What Constitutes Battery Replacement Under Warranty for Older Batteries?

[Tam]

My 2015 90D AWD has 112K miles and a calculated battery capacity of about 64.5 KWh and a 100% range of 223 . It seems like it loses about 1 mile a month (not sudden loss) but that is a rough estimate. I asked Telsa about 6 months ago to look into the degradation, but they said nothing is wrong. I understand that one of the reasons Tesla will replace the battery would be due to faster than normal degredation based on the average, but I don't know if anyone would have a better understadning of this. Thanks for your expertise!

Newer batteries have a digital parameter for replacement: 70%.

No such digital number for older ones. They only say something is wrong when your battery can't hold a charge anymore. That means a slippery slope: 65%, 50%, 30% capacities and Tesla could still say there's nothing wrong because it can still keep on charging.

 

[Marcira]

My 2015 90D AWD has 112K miles and a calculated battery capacity of about 64.5 KWh and a 100% range of 223 . It seems like it loses about 1 mile a month (not sudden loss) but that is a rough estimate. I asked Tesla about 6 months ago to look into the degradation, but they said nothing is wrong. I understand that one of the reasons Tesla will replace the battery would be due to faster than normal degradation based on the average, but I don't know if anyone would have a better understanding of this. Thanks for your expertise!

 

[ucmndd]

What @Tam said. There is no warranty against degradation for a 2015 S. Only outright failure.

 

[ucmndd]

As mentioned in the other thread:

There is no warranty against degradation for a 2015 S. Only outright failure. They don’t replace batteries for “faster than normal” degradation.

 

[Paige111]

Newer batteries have a digital parameter for replacement: 70%.

No such digital number for older ones. They only say something is wrong when your battery can't hold a charge anymore. That means a slippery slope: 65%, 50%, 30% capacities and Tesla could still say there's nothing wrong because it can still keep on charging.

The battery warranty states it guarantees 70% retention for 8yrs or 120K mls -Support is always so vague -I know Ill have support issues when my battery degrades >30% , right now my battery has degraded 11% in 18 months -16K ml—Tesla Service refused to check battery @ app., they said people dont have Tesla 3/Y >3yrs, over phone support mismatch my battery details- they actually said 20% degredation in 2yrs is normal -then itll taper out -I know they wont abide by 70% retention warranty.

 

[Tam]

...they actually said 20% degredation in 2yrs is normal -then itll taper out -I know they wont abide by 70% retention warranty.

That's how the legal system works. If you don't think 20% just in 2 years normal, then you need to put that in the language of the contract.

 

[DerbyDave]

A new article on this subject:

Tesla gives update on battery degradation: only 12% after 200,000 miles

Tesla has released a rare update on the battery degradation in its electric cars. The automaker claims its batteries only...

electrek.co

 

[MP3Mike]

I know they wont abide by 70% retention warranty.

How do you know that? I haven't seen anyone report being turned down with 30% degradation. (Of course I haven't seen anyone report getting to 30% degradation either. It seems that the degradation flattens out, or the pack fails before it gets to that point.)

 

[Paige111]

A new article on this subject:

Tesla gives update on battery degradation: only 12% after 200,000 miles

Tesla has released a rare update on the battery degradation in its electric cars. The automaker claims its batteries only...

electrek.co

The battery degradation on a 3LR is suppose to be < 4%/yr, > 8% is too much. I read somewhere they put 2017 74Kwh batteries in 3LR21. That's a substandard battery for 3LR21

 

[ajadan]

Unofficial word from my Tesla service tech was that for older batteries (those without the 70% range guarantee) that a brick imbalance of 20% is one means of being considered defective. I'd been spatting with them for a few months now over rapid degradation (20-25 miles - about 10% - range loss over 6 months). They had told me the car had a Calculated Amp-Hour Capacity (CAC) imbalance that was significant and worsening but didn't meet criteria for replacement. I was at about 16% imbalance when I first had concerns, and it progressed to 17.5% a couple months later. 20% was the threshold apparently. I kept an eye on the CACs using Scan My Tesla and recently reached 20% imbalance based on: (CACmax - CACmin) / CACmax.

Unclear if coincidence or actual hard stop for the BMS, but very shortly (within a week) after I reached the 20% imbalance, the car threw a BMS_u018 error. Scheduled a service visit and sure enough, I'm getting a replacement battery under warranty!

So it's unclear if simply reaching a 20% CAC imbalance and raising your concern to the SC would result in a battery replacement without a BMS error, but perhaps something to monitor for those of us with older MS 85s or 90s. It's at least one argument to present in your toolkit for replacement if still under warranty.

