What Constitutes Battery Replacement Under Warranty for Older Batteries?

[Recell]

@Recell so this cannot be trusted in SMT?
View attachment 935433

we’ll then, seems we need to enable auto update software

we pull CAC through a separate interface, so this is a welcome improvement to SMT

btw: nice balance! the CAC on that is well within 99 percentile.

 

[Recell]

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.

no, the CAC values are accurate, direct from the BMS - we just hadn’t seen this in the Android version. again, we pull CAC data through a separate interface, so hadn’t seen this in the latest revs of SMT

 

[Paige111]

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

In not looking for a replacement @ this time, just would like T support to acknowledge my battery is degrading too quick & they will address it when it degrades > 30%. If they cant acknowledge my battery issue now, they prob wont acknowledge a battery issue >30%.

 

[ucmndd]

btw: nice balance!

I think you meant “nice CAC!”

I’ll be here all night folks

 

[islandbayy]

@Recell so this cannot be trusted in SMT?
View attachment 935433

Is there a specific way to see the CAC values? I have the most updated version of SMT and cannot find the CAC numbers anywhere???

 

[kirkusss]

It’s under the Battery tab, but being a calculated value it takes few minutes to appear.
Will check on Android in a bit to see if it’s being displayed.

 

[islandbayy]

It’s under the Battery tab, but being a calculated value it takes few minutes to appear.
Will check on Android in a bit to see if it’s being displayed.

Not appearing for me. So your screenshot was from the iOS version?

 

[ajadan]

Seems to me that the iOS version reports CAC and Android does not for some reason. It does take a few minutes for it to show up on iOS. But all the screenshots I've seen with CAC listed are iOS.

 

[EvDart]

Which hardware dongle for sure in 100% working with iOS?

 

[kirkusss]

Obdlink MX+

 

[kirkusss]

Was checking the differences between iOS and Android and for me it looks iOS is more reliable (battery capacity in special). And it took less than 2 minutes to get the CAC values
@Recell if interested

 

[Recell]

awesome

<installs iOS version>

small nit - min/max/avg CAC can be reported to one decimal place.

big nit - full CAC by brick would help a LOT of people understand battery health. better than voltage by brick would. that said, the Min-to-Avg CAC delta is a VERY decent proxy of pack health. if it’s much more than 3 you start getting into a grey area, even more so if the Avg-to-Max CAC delta is around 1… that’s why displaying min/max/average to own decimal place comes in handy.

 

[ajadan]

awesome

<installs iOS version>

small nit - min/max/avg CAC can be reported to one decimal place.

big nit - full CAC by brick would help a LOT of people understand battery health. better than voltage by brick would. that said, the Min-to-Avg CAC delta is a VERY decent proxy of pack health. if it’s much more than 3 you start getting into a grey area, even more so if the Avg-to-Max CAC delta is around 1… that’s why displaying min/max/average to own decimal place comes in really handy.

Totally wish it had brick-level CAC reporting.

Interesting you use min-to-avg delta % instead of min-to-max. Useful to know; I was wondering if there was a slightly more official of the two calculations to use for imbalance %. SMT is clearly reporting max-min as the CAC imbalance total.

Good news, you can see the values to tenth of an Ah on the “dashboards” if you scroll all the way down to the last pane. Here’s mine right near its demise:

 

[ajadan]

Additional note from all this: the brick ID is almost always wrong or even flat out backwards. In the pic above it says my max CAC brick is 45, when brick 45 is/was the problem child all along. First brick to reach max voltage and first to bottom out at low SoC, demonstrating it’s severely reduced capacity. You have to find the bad brick(s) by manually monitoring individual brick voltages across various SoCs in SMT. Shout out @wk057 for turning me on to that fact somewhere in one of these threads.

 

[Recell]

min-to-max is of course useful, but the min-to-avg and avg-to-max gives you a quick sense of what the distribution looks like. if the deltas are the same (and both relatively small), then the distribution is generally evenly spread and the pack is likely doing fine. if it's skewed, especially when the min-to-avg is greater, then you have one (or more) modules that have likely failed (or is failing) while the remainder are working perfectly fine. because we only see failed/failing packs (after all, we live in a world of failure ) we see this min-to-avg skew A LOT.

(and if the spread is equal, but relatively large - say greater than 6 Ah min-to-max with min-to-avg ang avg-to-max the same - you actually have a pack that has multiple bricks, possibly multiple modules, that have failed, or are failing. that's actually our worse case scenario, and may prevent us from being able to re-certify a pack... )

 

[ran349]

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.

Do you have the formula for calculating those CAC values if they are not given in SMT? I have an older car and am watching it closely since my warranty is up soon.

 

[ajadan]

Do you have the formula for calculating those CAC values if they are not given in SMT? I have an older car and am watching it closely since my warranty is up soon.

Can’t be calculated from other values in SMT. Sounds like only the iOS version gives them out. Not sure if other ways to get that data, but it’s a value calculated and reported by the BMS directly it seems.

 

[islandbayy]

SMT has released an update for Android. A pretty big re-design, and now includes the CAC Values.

 

[Big Dunc]

@re/cell Maybe I should have put this in a pm or messaged your website, but have kept it public in case anyone else has meaningful comment.
I have 2014 MS 85 with approx 75k miles on it. Just before I bought it, three years ago, it had a battery under warranty. Only I suspect that it was repaired rather than brand new.
The car runs fine at present (not wishing to tempt fate).
However, I have noticed a massive trend in 2014 MS battery failures recently, and most have already been replaced under warranty.
I have been through your (excellent) website and the only stumbling block is that I am in the UK.
Hopefully I will never need to call on your services, but it is starting to look like when rather than if.
On your website, you make it clear that you do not want to touch cars out of the USA as it is not practical and you do not want to touch just batteries - i.e. you want the whole car.
Assuming that I could get the car or battery shipped to you at my expense, would you be prepared to carry out the work? (I work in the shipping industry and may be could get it there at a good rate - although EV batteries are a hot topic in shipping right now).
Do you have a a ball park price to replace a 2014 MS85 battery? Feel free to PM me if that is better business wise.
At present this is all academic, but should the worst happen, I like to know what I will do about it.

 

[Recell]

to be clear, work outside the US is always a consideration, never off the the table. understandably, the issue is really international shipping logistics, especially when the physical car is involved, as potential importation issues come into play if it’s a physical car.

provided shipping can be arranged, and we’re always happy to expand our logistics capabilities, we are more than happy to take on ANY pack.

In fact, we already do this today as part of our Preferred Installer program.

Recell

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