User avatar
MKH
Gold Member
Posts: 832
Joined: Fri Nov 02, 2018 5:48 am
Location: Dallas

Re: Battery Replacement Under Warranty

Sat Sep 12, 2020 4:12 am

HI my max kappa value is currently is showing 13. my I3 is a 2015 model. Do you think BMW will honor the warranty just based on the kappa value alone. So far on a good day, the max mileage on a full battery is 55 miles.
Short answer - no.

The battery kappa is a 'guess' using an algorithm that calculates the kappa based on conditions at that time. It changes.

Is yours a REx or a BEV? Makes a difference. REx stated mileage is 71, BEV 83. Using 55 as your mileage you are at 76% if REx and 67% if BEV, but the only way BMW will entertain a warranty replacement claim, is if they fully test the battery, which entails draining the HV pack to zero, then measuring the charge it takes to take it up to 100%.

Is your mileage consistently low? Mileage changes according to driving style and temp. On days when the temp is 100+ F (so the AC is working hard full-time), and I drive a little aggressively, my range - 2015 REx - can be as low as 55. Below 80 F, and drive a little more sedately, and my range will be 70+.
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

alohart
Posts: 2397
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Battery Replacement Under Warranty

Sat Sep 12, 2020 12:24 pm

Magiclamp wrote:
Sat Sep 12, 2020 12:36 am
HI my max kappa value is currently is showing 13. my I3 is a 2015 model. Do you think BMW will honor the warranty just based on the kappa value alone. So far on a good day, the max mileage on a full battery is 55 miles.
All accounts that I've read indicate that BMW doesn't consider the Batt. Kapa. max value when deciding whether to replace the battery pack under warranty. A BMW dealer would have to perform its own lengthy battery pack capacity test which involves fully charging and discharging the battery pack while measuring the energy added or removed from the battery pack. The dealer would charge for this diagnosis which could be several hundred dollars. This diagnostic fee would not be charged if the usable capacity were determined to be less than 70% of the new capacity.

What I plan to do is to charge fully, reset the trip meter, drive until the charge level is as low as possible without risking running out of charge, and then reading the consumption rate (mi/kWh) for this trip. Dividing the distance driven by the consumption rate would be the usable capacity in kWh. I don't know how accurate this would be, but if it is less than 13 kWh, I would be willing to pay a dealer for the usable capacity test.

A big problem with all of this is what the battery management system (BMS) is doing. It can apparently dynamically adjust the usable capacity by changing the size of the high and low charge level unusable buffers. The dealer's maintenance software can apparently restore the original sizes of these buffers which results in greater usable capacity, at least for a while before the BMS adjusts it again. Several i3 owners have reported paying for the diagnosis and being denied a battery pack replacement because the usable capacity had been increased enough by the dealer to avoid a warranty claim.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

Magiclamp
Posts: 10
Joined: Fri Jul 06, 2018 11:58 am

Re: Battery Replacement Under Warranty

Mon Sep 14, 2020 10:55 pm

Based on ur formula, i am only getting 12.5 kap. Did it 2x and both time getting the same result.

3pete
Posts: 117
Joined: Tue Mar 19, 2019 9:03 pm

Re: Battery Replacement Under Warranty

Sun Sep 27, 2020 3:38 pm

Magiclamp wrote:
Mon Sep 14, 2020 10:55 pm
Based on ur formula, i am only getting 12.5 kap. Did it 2x and both time getting the same result.
You may want to try a few more times to get an idea how consistent the result is. My experience is that any metric used to calculate battery state of health has some variation in it that makes it hard to point to a definitive number.

The other piece to consider is that unless you ran the battery until the car literally stopped (I'm not advising doing so), there was charge left. You could divide your value by (100 - the % remaining) to factor in any leftover charge. However, my experience also suggests that the i3 does not display discharging as linear so this value may be skewed.

Here are all the ways I have found to measure state of health. I have been tracking all of these for a while on my car and have seen each one bounce +/- multiple kWh between readings in some cases with little rhyme or reason. These numbers are all from the same reading. Even here, the range between them is 1.4kWh:

1) Batt. kapa. max  from the hidden menu
    (Eg. 13.4 kWh)
2) Batt. Ladung kWh from the hidden menu / State of Charge.
    (eg. Batt. Ladung kWh of 1.8 / SOC of 15% is 12.0 kWh total capacity)
3) (Trip Miles / computer's consumption rate (mi/kWh) for the trip) / (100% - State of Charge)
    (eg. (54.7 trip miles / 4.8 mi/kWh) / (100% - 15%) = 13.4 kWh
4) (Trip Miles / computer's consumption rate(mi/kWh) for the trip) + Batt. Ladung Wh
    (eg. (54.7 trip miles / 4.8 mi/kWh) + 1.8 kWh = 13.2 kWh
5) If you have the Electrified app and a OBDII dongle, you can get the SOH reading from there. Mine claims 69%.
6?) Folks have said BMW's test runs the battery flat and measures the amount of energy it takes to recharge the battery to 100%. My Juicebox smart EVSE measures the energy it passes to the car, however without knowing the exact efficiency for any given charge (did the car use the AC/heat for battery conditioning? etc.) I haven't found a way to use this as an accurate estimate.

