings the effective battery range of the car to maybe 15% less of whatever the actual battery indicator says (which already is supposed to have degradation reflected).

Sorry, folks, I love my cars. But I can’t abide this issue not being an outrage for the community. If this is normal, then Tesla needs to immediately increase their battery buffer by 15% to make sure the Nav computer doesn’t leave you stranded.

This is really bad. It usually indicates a failing battery of some form.

What vehicle type? Do you have some pictures?

Definitely very abnormal. It sounds like your BMS has no idea what is going on and Tesla will need to fix it. You have to make them go into the logs and figure out what happened at 6%.

Definitely completely unforgivable and not something that should happen. 6% is HUGE amounts of margin. It's not even close to an empty pack (it's about 10% left!). To put it in perspective, that's the amount of energy my Spark EV battery has in it when it is at around 40%, and can travel another 20-25 miles. (Yes, obviously it's a higher SOC & voltage for the Spark cells at that same energy content, which does matter.)

This is a serious issue. Definitely FORCE Tesla to look at it, go through the logs, and if necessary, replace your battery under warranty, if it is still under the mileage limit. This should NEVER happen. There's no excuse whatsoever for a failure like this. It's a warranty issue, for sure.

Unfortunately if you don't have documentation you may need to document another premature shutdown under controlled conditions. If nothing else this needs to be extensively documented within the valid warranty period just in case it fails out of warranty, so it can be covered under warranty outside of warranty.

it is absolutely unforgivable to have a system that tells you you have 6% battery left and then suddenly die on the highway.

Absolutely unforgivable. I note you have a P3D with 265 miles at 100%. This is absolutely massive capacity loss (20%!!!) and represents a pack that is really struggling and way outside the norm of capacity loss (my 2018 P3D is at ~292 miles). You do live in a warm climate and probably have kept the pack above 55% a lot.

This may be a contributing factor and your pack is probably on the verge of failure. It's a major safety issue. It's routine to rely on a pack to operate down to ~0%.

 

[BitJam]

If we are driving the car as recommended and charging as recommended, it is absolutely unforgivable to have a system that tells you you have 6% battery left and then suddenly die on the highway.

Total bummer to have that happen. Saying it is unforgivable seems extreme. It's a car. it is not uncommon for things to go wrong with a car.

The Out of Spec channel has been reviewing EVs for many years. Their standard procedure for road tripping a Tesla is to pull into a supercharger station with as little charge as possible, often 1%. It works for them. They have never been stranded doing this. When they range test Teslas, they will keep driving it after the car reports it has 0% battery left. This also works for them.

Out of Spec has run out of charge when driving an EV a total of three times. All three times it was with a Ford F-150 lightning.

 

[AlanSubie4Life]

Their standard procedure for road tripping a Tesla is to pull into a supercharger station with as little charge as possible, often 1%. It works for them. They have never been stranded doing this. When they range test Teslas, they will keep driving it after the car reports it has 0% battery left. This also works for the

Yes, this is a huge difference vs. the described behavior. Out of Spec routinely uses up some of the buffer. (In general one should not do this, but going to 0% should be fine.)

Saying it is unforgivable seems extreme.

I don't think so. This is a major safety concern. Getting stuck on the highway when driving responsibly with an EV (stopping to charge before it reaches 0%) is dangerous and frightening. Driving to 5% gives TONS of margin to 0%.

It's really not ok, and it's not supposed to happen. This is why Tesla has a buffer. A shutdown at 6% is an indicator that the BMS is not able to keep the pack going at lower SOCs. It's possible it has too high internal resistance, too much imbalance, or some other major critical failure issue.

It would definitely be interesting to see some SMT data on this pack as it approaches the failure point.

I try to drive to 5% when getting to Superchargers. I'd be super upset if I had premature shutdown in the middle of the desert somewhere because it shut down super early like this.

 

[flixden]

Yeah. I would also consider this to be a very serious issue. Hoping Tesla will look into this for @gaspi101 and fix it.

 

[brainhouston]

yeah it would be good to log bms data with SMT near that shutdown point to see whats happening
normally if imbalance or such happens it should throw an error.. so its strange..
i wonder if maybe fast acceleration caused voltage sag n tripped min V for shutdown...(don't know what it is)
does anyone know if car limits power at some low SOC?
i've only ever driven once to 5% but never gave it a punch
Out of spec reviews always say cars power gets limited when they get close to zero but i don't recall exactly when...

 

[AlanSubie4Life]

does anyone know if car limits power at some low SOC?

It limits power below 10% SOC or so, maybe even higher. I don't know whether I've gone below 5% but I've seen limited power due to SOC. So it's supposed to prevent excessive sag (though I wouldn't count on it).

 

[AAKEE]

It limits power below 10% SOC or so, maybe even higher. I don't know whether I've gone below 5% but I've seen limited power due to SOC. So it's supposed to prevent excessive sag (though I wouldn't count on it).

Power is limited higher up.

PMax = ~ SOC x battery temp
So at low SOC and low battery temp we get low pwr, if the battery is warmer at the same SOC we get more power.

 

[AAKEE]

The running out of juice-issue must come from the fact that SOC can not be measured during the drive.

It is calculated from the last known SOC (which could be of if the car was not sleeping or there was a load on the battery).

Last known SOC = recalculated to a nominal remaining energy.

(Nominal remaining- used energy)/ nominal full pack = calculated SOC.
This will be ”preliminary” as ling as the car has not been in resting, with the battery with low/no load for a while.
The largest SOC adjustment sets in during the first 15 minutes of the rest.

Having a BMS that overestimates the capacity will end up with the BMS overestimating the SOC during a drive.

When the car stops at a displayed SOC other than 0% this is because the BMS calculates the SOC wrong, which mostly (to not say always) comes from a overestimated capacity.