I took my 2014 i3 in for a battery capacity check and BMW added capacity to my battery

[3pete]

There are other stories like this but I figured I'd document my experience here.

All my tracking data on my car suggested my HV Traction Battery was below 70% capacity, including: Batt Kapa max hovering at 13.0 kWh and the Electrified app showing 67% SOH. The GOM indicated a range at full charge to be in the 45-55 mile range. Link to tracking data here:https://www.mybmwi3.com/forum/viewtopic.php?f=11&t=17163&p=68608#p68608


I took it to the local dealer and asked for them to check the battery capacity. They said there'd be a $130 diagnostic fee, which I pushed back on because it didn't sound like a capacity check and because @tezarc helpfully shared their story and invoice here:
https://www.mybmwi3.com/forum/viewtopic.php?f=10&t=17400&p=68984#p68984

While discussing with the advisor, it became clear that they were not aware of the 8yr warranty on the HV battery and once they found evidence of it, they found BMW's guidelines on performing a capacity check. They were kind enough that they offered to waive the fee for the test due to the confusion.

Two and a half business days later, I heard that my car passed with a 73% (a solid C-)!

When I picked the car up, I found some changes. They had to upgrade the car's software to perform the test and sure enough, my GOM range, Batt Kappa Max and Electrified app values changed. Also, some of my "coded" values in the car reverted to stock.


Batt. Kapa Max:
Before: 13.0 kWh
After: 15.4 kWh... Based on one data point.

Vehicle Software (i-step):
Before: I001-17-11-543
After: I001-21-03-530

Electrified app results:
Capacity
Before: 40.8Ah
After: 48.2Ah

SOH %:
Before: 67%
After: 80%

SOC HV % Upper Bound:
Before: 65.9%
After: 77.9%

SOC HV % Lower bound stayed at 8%


Overall, I am pleased with the extra capacity. I am especially pleased that they discounted the $400 labor charge to zero. I will keep tracking my capacity data and report back as things progress. I'm not sure whether to hope that it drops from here or stays consistent.

 

[Obioban]

So the software update increases how much you can charge your battery, from 66% to 80%? I don't think I've seen that laid out before.

 

[alohart]

So the software update increases how much you can charge your battery, from 66% to 80%? I don't think I've seen that laid out before.

If so, earlier versions of the BMS might be buggy or too conservative. Another possibility is that the software update re-initialized the BMS data back to its default values such that the range will return to the earlier lower values after some driving. Hopefully, 3pete will keep us updated.

A more cynical view is that BMW knows that updating the software will at least temporarily increase the usable capacity which would help it avoid a warranty claim against the battery pack.

 

[3pete]

So the software update increases how much you can charge your battery, from 66% to 80%? I don't think I've seen that laid out before.

Yes, according to the way I'm reading the Electrified app. (Small numbers on the SOC HV% section)
Before:

After:

I did just get a look at my car in the mi3 app for iOS noticed it has a metric called "Cell Res. Factor" and "Cell Aging Factor" which the Electrified app does not have. It would have been interesting to know whether that also changed with my car's trip to the dealer.

If so, earlier versions of the BMS might be buggy or too conservative.

It seems very likely that this is the case. Tesla has added (and removed!) range to their cars via software updates, and Jaguar added range as well with the iPace. BMW (and Porsche) tend to be conservative in their published performance specs in general so I could definitely see this translating to a conservative take on BMS.

However... If the BMS is restricting capacity below 70% within the warranty period, it should be fixed for free! I was a bit lucky in that regard but I think owners with evidence that their capacity is below 70% should not have to pay for a diagnosis or software upgrade.

 

[3pete]

A more cynical view is that BMW knows that updating the software will at least temporarily increase the usable capacity which would help it avoid a warranty claim against the battery pack.

