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HV Battery Died with 7 miles range left showing on Range display
- Thread starter Evolutis
- Start date
I heard that a CAC imbalance can’t be corrected, only a BMS imbalance. I don’t know if what I read was a reliable source however
Added the info about the battery health test failing to tomorrow's service appointment and got this response 
Great video thanks. I got some notices about shutdown before but it was much more sudden than in the video. In the most recent case (dying with 7 miles left) I don't think I got the "Unable to Drive" earlyish warning, I think it went straight to red "Vehicle Shutting Down - Please Pull Over Safely". I think it was like a 10-second warning. Take this all with a grain of salt because I'm speaking from memory and could have times mixed up or things omitted. In the case of dying with 4 miles left I got more time with the warning. Before any warnings, the car's max allowed speed was around 34 mph on the freeway so you could say that was a warning in a sense. This was about 2 mins before shutdown.
Haven't done this yet and wasn't aware of this until now. Will try this out in the next week or so, thank you.
Found this response in another thread from @wk057 who has a business working on / repurposing Tesla car batteries.
Also credit to @Rocky_H for linking to various threads related to this issue which is where I found this post.
Source: Has your car shut down before it hits zero?
Also credit to @Rocky_H for linking to various threads related to this issue which is where I found this post.
AlanSubie4Life
Efficiency Obsessed Member
Yes, I trust his expertise.
However, I would add that a software update can totally bork the function overnight. So it is possible for Tesla to be generally very accurate with estimation except for batteries with problems, yet simultaneously have problems with the entire fleet for a limited period of time.
It is just possible - not saying that is happening or that your car has no problems. It has problems, but they could be software applying to all, or hardware.
Hopefully you can get some sense talked into the Service team. Shutting down on the highway with a lot of range left (7 miles is a lot!) is not cool.
There’s a buffer, which you should never use. It’s there to avoid this problem and to allow you to use the available displayed miles. So it’s broken as far as I am concerned.
I would never try to push this far, but that doesn’t mean it should not be done. I definitely would not expect to get anything under zero but would be greatly annoyed by a shutdown before then. If that is happening, Tesla should make the buffer bigger and the available range smaller. It won’t change the EPA ratings, which use the entire buffer. It wouldn’t even change the miles displayed; they would just be smaller and click off faster.
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(Disclaimer: Didn't read every word in this thread.)
From what I've skimmed, a bit of a wild guess is this may be an issue/bug related to miscalculating during supercharger routing preconditioning and/or low power preconditioning of the pack in general on the Model 3/Y. Both use the motor stator to heat the pack, even when stationary, which is tricky on consumption metrics. It's generally very odd for the car to stop driving > 0 miles showing. At 4 miles we're only talking ~900 Wh, and ~1.5kWh at 7 miles. So whatever it is, it's not very far off and likely just a bug not accounting for this somewhere. I don't expect Tesla to admit to this, if so, but this seems likely given how "consistent" it is in the few instances I've seen of this happening on the 3/Y.
All of that said, you can throw off the range calculation in a lot of ways. While the BMS is extremely good at being conservative with this, each mile on a 3/Y is worth less energy than on an S/X, so it has to be a bit tighter on its calculations to make 0 really 0. So throwing it off doesn't take as much error.
I wish Tesla would just provide cell voltages and cut-off voltages on display so power users can use this to info to hypermile and such... but I don't see it happening.
From what I've skimmed, a bit of a wild guess is this may be an issue/bug related to miscalculating during supercharger routing preconditioning and/or low power preconditioning of the pack in general on the Model 3/Y. Both use the motor stator to heat the pack, even when stationary, which is tricky on consumption metrics. It's generally very odd for the car to stop driving > 0 miles showing. At 4 miles we're only talking ~900 Wh, and ~1.5kWh at 7 miles. So whatever it is, it's not very far off and likely just a bug not accounting for this somewhere. I don't expect Tesla to admit to this, if so, but this seems likely given how "consistent" it is in the few instances I've seen of this happening on the 3/Y.
All of that said, you can throw off the range calculation in a lot of ways. While the BMS is extremely good at being conservative with this, each mile on a 3/Y is worth less energy than on an S/X, so it has to be a bit tighter on its calculations to make 0 really 0. So throwing it off doesn't take as much error.
