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

[E90alex]

If you follow the Tesla manual strictly you get an unbalanced BMS. First time discussing this issue?

I mean is there really any evidence of this though? The vast majority of Teslas the wild are charging per Tesla recommendations because the general public can’t/won’t be bothered to micromanage the battery like that. Yet we don’t see massive reports of Teslas dying on the side of the road.

 

[ewoodrick]

If you follow the Tesla manual strictly you get an unbalanced BMS. First time discussing this issue?

Why do you say that?

Charge to 80% normally, charge to 100% for long trips.
Sure, they assume that you take long trips. But if you do so around quarterly, then batteries are happy!

 

[gaspi101]

I mean is there really any evidence of this though? The vast majority of Teslas the wild are charging per Tesla recommendations because the general public can’t/won’t be bothered to micromanage the battery like that. Yet we don’t see massive reports of Teslas dying on the side of the road.

Not dying on the side of the road, but getting false “degradation” concerns. If you drive 10% a day and charge 70-80 every night for a month, the BMS will show much less range. And yes, this happens often and you see it asked every day several times on the very forum. So the recommended regimen for having an accurate BMS reading is to have sleep periods at various SOCs, from 20is to above 90, every few weeks.

Your flippant dismissal and attribution of the issue to my “strange” charging habits is a red herring. If I drove it exactly the way Tesla suggests in the manual, it would not fix this range overestimation problem. It would do the opposite and result in a false underestimation of range.

 

[MP3Mike]

If you drive 10% a day and charge 70-80 for a month, the BMs will show much less range.

Which is much safer than what your vehicle is doing with "balanced" BMS.

Though your pack is probably just on its way to failing, unrelated to the balance state of the BMS.

 

[AlanSubie4Life]

If you drive 10% a day and charge 70-80 every night for a month, the BMS will show much less range. And yes, this happens often and you see it asked every day several times on the very forum.

I charge to 55% routinely with no charges to higher levels for weeks at a time. Every time I check the projection it is rock solid within a mile or two of 291 miles.

It is possible this happened in the past or happens on some vehicles. But I don’t think it is the norm.

Anyway this has nothing to do with your pack issues. With the low 80k miles on your car it probably has nothing to do with anything you have done.

I strongly second the @ucmndd suggestion to keep making your pack do this. It’s kind of a pain and expensive to keep getting towed, but cheaper than having to have a pack replaced outside of warranty. You could maybe bring along a large diesel generator, haha. If you do it near your house and you purchase appropriate towing equipment, you could also just pull the car home, just don’t run over the rope (easy to do).

 

[ewoodrick]

I charge to 55% routinely with no charges to higher levels for weeks at a time. Every time I check the projection it is rock solid within a mile or two of 291 miles.

It is possible this happened in the past or happens on some vehicles. But I don’t think it is the norm.

Anyway this has nothing to do with your pack issues. With the low 80k miles on your car it probably has nothing to do with anything you have done.

I strongly second the @ucmndd suggestion to keep making your pack do this. It’s kind of a pain and expensive to keep getting towed, but cheaper than having to have a pack replaced outside of warranty. You could maybe bring along a large diesel generator, haha. If you do it near your house and you purchase appropriate towing equipment, you could also just pull the car home, just don’t run over the rope (easy to do).

And we are all aware of your results.

But that's not what this thread is.

How many times have you taken it below 5%

 

[AlanSubie4Life]

How many times have you taken it below 5%

I think perhaps just once or twice, why?

 

[Pianewman]

If you do it near your house and you purchase appropriate towing equipment, you could also just pull the car home, just don’t run over the rope (easy to do).

I guess I need to adjust my opinion of all of your previous posts...

 

[AlanSubie4Life]

I guess I need to adjust my opinion of all of your previous posts...

Yeah sadly I have run over the dynamic recovery rope before. Fortunately no harm done, except to the rope. In my defense I did not have power steering or power brakes or regen, which makes it hard and confusing to control the car, and it was dark. This was not a Tesla, it was my poor Spark.