The tin-foil hat enthusiast in me couldn't help but notice my capacity increased to exactly 80% after the change, which seems just slightly suspicious that it's such a nice, round number! :lol:

I actually do think that part is coincidental, but the part I can't reconcile is the 73% capacity result that the dealer said the test gave. Electrified went from saying 67% to 80% and I can't come up with a formula for capacity from any of the other numbers in the app that gives me 73%. 73 Seems approximately right for the trend line in my #4) Trip kWh / Remaining SOC chart from my tracking data though.

 

[alohart]

Please let us know how your usable capacity changes during the next few months. If it drops back down to near what it was, that would be evidence that BMW has rigged the capacity test to minimize its liability to replace degraded packs.

 

[user 8033]

Probably going to stick my foot in my mouth on this post, but this is my guess about how this battery degradation thing is working.

Say a car manufacturer sells you a EV with an advertised range of 150 miles and a 8-year battery warranty. The automaker knows in advance that there's yearly deterioration of the battery.

Says so here: "As you might expect, the older a vehicle is, the more likely its battery has deteriorated. However, when looking at average decline across all vehicles, the loss is arguably minor, at 2.3% per year. This means that if you purchase an EV today with a 150 mile range, losing about 17 miles of accessible range after five years is unlikely to impact your day-to-day needs."

https://www.geotab.com/blog/ev-battery-health/

So the automaker knows that after five years you can only go 133 miles in the car on a charge. They also know they're on the hook for eight years of warranty and wouldn't want buyers bad-mouthing their brand because of deterioration causing less travel range.

The smart thing to do would be to partition the battery like a SSD hard drive with software where you start with overcapacity and then have enough capacity left to get them safely to eight years despite the annual degradation. Which is going to be affected by a number of factors such as extreme hot or cold climates etc., like the article points out.

That's my thoughts on how this battery life game is being played.

The article is a good read if you've never seen it.

 

[gt1]

Trying my new shiny tinfoil hat...
If the car approaches the end of the battery capacity, they could remove the top and/or bottom safety limits, giving the car a range boost. It will cause the battery to degrade even faster, but why would they care if all they need for it is to last another year until it will be out of the warranty. It can be checked by monitoring the cell voltages at 0% and 100% indicated charge. Are there tools user friendlier than ISTA to do it?

 

[alohart]

Trying my new shiny tinfoil hat...
If the car approaches the end of the battery capacity, they could remove the top and/or bottom safety limits, giving the car a range boost. It will cause the battery to degrade even faster, but why would they care if all they need for it is to last another year until it will be out of the warranty. It can be checked by monitoring the cell voltages at 0% and 100% indicated charge. Are there tools user friendlier than ISTA to do it?

Hope your tinfoil hat looks as good as mine

I and my tinfoil hat don't doubt that BMW is futzing with the BMS to minimize their battery capacity loss liability.

The Android Electrified app and the iOS mi3 app will show similar battery pack data as ISTA.

 

[3pete]

My understanding is that letting a lithium ion battery get to "true zero" means it is likely to never hold a charge again and charging it to a "true 100%" (especially an aged battery) has a substantial risk that it will catch on fire.

Maybe this gives BMW too much credit, but I would assume they don't want either of those things happening even if it's the day after the warranty period ends. Although they aren't liable for the battery at that point, it could tarnish their brand image.

So, with that in mind, and assuming that we already agree the BMS is programmed to "stash" capacity away from the user over time to account for degradation, I'm guessing that when they programmed the BMS they made some assumptions around battery wear and over the past 8ish years they've learned some things. Maybe they programmed the BMS to stash away a buffer of X% of battery capacity for every DC Fast Charge the car does, or Y% for every 1,000 miles driven.

From examining real-world i3 batteries since the introduction BMW could have realized their rating of X% really only needs to X/2% per DCFC. Or maybe Y% for 1,000 miles is close but they think Y% for every 1,200 miles is realistic.

They may have also thought every year of age should take off Z% only to find that it really doesn't factor in enough to matter.

