Software update needed for HV battery capacity check

[djbrh]

I have just had the same issue. Battery capacity down to about 65% of original (2014 22kwh battery version) as calculated for each trip and also on the Kappa Max feature on the computer.
BMW were very reluctant to deal with this, but eventually did. They took the car for 6 days and after 2 days asked for me to pay for the software update. I refused as it is a warranty claim and I could substantiate the failing battery. After the upgrade and then testing they said the battery was at 75% of its original capacity. I was VERY sceptical BUT after getting the car it is now running at about 75% capacity as tested. The conclusion has to be that the software update is fixing a BMS issue, or they are manipulating the battery electrically during the testing process to get its capacity up. Either way capacity is not great, but is better by about 15% (of 65%) so they save a warranty claim.
What disappoints me most was the attitude towards me making the claim. I gave them a poor review for the service (survey sent to me after service) and I then got a phone call back from them telling me basically I had no right to give them a poor review. And there I was thinking the survey was to improve their customer service. How silly of me.

These cars, from the factory, only utilized 80% of the *actual* battery capacity. This was by design because they wanted to maximize battery life. Had they let it use 100% we would have all gotten way more range, but the batteries wouldn’t have lasted nearly as many years. But many aren’t making it quite out of the warranty period. BMW changed a few, but quickly realized how much that was going to cost, so they came up with another solution…the software update. All it does is instead of stopping at 80%, it probably goes to like 90% now. That will ultimately reduce your long term life even further, but will probably get them past the warranty window so they don’t care.

I’m not sure there’s anything we as consumers can do about it, since they sold the car based more on the mileage range, and if they can get you within a reasonable percentage of that for the 8 years of warranty that’s all they care about.


—Donnie

[samorth]

It is still fudging the figures. 70% of 18.8 kwh is 13.16, so as soon as the capacity drops below that, the warranty is triggered. If they then open up the "hidden capacity", the denominator is now 22.2 kwh and 70% of that is 15.54, so if all you are doing is redefining the Kappa max (to use their terms), then if the capacity falls below 15.54, that is less than 70% of original, and warranty should be triggered.

This is not hugely dissimilar to the conduct of VW with their defeater chip in their diesel vehicles, and that did not end well for them. BMW need to be held to account. You know they are hiding something because of the cloak and dagger stuff regarding exactly what they do when the car is being tested. 6 days to test a battery raises more questions than it answers.

[alohart]

What really matters is irreversible battery cell degradation. With a BMS controlling battery pack charging and discharging, it's nearly impossible for mere mortals to measure actual irreversible cell degradation. I suppose we could map battery pack or cell voltages to actual charge levels to determine actual usable pack capacity and not depend on the amount of usable energy available. E.g., if we know that a cell voltage of 4.?? V is a 100% actual charge level and define some voltage as an actual 0% charge level (that might be more subjective than the maximum voltage), we could use cell voltage to determine the actual usable capacity independent of what the BMS is doing. The iOS mi3 app, the Android electrified app, and ISTA+ all display maximum and minimum cell voltages, so maybe we could use this information to get a better idea of cell health independent of the BMS. Am I delusional?

[Arm]

Is the 70% threshold for warranty measured from full capacity or usable capacity?

[alohart]

Is the 70% threshold for warranty measured from full capacity or usable capacity?

Nominal usable when new

[samorth]

Its irrelevant. All that matters is, if you start quoting capacity according to the 18.8 kwh (available) you must finish measuring the same. You cannot start measuring the available and then finish measuring relative to the 22.2 kwh total capacity. My battery capacity is down to 65% original, but with the software update opening the extra 2.4kwh for the measurements, it looks like 75% original. And, opening that extra up will result in rapid deterioration of the battery from here on in. But BMW know that will happen out of the battery warranty period, cleverly sidestepping their warranty "obligations" it would seem.
This is dishonesty similar to how VW made ways to evade the emissions standards in their diesel vehicles, and paid a high price for doing so.

