2014 i3 REX with 11.7 Batt Kappa Max

[Bertone]

Do you know the max batt kappa figure of an 94Ah to be used as a reference (I.e 100%) when claiming for the 8 year warranty ?

 

[EvanstonI3]

Do you know the max batt kappa figure of an 94Ah to be used as a reference (I.e 100%) when claiming for the 8 year warranty ?

When "new" the number would have read 29.9 or 30.0 but for "warranty" purposes BMW uses 27.2kWh at least in the USA.

 

[alohart]

Do you know the max batt kappa figure of an 94Ah to be used as a reference (I.e 100%) when claiming for the 8 year warranty ?

Have you read of any 94 Ah or 120 Ah battery pack losing more than 30% of its original usable capacity? I haven't. These battery packs seem much more resistant to capacity loss than many 60 Ah battery packs. Unlike when we owned a 2014 i3, I don't worry at all about capacity loss in our 2019 i3.

 

[petern12]

There's no way that replacing a 60 Ah battery pack would cost BMW $30k+. That ridiculous price is due to BMW's huge parts markup and high hourly labor charge.

Have you read of any 94 Ah or 120 Ah battery pack losing more than 30% of its original usable capacity? I haven't. These battery packs seem much more resistant to capacity loss than many 60 Ah battery packs. Unlike when we owned a 2014 i3, I don't worry at all about capacity loss in our 2019 i3.

Along this line, does anyone know if the replacement 60 Ah pack from BMW is of an updated or different make/design/chemistry which may makes it less susceptible to degradation than the original pack?

 

[alohart]

Along this line, does anyone know if the replacement 60 Ah pack from BMW is of an updated or different make/design/chemistry which may makes it less susceptible to degradation than the original pack?

BMW could even be building warranty replacement battery packs using 60 Ah cell modules from used battery packs that they've tested and matched for capacity. The resulting battery pack would need to have more than 70% of the nominal new usable capacity, but that's about it. Apparently, that's what Honda did when it replaced many 1st-generation Honda Insight battery packs due to poor or no automatic cell charge level balancing, especially after 2006 when the last Insight was manufactured. After a while, it becomes difficult to buy the same cells new.

I wonder whether Samsung SDI continues to manufacture the 60 Ah cells that were used in 60 Ah i3 battery packs. Samsung SDI has moved way beyond such low-capacity cells and might not still be manufacturing them. Lithium ion cells degrade with age, so storing a bunch of them for future use would result in cells that have lost capacity by the time they were used in a battery pack.

 

[Marscar]

Have you read of any 94 Ah or 120 Ah battery pack losing more than 30% of its original usable capacity? I haven't. These battery packs seem much more resistant to capacity loss than many 60 Ah battery packs. Unlike when we owned a 2014 i3, I don't worry at all about capacity loss in our 2019 i3.

BMW may well have improved their act but I wonder whether also the simple fact of the larger battery needing, in effect, less cycles for the same amount of driving is a factor?

 

[Neil]

$30k? How'd you get such a deal? My quote was for over $40k.

 

[alohart]

BMW may well have improved their act but I wonder whether also the simple fact of the larger battery needing, in effect, less cycles for the same amount of driving is a factor?

That's certainly a valid factor. However, at only 12k miles, our 2014 i3's battery pack hadn't experienced very many charge-discharge cycles yet had lost ~25% of its capacity. Having been driven 33k miles, our 2019 i3's battery pack has experienced more charge-discharge cycles than our 2014 i3 had experienced yet has lost no more than 4% of its usable capacity.

I understand what causes lithium ion battery cells to degrade and always strove to do the right thing. My conclusion is that some, but certainly not all, 60 Ah battery cells degraded rapidly for some reason, possibly due to poor quality control.

 

[Neil]

Does anyone imagine that a class action suit regarding the 60Ah battery issues would have any merit? Any lawyers out there to chime in? Asking for a friend.

 

[Gonville]

That's certainly a valid factor. However, at only 12k miles, our 2014 i3's battery pack hadn't experienced very many charge-discharge cycles yet had lost ~25% of its capacity. Having been driven 33k miles, our 2019 i3's battery pack has experienced more charge-discharge cycles than our 2014 i3 had experienced yet has lost no more than 4% of its usable capacity.