I wish Tesla would just provide cell voltages and cut-off voltages on display so power users can use this to info to hypermile and such... but I don't see it happening.
AlanSubie4Life
Efficiency Obsessed Member
In the second case it sounded like preconditioning was not involved.
I would be interested in the trip meter details for each trip and the energy screen to see how long a discharge it was. A bigger continuous discharge without an opportunity to re-assess at the OCV seems like it would be harder for Tesla to get right (though I have had some very long segments and haven’t had an issue - though I have never gone to that low a level).
This was the thread I referenced which provides some documentation on the current woes of the BMS ( which may or at not be new - hard to say, since the new energy screen “Park” and “Drive” tabs makes these more visible, and to some extent “issues” could just now be noticed, rather than not existing previously).
It’s quite common for the BMS to just remove 8 rated miles (or some other value depending on the vehicle), after further consideration.
Keep phantom drain under control
Update, the screen does not accumulate all negative losses, aka gains. Remaining miles went up by 10, 151 to 161, “consumed while parked” went from 18.6 to 18.1. Pretty buggy. So this means actually 8 miles over 48 hours, some of which was real useful use (about 3-4 I would say). So 4 over...
teslamotorsclub.com
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RobDeBank
Member
Thank you for the info, and will certainly try your suggestion, thanks a lot..
RobDeBank
Member
Just to add. I charge to 85% then finish the drive to work. Leave it for 4 days, then that gives me approx 76% to leave to drive home, getting home with 10% thanks again...
Results from service appointment. Summary: Tesla took no action during the appointment, told me the battery is fine and tried to explain that basically the range indicator isn't reliable. I went there, talked to someone for 10 mins and then I left with the car. Car was never seen by Tesla.
The employee said there is no service they can perform. They said they already remotely diagnosed the battery and there were no faults. I asked them if they could do a more comprehensive assessment by for example plugging into the OBD and he basically said there is nothing else they can do that would yield additional information.
This begs the question when their remote assessment does show a fault, what do they do to further investigate?
I received a convoluted speech about how the range indicator is an estimate that varies often, etc. He kept referencing the “15V” low voltage system and made it seem like that played a role in the shutdown which did not make sense to me. No mention of the BMS.
There was no acknowledgment from Tesla that the range indicator was incorrect. It was basically, battery is fine, range is an estimate, don’t take your battery below 10%, have a nice day.
Pretty disappointing.
The employee said there is no service they can perform. They said they already remotely diagnosed the battery and there were no faults. I asked them if they could do a more comprehensive assessment by for example plugging into the OBD and he basically said there is nothing else they can do that would yield additional information.
This begs the question when their remote assessment does show a fault, what do they do to further investigate?
I received a convoluted speech about how the range indicator is an estimate that varies often, etc. He kept referencing the “15V” low voltage system and made it seem like that played a role in the shutdown which did not make sense to me. No mention of the BMS.
There was no acknowledgment from Tesla that the range indicator was incorrect. It was basically, battery is fine, range is an estimate, don’t take your battery below 10%, have a nice day.
Pretty disappointing.
E90alex
Active Member
Wow sorry. What a waste of time. If they weren’t even going to do anything they should have just cancelled your appointment.
Videofrank
Member
That response from Tesla is very disappointing.
I am by no means an expert on any of this like wk057, so I would believe what he says.
I had a 2015 P85D until recently and had the car below 10% a number of times. Most times not by choice as there were very few superchargers in the Northeast back then. I remember being really nervous the first couple times but then got used to it. The car never shutdown on me during that time and I was able to either make it home or to a supercharger.
If I had experienced what happened to you, I would be VERY concerned. I'm not familiar with the MY, (I'm supposed to take delivery by 3/31) but that doesn't seem right, just based on others experiences. Until I got some REAL answers I would change my thinking to 10% is 0%, like others have suggested. I would continue to raise concerns with Tesla though.
Just my .02
exxxviii
Member
Yes, in general, think of 10% to 20% as an empty tank and do not go below unless there are no other options. An ICE is very much the same way, just with different thresholds. But it is also super critical to remember that taking a car to 1% is an order of magnitude different from taking it to 10%. Literally. That is within the accuracy range of the SoC measurement.
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