I’m not talking about actual towing equipment. Just have to get home with minimal drama which means you can’t run over the rope.

 

[AAKEE]

And we are all aware of your results.

But that's not what this thread is.

How many times have you taken it below 5%

I use 55% on a daily basis since 3years and 3,5 months.
I often drive longer drives and have charged to 100% a lot, and also bern down to single digit a lot.
From what I saw with the M3P it never diverted from the real capacity from being charged to 55% and drained to 25-45% most days, even if the period with only 55% was > 1 month.

I had one real BMS off situation at that was ~ 5-6 months in my new job, with long drives with alternating 2 and 3 weeks between the job periods. Mostly charged to between 100 and 80% before going to work, having the car parked at ~ 5-20% for a week and charging so I arrived home with ~5-10%.
The BMS went off (showing a capacity ~4%* below the true capacity*) during the time the BMS did get the absolute best information about the capacity.

I do not know why it went off (have no clue), but it was at a time where it was presented multiple low SOCs with sleep and full charges.

My MSP have had a fairly stable capacity estimate and I had a period of ~ 3 months when I did no long drives to work at the end of last year. The car was charged to 55% except for some few longer drives during this time, and most days was charged to 55% and not even driven or only acfew short drives in town, so many days between 55-50%.
So from my point of view, only being around a narrow SOC margin doesnt mean the BMS will be off.

*) I made a 100-0% drive about the time when the BMS was most off, and the delivered energy showed that the BMS was wrong and that the time, and that the capacity estimate before was right, as well as the estimate after the off period (these matched the 100-0% test perfectly).

 

[ewoodrick]

I use 55% on a daily basis since 3years and 3,5 months.
I often drive longer drives and have charged to 100% a lot, and also bern down to single digit a lot.
From what I saw with the M3P it never diverted from the real capacity from being charged to 55% and drained to 25-45% most days, even if the period with only 55% was > 1 month.

I had one real BMS off situation at that was ~ 5-6 months in my new job, with long drives with alternating 2 and 3 weeks between the job periods. Mostly charged to between 100 and 80% before going to work, having the car parked at ~ 5-20% for a week and charging so I arrived home with ~5-10%.
The BMS went off (showing a capacity ~4%* below the true capacity*) during the time the BMS did get the absolute best information about the capacity.

I do not know why it went off (have no clue), but it was at a time where it was presented multiple low SOCs with sleep and full charges.

My MSP have had a fairly stable capacity estimate and I had a period of ~ 3 months when I did no long drives to work at the end of last year. The car was charged to 55% except for some few longer drives during this time, and most days was charged to 55% and not even driven or only acfew short drives in town, so many days between 55-50%.
So from my point of view, only being around a narrow SOC margin doesnt mean the BMS will be off.

*) I made a 100-0% drive about the time when the BMS was most off, and the delivered energy showed that the BMS was wrong and that the time, and that the capacity estimate before was right, as well as the estimate after the off period (these matched the 100-0% test perfectly).

So your answer is none. That added nothing to the thread.

 

[ewoodrick]

I think perhaps just once or twice, why?

Because the poster didn't run out at over 5%. Things looked great at that point.

 

[AlanSubie4Life]

Because the poster didn't run out at over 5%. Things looked great at that point.

First, this is false:

on the highway TWICE now at 3% and then at 6% is an absurdity

Second, I was simply saying that I was not aware of BMS drift issues, with varying schemes of charging. This is what was claimed, which I have not seen, in my particular variation, so I do not think it is typical:

If you drive 10% a day and charge 70-80 every night for a month, the BMS will show much less range.

I was not making claims about not having shutdowns at low SOC% because of my charging method.

I’ll say again: I don’t think any of those details are related to this early shutdown issue. It’s a bad pack.