Essentially if this was the case, they could update the BMS parameters and "give back" battery capacity that the BMS stashed away without risking the integrity of the battery.

Again, maybe I'm giving them too much credit, but this seems plausible to me. I will keep tracking my car's info and update you as time goes on.

 

[3pete]

A quick update here (https://www.mybmwi3.com/forum/viewtopic.php?f=11&t=17163&p=69898#p69898) where I am more convinced that BMW is 'sandbagging' a bit in their BMS which impacts estimated range.

One additional thing I'll note is that with the software upgrade, my battery icon in the bottom left corner of the screen (ignore the circle) changed from this:

to this:

Based on my experience, I would encourage anyone with the battery icon in the top screen to ask for a software update. It's tough to say it's worth whatever BMW will charge for it ($500?), but I suspect it would make a difference in range estimates.

 

[Neil]

Do you know what your previous software version was and what your new version is? (Available in the saved .mpd profile file on a USB drive plugged into the center console.) Should be listed in the file like this: <i-step>I001-17-07-500</i-step>

My 2014 kappa is close to 70% and am waiting as long as I can before bringing it in for a capacity check.

 

[alohart]

3pete's i3 must have had a pretty old software version prior to his recent update because the new battery icon appeared when our i3 was updated to I001-18-11-520. The previous version on our i3 was I001-16-07-506, so the battery icon must have changed between July, 2016, and November, 2018.

If the BMS was updated so that more of the battery pack's capacity is usable, I would be interested in knowing what software version included that update. However, another interpretation of the increase in usable capacity in 3pete's battery pack might be that the capacity test itself, deep discharges and high charges, calibrates the BMS resulting in more usable capacity. I don't recall reading about any capacity test that didn't result in a usable capacity increase.

 

[3pete]

Do you know what your previous software version was and what your new version is? (Available in the saved .mpd profile file on a USB drive plugged into the center console.) Should be listed in the file like this: <i-step>I001-17-07-500</i-step>

My 2014 kappa is close to 70% and am waiting as long as I can before bringing it in for a capacity check.

Yes, I went from: I001-17-11-543 to: I001-21-03-530.

As far as waiting... I'm not sure it's worth it. On the one hand, if your current capacity is adequate for what you need, then great! On the other hand, if you're starting to sweat the range on your trips, it's probably worth getting it checked now. Take your manual, and point to the page that capacity is warranted and must be serviced by an authorized dealer ask them to do the check for free. Worst they can do is say "no".

 

[3pete]

3pete's i3 must have had a pretty old software version prior to his recent update because the new battery icon appeared when our i3 was updated to I001-18-11-520. The previous version on our i3 was I001-16-07-506, so the battery icon must have changed between July, 2016, and November, 2018.

If the BMS was updated so that more of the battery pack's capacity is usable, I would be interested in knowing what software version included that update. However, another interpretation of the increase in usable capacity in 3pete's battery pack might be that the capacity test itself, deep discharges and high charges, calibrates the BMS resulting in more usable capacity. I don't recall reading about any capacity test that didn't result in a usable capacity increase.

It's true that I am associating the additional capacity with the software upgrade, but that may not be true. It could be the actual method of the battery test. I wonder if anyone has had a capacity check done without a corresponding software upgrade?

Software update seems more likely to me just because other manufacturers have done capacity tweaks that way before.

 

[Neil]

I hardly drive my i3 anymore since I stopped commuting 75 miles a day before the pandemic even started. The reduced capacity/range is still adequate enough and it charges really fast now! :lol:. Otherwise, like 3pete said, if I were sweating the range I'd be more aggressive about getting something done about it. However, as I have been assuming that if the capacity is tested to be below the warranty limit I'd actually be able to have battery modules replaced (a hardware fix), this does not appear to be the case for most warranty claims I've heard about. So I'm not sure it is as important to wait, since the increased capacity appears to be due to a software upgrade, the test process, a BMW technician's incantation, or some combination of these and possibly something else and I'd probably have to pay for it anyway. I think those clever BMW engineers planned for this from the beginning to mitigate warranty claims on reduced capacity (a known phenomenon) and only would have to deal with hard battery failures which were shown to be much less likely.