If all of these consistently point to a number below 70%, I think you have a good case to go to a dealer and ask for a test (and argue that it should be free), however since BMW claims the car will notify you if the battery has lost enough capacity to trigger a warranty claim you might want to be prepared to have to pay for the test no matter what your data says.

Having said all that, I am paying attention to these threads as well for evidence of battery replacement/ what BMW is actually using to determine the threshold.

jadnashuanh
Posts: 5196
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Battery Replacement Under Warranty

Sun Sep 27, 2020 5:21 pm

FWIW, the conversion from ACV to DCV to charge the batteries is not 100% efficient, not counting whatever power might be used for fans associated with heating or cooling in the process. At 240vac, I've seen numbers around 95% efficiency in the conversion process.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

Cuei3
Posts: 1
Joined: Sat Oct 31, 2020 6:24 pm

Re: Battery Replacement Under Warranty

Sat Oct 31, 2020 6:40 pm

Having range issues (73% Kappa/53 mi. range) with my 2015 REX. Took it to the dealership for a Kappa test and they wanted me to pay up for a software update ($500+) before they would run it. Anyone have this same issue? Corporate finally gave them the software to upgrade but this seems ridiculous. Test supposedly came back at 80% and I will see for myself on Monday since those numbers don't jive. Seems BMW makes it real hard to justify meeting their warranty claims. I still have 2 years and some 67K miles for the battery to go below 70% but my first experience with BMW service has not been good.

alohart
Posts: 2397
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Battery Replacement Under Warranty

Sat Oct 31, 2020 9:30 pm

Cuei3 wrote:
Sat Oct 31, 2020 6:40 pm
Having range issues (73% Kappa/53 mi. range) with my 2015 REX. Took it to the dealership for a Kappa test and they wanted me to pay up for a software update ($500+) before they would run it. Anyone have this same issue? Corporate finally gave them the software to upgrade but this seems ridiculous. Test supposedly came back at 80% and I will see for myself on Monday since those numbers don't jive.
I've read that BMW dealers almost always charge for the capacity test which can take a couple of days to perform. If the usable capacity is less than 70% of the nominal usable capacity, the cost of the test is waived and the battery pack is replaced. It seems that this rarely happens with the usable capacity increasing as a result of the test so that the capacity is >70% of the nominal usable capacity.

I've not read of a dealer requiring that the system software (a.k.a., integration level) be updated prior to the capacity test. Maybe the battery management system (BMS) was updated in a particular system software update such that if the system software is an earlier version, the update would be required to change the behavior of the BMS which would increase the usable capacity.

I wish BMW were more transparent about this. Many owners have been unable to learn the measured capacity but are instead told only that their battery pack passes or fails.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

3pete
Posts: 117
Joined: Tue Mar 19, 2019 9:03 pm

Re: Battery Replacement Under Warranty

Mon Nov 02, 2020 4:52 pm

alohart wrote:
Sat Oct 31, 2020 9:30 pm
I wish BMW were more transparent about this.
Agree. On the one hand, a lot of us (myself included) are paying a lot of attention to a battery pack simply because we think it is going to drop below 70% within the warranty threshold. We are (at least I am) basing this on past performance which may not be an indication of future results. Battery degradation in the i3 may race from 100 to low 70s, but then stay there for a loooong time. It seems most complaints are from people with 1+ year on the battery warranty concerned about a precipitous drop towards the threshold, and accounts of situations obviously below the threshold seem to be quite rare. As long as people can still make their expected trips with 70%, hopefully things will be fine.

On the other hand, the secrecy from BMW only creates more consternation to pay close attention to this. I suppose they may be secretive so no one can 'game their system' and find a way to fail their specific test but it seems suspicious when BMW is the one who:
Administers the test
Will tell you the results of the test
Tells you the cost of a failure of the test has a monetary value that could be around $16k (https://www.sae.org/news/2016/08/bmw-i3 ... t-is-16000)
Wants to charge $500 for upgrading software!?!?!?

BMW won't necessarily replace a full battery for dropping below 70% so the average cost shouldn't be that high, especially after adjusting for battery prices in the past 4 years but there's still serious incentive for them to put a thumb on that scale for a particular outcome.

oldGreyCat
Posts: 8
Joined: Fri Nov 27, 2020 6:25 pm

Re: Battery Replacement Under Warranty

Fri Nov 27, 2020 6:40 pm

I am in the process of buying a 2015 BMW i3 from a used car dealer. It only has 18,000 miles, and so I assumed the battery pack would be close to full capacity. $13,000 plus a decent trade in on my 2009 Honda Fit seemed like a good deal. When the dealer had difficulty getting it charged up to deliver to me, I requested it be taken to BMW, who is now replacing one of the cells. With only 18,000 miles on it, the most likely circumstance I can think of is that the car sat for a long time without being charged and damaged the battery, which is somewhat plausible given the vehicle's history. The dealer openly admitted that he did not understand EVs well, and readily agreed to have BMW check it to protect him as well as me. No money has changed hands yet.