[Arm]

Its irrelevant. All that matters is, if you start quoting capacity according to the 18.8 kwh (available) you must finish measuring the same. You cannot start measuring the available and then finish measuring relative to the 22.2 kwh total capacity. My battery capacity is down to 65% original, but with the software update opening the extra 2.4kwh for the measurements, it looks like 75% original. And, opening that extra up will result in rapid deterioration of the battery from here on in. But BMW know that will happen out of the battery warranty period, cleverly sidestepping their warranty "obligations" it would seem.
This is dishonesty similar to how VW made ways to evade the emissions standards in their diesel vehicles, and paid a high price for doing so.

I don't know if I agree with that. What proof is there that rapid battery degradation will occur because they allow more useable battery?

I have a 94aH (33.2kWh) battery. 27.2kWh supposed to be the usable. My Kappa is averaging 29 kWh via only 2 data points...not enough I know but that's all I have at the moment to go by.

So Using Nominal:

70% of 33.2 = 23.3 kWh

Using Usable:

70% of 27.2 kWh = 19.04 kWh

I am assuming that while my car was at the dealership for a week having all warranty work done on it after my purchase that they updated both the iDrive and the car's own software. I have the new battery "symbol" so I'm guessing the battery update was done as well. No way to know on my end.

[djbrh]

Its irrelevant. All that matters is, if you start quoting capacity according to the 18.8 kwh (available) you must finish measuring the same. You cannot start measuring the available and then finish measuring relative to the 22.2 kwh total capacity. My battery capacity is down to 65% original, but with the software update opening the extra 2.4kwh for the measurements, it looks like 75% original. And, opening that extra up will result in rapid deterioration of the battery from here on in. But BMW know that will happen out of the battery warranty period, cleverly sidestepping their warranty "obligations" it would seem.
This is dishonesty similar to how VW made ways to evade the emissions standards in their diesel vehicles, and paid a high price for doing so.

I hear you and I agree that it’s quite the shenanigan to pull, but I’m not sure it’s as clear cut to *prove* in a court of law as you make it seem.


—Donnie

[djbrh]

I don't know if I agree with that. What proof is there that rapid battery degradation will occur because they allow more useable battery?

Because that’s how this particular battery technology works. It’s why Tesla recommends NOT charging past 80% unless you NEED to. It’s why you’re not supposed to charge a Tesla from 80->100% in that case until *right* before you leave if you’re gonna do it. You can ignore both of these recommendations if you want, but they tell you up front if you do that it will shorten your battery’s life.

That’s why BMW only allows 80% to be used in the first place. I’m not sure how you can argue this, tbh.

And I’m not saying a Tesla battery, charged daily to 100%, is going to “degrade rapidly.” I’m saying it’s going to degrade a lot more rapidly than one that ISN’T charged that way, but what “rapidly” is in this case isn’t well defined. What is quite likely, however, is that a 7yo or so battery that’s already degrading and then has more of that ceiling opened up *is* likely to decline pretty rapidly.


—Donnie

[Arm]

I don't know if I agree with that. What proof is there that rapid battery degradation will occur because they allow more useable battery?

Because that’s how this particular battery technology works. It’s why Tesla recommends NOT charging past 80% unless you NEED to. It’s why you’re not supposed to charge a Tesla from 80->100% in that case until *right* before you leave if you’re gonna do it. You can ignore both of these recommendations if you want, but they tell you up front if you do that it will shorten your battery’s life.

That’s why BMW only allows 80% to be used in the first place. I’m not sure how you can argue this, tbh.

And I’m not saying a Tesla battery, charged daily to 100%, is going to “degrade rapidly.” I’m saying it’s going to degrade a lot more rapidly than one that ISN’T charged that way, but what “rapidly” is in this case isn’t well defined. What is quite likely, however, is that a 7yo or so battery that’s already degrading and then has more of that ceiling opened up *is* likely to decline pretty rapidly.


—Donnie

These are assumptions based on fast charging. If you're home charging most of the time, it's not an issue.

It's better to have the car plugged in and be conditioned than not. My garage hits 100 F inside in the summer. If I don't have my car plugged in, it's worse for the battery to sit in that heat all day.