I understand what causes lithium ion battery cells to degrade and always strove to do the right thing. My conclusion is that some, but certainly not all, 60 Ah battery cells degraded rapidly for some reason, possibly due to poor quality control.

Did the 60ah get charged to 100% to enable cell balancing? This is what happened to mine 2014 when I only charged it to 80%

 

[alohart]

Did the 60ah get charged to 100% to enable cell balancing? This is what happened to mine 2014 when I only charged it to 80%

The mi3 app showed that the voltage and capacity ranges of all 96 battery cells were very nearly identical which would not be true if cell charge level balancing had not completed. Besides, passive cell charge level balancing occurs at charge levels less than 100% although probably a bit more slowly because of slightly lower cell voltages. I don't know whether there is a charge level below which cell balancing doesn't occur.

Did you meet with BMW engineers in the U.K. shortly after the i3 was introduced? I recall reading that this i3 owner feels that cell balancing occurs at a charge level as low as 80%.

I know of 4 other local 60 Ah i3 owners whose battery packs were replaced under the battery pack capacity loss warranty. These owners drove and charged in a variety of ways yet the usable capacities of their battery packs decreased more than 30% within 8 years. We all live on an isolated island in which the longest round-trip drive is less than 120 miles, so these i3's were not high-mileage vehicles. My conclusion is that there must have been some weak 60 Ah battery cells, maybe due to poor quality control.

 

[Djsvideo]

Before you go to the dealership, download the free app
mi3 for iOS iPhone or iPad.
You can check the HV battery capacity & SOH also the Rex use.

Excellent app

 

[alohart]

Before you go to the dealership, download the free app
mi3 for iOS iPhone or iPad.
You can check the HV battery capacity & SOH also the Rex use.

Excellent app

The "electrified" app for Android reports similar data.

However, the capacities, SOC, and SOH data reported by both apps are just calculated values that are subject to the same variability and inaccuracy as the Batt. Kapa. max values displayed in the hidden service menu. They do have value in displaying the minimum and maximum cell voltages which could help determine how well the cell charge levels are balanced.

 

[Gonville]

The mi3 app showed that the voltage and capacity ranges of all 96 battery cells were very nearly identical which would not be true if cell charge level balancing had not completed. Besides, passive cell charge level balancing occurs at charge levels less than 100% although probably a bit more slowly because of slightly lower cell voltages. I don't know whether there is a charge level below which cell balancing doesn't occur.

Did you meet with BMW engineers in the U.K. shortly after the i3 was introduced? I recall reading that this i3 owner feels that cell balancing occurs at a charge level as low as 80%.

I know of 4 other local 60 Ah i3 owners whose battery packs were replaced under the battery pack capacity loss warranty. These owners drove and charged in a variety of ways yet the usable capacities of their battery packs decreased more than 30% within 8 years. We all live on an isolated island in which the longest round-trip drive is less than 120 miles, so these i3's were not high-mileage vehicles. My conclusion is that there must have been some weak 60 Ah battery cells, maybe due to poor quality control.

We think the level at which cell balancing doesn’t happen is 85%.

Yes I did meet with engineers in UK - we had a mega meet at Farnborough BMW HQ. Was very informative. Pictures I took at that session are in David Bricknell’s excellent book.

I suspect as we have had only 1 or 2 documented pack (modules not complete) replaced in 10 years there is a lot on the temperature.

I am assuming your island has some very nice temperatures compared with out ‘islands’? LEAF in Arizona same sort of issues?

 

[Gonville]

I don't know whether there is a charge level below which cell balancing doesn't occur.

Did you meet with BMW engineers in the U.K. shortly after the i3 was introduced? I recall reading that this i3 owner feels that cell balancing occurs at a charge level as low as 80%.

Yes I believe BMW told us at that meeting that it was around 85% indicated. They didn’t want to impact range on the very small battery below that level. We have used that ever since although I have never found that identified in any workshop manuals.