 

[ucmndd]

So it's unclear if simply reaching a 20% CAC imbalance and raising your concern to the SC would result in a battery replacement without a BMS error, but perhaps something to monitor for those of us with older MS 85s or 90s.

Seems more likely to me >20% is the threshold for the BMS alert, and that’s the magic sauce for a replacement.

 

[Paige111]

That's how the legal system works. If you don't think 20% just in 2 years normal, then you need to put that in the language of the contract.

Tesla should, there should be transparency with the battery size in purchased Teslas, I read most external sites re:Tesla prior to purchase, they all said 2-4% battery degradation/yr. Anyone with battery degredation > 11% in 18 months would be concerned & frustrated w/support response- they give contradicting info, mismatch car w/an older car ect, & service refuse to check battery.

 

[ajadan]

Yes, agreed, not many "hard stops" in the BMS for voltage imbalances per @wk057 and @Recell , but perhaps this CAC imbalance is one. At least its a value that (with SMT and a little calculation) can be monitored by the slightly-above-average-Joe-Tesla-driver and help folks anticipate when that error may arrive.

 

[Recell]

yes, a capacity imbalance will trigger a u018, typically between 15-20% delta in SoC - <goes to dig up spec>

module voltage isn’t a perfect measure, but if you’re edging up toward 100mV delta, a u018 will likely trigger (it will soon or already has)

by way of example, we had a Model S in this week that with an intermittent u018 with a 96mV delta. (again, voltage is only a proxy, not an exact measure of SoC)

 

[ajadan]

yes, a capacity imbalance will trigger a u018, typically between 15-20% delta in SoC - <goes to dig up spec>

module voltage isn’t a perfect measure, but if you’re edging up toward 100mV delta, a u018 will likely trigger (it will soon or already has)

by way of example, we had a Model S in this week that with an intermittent u018 with a 96mV delta. (again, voltage is only a proxy, not an exact measure of SoC)

I ran for over 6 months and multiple software updates at greater than 15% CAC delta. 20% triggered it right quick.

When you refer to a 100mV delta, is that at a certain SoC or voltage range? I also spent several months at greater than 100mV imbalance (at rest, climate off and everything) at various states of charge. Near the end I was at 250-350mV delta near the bottom end of SoC.

 

[Recell]

first a nomenclature clarification - SMT doesn’t report CAC (Calculated Average Capacity), only voltage and SoC min, assuming you are referring to those, not the actual CAC in the above?

as for the 100 mV delta. again, voltage is just a rough proxy, because yes, at low SoC the voltage delta grows dramatically. in the example cited above, the 100 mV delta was between 50%-80%, and even then the car was yo-yo’ing between full charging and u018/max range reduced.

the 20% trigger for the u018 error is certain. we’ve seen it kick in slightly lower, so we provided a range above. put it this way, if the imbalance on the pack is north of 15%, the car may well run, only question is for how long…

6 months is likely the outer envelope, and even then it may continue to yo-yo back and forth between fully charging capability and u018/max range reduced as the balance improves/degrades between charge cycles, until the imbalance/u018 alert finally become permanent.

 

[kirkusss]

@Recell so this cannot be trusted in SMT?

 

[EvDart]

@Recell - I am curious what are you thinking about my case => Clarity around CAC imbalances, voltage imbalances, bad bricks, and battery warranty - 2015 90D

 

[ajadan]

first a nomenclature clarification - SMT doesn’t report CAC (Calculated Average Capacity), only voltage and SoC min, assuming you are referring to those, not the actual CAC in the above?

Second @kirkusss, my SMT app calculates/reports what seem to be valid CAC values. So no, not referring solely to voltages and SoC values. See photos posted above by them in this thread and the other CAC thread I started referenced by @EvDart. It would be very odd that if those aren’t real CAC values that right at 20% imbalance per SMT the error on my car appeared.

I realize CAC is a calculated, and therefore at best, well-estimated value, but that’s implied by the term Calculated Amp-hour Capacity, and I assume SMT is doing it’s calculation very similarly if not identically to how Tesla calculates it. Or perhaps it’s a value calculated and then reported by the BMS itself?

Interestingly, an android user noted not having this CAC info, so maybe only iOS SMT reports this data? That would seem odd since it’s primarily an Android app with more limited iOS support.

 

[ajadan]

I’ll follow that up with a thank you, @Recell. We’re all here just trying to understand more and help each other out, and you’ve been very generous with sharing deep knowledge that is limited to only a handful of individuals outside of Tesla, who also rely on that knowledge to drive their business model. So thank you for helping the community in multiple ways through physical vehicle service and knowledge dissemination.