I would appreciate some guidance here. What should I expect from the battery after warranty replacement? When BMW replaces cells under warranty, do they restore full original capacity, or just get it barely over 70% and out of warranty range? After replacement, is it still under the original warranty period and mileage, or is it warrantied for a new 8 years/100,000 miles from the date of the replacement? Should I request that they check the 12V battery as well? What information should I request from BMW and the dealer to reassure me that all is OK? At what point should I renegotiate price, which I agreed to assuming that the battery capacity would be close to that of a new pack, and at what point should I walk away and look for another? Is it worth it for me to pay a different BMW shop to do an independent check for me? Are there other questions I should be asking?

Thanks for any help or advice you can provide!


P.S. I cross-posted this as a thread under Buying the BMW i3. These are my first posts here. I apologize if I violated a rule.

alohart
Posts: 2397
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Battery Replacement Under Warranty

Fri Nov 27, 2020 9:15 pm

oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
I am in the process of buying a 2015 BMW i3 from a used car dealer. It only has 18,000 miles, and so I assumed the battery pack would be close to full capacity.
Not a good assumption for a 60 Ah battery pack (2014-2016 i3's). Many 2014-2016 i3 owners are experiencing a significant actual range loss. It is difficult to determine whether this is due to battery cell degradation or a reduction in the usable battery pack capacity by the battery management system. The first can't be fixed except by replacing the battery pack whereas the second might be fixable at no expense.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
When the dealer had difficulty getting it charged up to deliver to me, I requested it be taken to BMW, who is now replacing one of the cells.
Individual battery cells aren't replaceable. However, modules of 12 battery cells are replaceable. I assume that the dealer found a bad module and replaced only the bad module.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
With only 18,000 miles on it, the most likely circumstance I can think of is that the car sat for a long time without being charged and damaged the battery, which is somewhat plausible given the vehicle's history.
If an i3 is parked with its battery pack at a very low charge level, permanent battery cell damage could occur, but that damage would affect all cells, not just the cells in a single module. However, the charge level shouldn't drop more than about 1% per month due to Li-ion's low self-discharge rate.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
What should I expect from the battery after warranty replacement? When BMW replaces cells under warranty, do they restore full original capacity, or just get it barely over 70% and out of warranty range?
The battery pack warranty covers both defects and capacity loss. Seems like a defective module might be replaced under warranty. If so, only that module would be replaced because the warranty claim was based on a defect rather than excessive capacity loss.

If the dealer determines that the usable capacity is <70% of the nominal new usable capacity, the entire battery pack would likely be replaced. Replacing only a few modules would result in a mix of lower and higher capacity cells which wouldn't increase the usable capacity of the entire battery pack. Because the pack contains 96 cells connected in series, the capacity of the pack is equal to the capacity of the lowest capacity cell.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
After replacement, is it still under the original warranty period and mileage, or is it warrantied for a new 8 years/100,000 miles from the date of the replacement?
In general, items replaced under warranty are covered by the original warranty, not by a new warranty starting on the date of the replacement.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
Should I request that they check the 12V battery as well?
Definitely! If the car was parked for a significant period without having its 12 V battery monitored and charged when necessary, the 12 V battery could be weak if it was allowed to discharge to a low charge level due to vampire loads like the keyless entry system, the burglar alarm, the cellular telematics module, etc.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
What information should I request from BMW and the dealer to reassure me that all is OK?
The original general warranty has almost certainly expired, so only the battery pack warranty remains. I can't think of components other than those common to all cars that could be checked by a dealer. With such low mileage, it's unlikely that components other than the batteries could be bad or weak.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
At what point should I renegotiate price, which I agreed to assuming that the battery capacity would be close to that of a new pack, and at what point should I walk away and look for another?
It's unlikely that your used car dealer would pay BMW for a battery pack capacity test, but that would be what I'd want to know. Unfortunately, BMW seems to give battery packs a pass or fail assessment rather than a usable capacity in kWh or percentage of nominal new usable capacity. There is a calculated usable capacity value in the hidden service menu which would be worth checking even though a single reading isn't necessarily very accurate. The new nominal usable capacity is 18.8 kWh.

If I were buying a used i3, I would not buy an i3 earlier than a 2017 model because that's the first model with the 94 Ah battery pack which seems to be degrading much more slowly than some 60 Ah battery packs. However, the price would be higher.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
Is it worth it for me to pay a different BMW shop to do an independent check for me?
In general, BMW dealers aren't very familiar with the i3, so I feel that it would be a waste of money to pay a different dealer or independent shop to check an i3.
oldGreyCat wrote:
Fri Nov 27, 2020 6:40 pm
Are there other questions I should be asking?
I would want to know whether all recalls and service actions had been performed.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

Return to “Technical BMW i3 Discussions”