E90alex
Active Member
It probably will if he keeps driving it that way. Mine has only seen below 20% once. Much less single digits or anywhere close to 0. It seems like he runs it near dead on the regular.Will the car get worse?
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It probably will if he keeps driving it that way. Mine has only seen below 20% once. Much less single digits or anywhere close to 0. It seems like he runs it near dead on the regular.Will the car get worse?
Thanks, was planning on doing this. Just waiting to get the battery down to 20% or so from driving so the test won't take as long.You can do an actual degradation test from within service mode. You'll need to start with an SOC of sub 50, which really doesn't mean 50% shown within any of the screens as the car has a buffer that isn't avail to any of the calculators.
Start this process with the battery somewhere under 42%, it takes quite a long time(unto 24hrs), and requires you to be plugged into a lvl2 charger the entire time. It will discharge the car to 0 and back up to 100%.
Use this information as you wish.
To answer your question no it’s definitely not normal. There should be a buffer even beyond 0%/0mi so owners won’t get caught out with a dead HV battery like you did. That’s not a great customer experience and as you sad would make people not trust the car.I was already aware that bringing the battery to a very low SOC is not good for the battery health. That's not the issue or my question. My question is if others have had the same experience of the car dying when it shows 4+ or 7+ miles of range left. I want to get a sense for if there is a problem with my battery/car or if this is normal. There have also been some people trying to offer troubleshooting steps or ask questions about my usage which is helpful.
For additional context I'm on track to do close to 43,000 miles this year so I'm put in situations where it's easier to run the battery down vs most people doing say 14K miles. All of the "I don't bring my car below 10%", that's great but not helpful and doesn't add much value to the thread.
I used to think this but then I was corrected. The HV battery is happiest at low states of charge. The problem with going down to zero is it can harm your low voltage battery, but that may be less of an issue if it is Li-ion.Running your battery down to less than 10% multiple times isn't great on the battery.
Nope. Thats a forum truth. People have been misinterpreted the information Tesla gives.
No, its not like that.
There is a ton of research on this and the research results is very consistent on this.
In a few cases the conclusions is ”wrong” because of that the test setup was not good, or the conclusions was faulty because the research test setup did ”hide facts”
More or less any lithium battery is more happy at low SOC.
As Tesla has a 4.5% buffer in the bottom 0% on the screen is about 4.5% and very safe.
Lithium batteries degrade from calendar aging (time) and cyclic aging (charge/drive cycles).
For most Tesla users, the main degradation factor is calendar aging for the first five years or so. Calendar aging lessens with time.
Calendar aging increases with SOC and temperature.
Calendar aging is the degradation that most people confuse with battery lottery.
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0% in research and these tests is the minimum discharge voltage the battery cell manufacturer sets. Thats 2.5 Volts for NCA like Panasonic 2170. (100% SOC is the maximum voltage in that spec.)
Cyclic aging is the other part and the research show us that small cycles is better. Also the lower down in cycle the SOC range, the better.
If you use full cycles, 100% to 0%, the battery would hold for 500-1000 cycles before it have lost 20% (this is constant cycling, without calendar aging).
This would be some 300.000km or 200.000 miles ( -ish).
The average driver will drive about (Roughly) 1/20 of this range each year.
This means cyclic aging will cost us about 1% per year, or less.
Calendar aging with 70-80% average charge would eat some 4-8% the first year depending on the average ambient temperature.
Instead of pointing to one specific research report, I recommend googling for lithium battery + calendar aging and or cyclic aging (or both). Try to stay away from battery universe for this as they actually have some myths in the material (otherwise, they are good). Use real research reports.
To answer your question no it’s definitely not normal. There should be a buffer even beyond 0%/0mi so owners won’t get caught out with a dead HV battery like you did. That’s not a great customer experience and as you sad would make people not trust the car.
Most likely your BMS calibration is out of whack and/or battery cells are not balanced. That’s just further exacerbated by your driving and charging habits. People say the BMS doesn’t take calibration readings unless it’s asleep for a few hours. Since you drive so much the car is hardly ever asleep and the BMS doesn’t get a chance to take any readings at various SOC.
You can try the battery degradation test in the service menu mentioned above and the tips for cell balancing and BMS calibration listed on several websites. Might even need to do it a few times. It will require a lot of downtime of the car to go through those procedures though so unless you have another car to use you might not be able to do it.
Have you contacted service to see what they have to say?
Tesla Vehicle Support here. We see your concerns with the car having a complete discharge still showing miles. Please be advised the range of miles on your car is an estimate amount of how much is left. That estimate amount will factor on how the car is being driven, conditions of elements as well. Please keep your state of charge between 20-80% at all times. Allowing the car to run too low on charge and complete discharge will cause severe battery health and ill perform for you. Please advise that you have received this information. Thank you have a great day.
The battery is in good health still at this point on the car.
Interesting, thanks for pointing this out. I'm going to reserve judgment as this seems to be heavily debated.I used to think this but then I was corrected. The HV battery is happiest at low states of charge. The problem with going down to zero is it can harm your low voltage battery, but that may be less of an issue if it is Li-ion.
There are many posts about this here. For example:
TL;DR: "More or less any lithium battery is more happy at low SOC."
Battery issues like this aren't generally seen in the short-term. They are basically life shortening events. i.e. Many people smoke and don't see harmful benefits for all their life, until they don't exist anymore.I was already aware that bringing the battery to a very low SOC is not good for the battery health. That's not the issue or my question. My question is if others have had the same experience of the car dying when it shows 4+ or 7+ miles of range left. I want to get a sense for if there is a problem with my battery/car or if this is normal. There have also been some people trying to offer troubleshooting steps or ask questions about my usage which is helpful.
For additional context I'm on track to do close to 43,000 miles this year so I'm put in situations where it's easier to run the battery down vs most people doing say 14K miles. All of the "I don't bring my car below 10%", that's great but not helpful and doesn't add much value to the thread.
And 10 years down the road, does it even matter for the first owner?Battery issues like this aren't generally seen in the short-term. They are basically life shortening events. i.e. Many people smoke and don't see harmful benefits for all their life, until they don't exist anymore.
At the investor call today, Tesla said that they use AI to automatically triage, respond to, and order parts for ~33% of service requests. So, it is possible that a person wasn't even involved in that response.Note that I realize thats not exactly what you are asking. Even though thats the case, I am betting thats what whomever sent that response to you read it as, and simply copy / pasted one of their few stock "range" response boilerplates.
I worked on grid storage battery designs for several years. I was not involved, but watched from the next cubicle, for 18 ish months while the BMS engineers debated and tested hundreds of iterations of algorithms to determine SOC of the systems.
It was a total mess. So many variables like temperature, cell imbalance, discharge rate, make it amazingly difficult to pin down. As they stack up racks of modules, it gets even harder to know what the hell is going on. They often couldn't agree on what they were even measuring, how to average the readings, how often to sample them, how to predict and filter smaller swings in voltage, just crazy complicated.
Customer contracts depended on it, warranties accounted for it, it was nuts.
They drank a lot after work.
1. I'm currently running BMS calibration, currently at 52%, haven't charged in a few days.I think OP is still waiting to perform a BMS calibration at various states of charge before bringing the car in again. Tesla won't even schedule an appt because it is running within their tolerances.
I think this is easily correctable once the battery can get an idea of its capacity at 10%, 20%, 50% etc. overnight a few times.