 

[JohnKelly]

The battery capacity icon is selected by going through the menu when you push the button on the end of the turn signal stalk.

 

[Arm]

I hardly drive my i3 anymore since I stopped commuting 75 miles a day before the pandemic even started. The reduced capacity/range is still adequate enough and it charges really fast now! :lol:. Otherwise, like 3pete said, if I were sweating the range I'd be more aggressive about getting something done about it. However, as I have been assuming that if the capacity is tested to be below the warranty limit I'd actually be able to have battery modules replaced (a hardware fix), this does not appear to be the case for most warranty claims I've heard about. So I'm not sure it is as important to wait, since the increased capacity appears to be due to a software upgrade, the test process, a BMW technician's incantation, or some combination of these and possibly something else and I'd probably have to pay for it anyway. I think those clever BMW engineers planned for this from the beginning to mitigate warranty claims on reduced capacity (a known phenomenon) and only would have to deal with hard battery failures which were shown to be much less likely.

You are a shining example of using what you NEED and not what you THINK YOU NEED like so many others.

Well done sir!

 

[Arm]

3pete's i3 must have had a pretty old software version prior to his recent update because the new battery icon appeared when our i3 was updated to I001-18-11-520. The previous version on our i3 was I001-16-07-506, so the battery icon must have changed between July, 2016, and November, 2018.

If the BMS was updated so that more of the battery pack's capacity is usable, I would be interested in knowing what software version included that update. However, another interpretation of the increase in usable capacity in 3pete's battery pack might be that the capacity test itself, deep discharges and high charges, calibrates the BMS resulting in more usable capacity. I don't recall reading about any capacity test that didn't result in a usable capacity increase.

It's true that I am associating the additional capacity with the software upgrade, but that may not be true. It could be the actual method of the battery test. I wonder if anyone has had a capacity check done without a corresponding software upgrade?

Software update seems more likely to me just because other manufacturers have done capacity tweaks that way before.

There's a simple way to find out. Drive the car a few times and see what range you get now after a certain number of miles. The most accurate way I've been able to calculate my range on my car (what it's going to actually give me in current conditions) is miles/% battery used.

For example, I'm averaging around 1.35 miles / % Battery Level. At full charge, I'm hovering around 124-145 miles per charge. I've seen as high as 164 miles at 100%. Overall since the last 1100 miles I've driven since I got my car at the beginning of September, I've averaged 5.1 miles/kWh. My Kappa is 29.2 kWh. So according to that calculation I should get 149 miles at 100% charge. But the miles/% charge is more accurate.

 

[3pete]

There's a simple way to find out. Drive the car a few times and see what range you get now after a certain number of miles. The most accurate way I've been able to calculate my range on my car (what it's going to actually give me in current conditions) is miles/% battery used.

For example, I'm averaging around 1.35 miles / % Battery Level. At full charge, I'm hovering around 124-145 miles per charge. I've seen as high as 164 miles at 100%. Overall since the last 1100 miles I've driven since I got my car at the beginning of September, I've averaged 5.1 miles/kWh. My Kappa is 29.2 kWh. So according to that calculation I should get 149 miles at 100% charge. But the miles/% charge is more accurate.

I tend to avoid looking at Range related metrics for my tracking because it varies too much based on the weather outside because I'm using the heat or AC. But in case you see something useful, here's a chart of that data on my car, duplicated: once colored by before/after capacity check and one colored by temperature. It seems like the orange may be higher than usual but definitely not as pronounced as the capacity charts.

*I threw out measurements above 95% and below 5% battery because those were obvious outliers