 

[Cheese Guy]

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

From my experience (granted only one car) failure of the BMS to accurately calculate bottom range is giving you an indication of impending battery failure. My own car died at 3% range left. Figure, okay, no problem, I'll never let it get below 3%. A few months later died at 6%. So I increased my buffer. Next up, dies at 9%. Sure enough, the worsening trend was an indication of battery failure. Ended up getting the BMS_u018 error. Battery was replaced.

 

[parsec]

I've owned a few lifepo electric vehicles that travelled on land and water, designed and built a plugin hybrid car, designed/built a solar/wind powered hybrid boat, and have a Volt and a new MYLR. Even with a pretty good BMS, I would not rely on 2% SOC (maybe 6 miles +/- 6 miles range) as being anything other than dead.

With a 7 mile range indication, I'd want to be careful to sneeze in the right direction to maybe get a few more feet of range.

 

[AAKEE]

I've owned a few lifepo electric vehicles that travelled on land and water, designed and built a plugin hybrid car, designed/built a solar/wind powered hybrid boat, and have a Volt and a new MYLR. Even with a pretty good BMS, I would not rely on 2% SOC (maybe 6 miles +/- 6 miles range) as being anything other than dead.

With a 7 mile range indication, I'd want to be careful to sneeze in the right direction to maybe get a few more feet of range.

Tesla use a 4.5% buffer that you could drive on below 0% displayed. It should be (it is) sufficient to counter small errors.
The things described where the car stops well above 0% is not only nlirmal misscalculations.

 

[dafish]

Like alansubbie and aakee, I charge to 55% abc, use higher charges to whatever as needed for the rare trip. I’ve been under 10% frequently goto 5% when needed. As it happens I ran to 0% this week. Car has been to 100% once in 14 months, not over 85% otherwise. I will supercharge when needed, but obviously that’s hard on a pack so avoid it as possible. For the same reason I drift towards lower rate DC fast chargers when I can linger over a meal or a beer. I suppose I’ve dc charged 8-9 times in its life.

Obviously I don’t worry about BMS problems, and like others in this thread, consider the Tesla BMS state of the art. As do many forum members with extraordinary expertise in the field.

Of course I suspect each generation and model of car has seen revisions in BMS sophistication, but thats a guess.

As to the root issue of this experiencing problems, rare though those these folk are, I can appreciate their frustration. My assumption? I lean towards either failing cells or bad sensors within same. None of which is concrete of course.

 

[dafish]

I charge to 55% routinely with no charges to higher levels for weeks at a time. Every time I check the projection it is rock solid within a mile or two of 291 miles.

It is possible this happened in the past or happens on some vehicles. But I don’t think it is the norm.

Anyway this has nothing to do with your pack issues. With the low 80k miles on your car it probably has nothing to do with anything you have done.

I strongly second the @ucmndd suggestion to keep making your pack do this. It’s kind of a pain and expensive to keep getting towed, but cheaper than having to have a pack replaced outside of warranty. You could maybe bring along a large diesel generator, haha. If you do it near your house and you purchase appropriate towing equipment, you could also just pull the car home, just don’t run over the rope (easy to do).

Alan, when towing one (I assume in neutral) will the brakes still regen when applied?

Of course I bought an f-150 powerboost for a reason…

 

[AlanSubie4Life]

Alan, when towing one (I assume in neutral) will the brakes still regen when applied?

Of course I bought an f-150 powerboost for a reason…

What I learned with the Spark is it is better to not have the car shutdown first, since then regen will be unavailable (this would have been nice!). I don’t recommend any of this. I narrowly avoided doing a lot of damage to my car.

 

[parsec]

The things described where the car stops well above 0% is not only nlirmal misscalculations.

In other words, you are saying that there is a battery issue, I think. That seems likely. I have experienced so many strange issues with my new MYLR that I have not yet developed much faith in anything, but I am glad to hear that you have had good luck with low range indications and cushions.

I am between houses, so will supercharge a few times before moving. I'm very favorably impressed with the SC network. Granted, the car noises and steam blowing off while supercharging are a little disconcerting.