Mitsubishi on Capacity Loss

[JoeS]

In a post from Don in a different thread -

The basic argument is that if the battery fails to live up to its published specifications by some degree, then you have abnormal degradation.

For warranty purposes, what 'degree' would be considered 'abnormal'? Hard to press for any replacement unless there's a definitive 'line' and you have proof that your claim has crossed that line

I guess not everyone got the indoctrination we got when we bought our first car new in May of 2012. They (a dealers representative trained in this aspect of car delivery) sat us down and explained that the car is battery powered and that the battery will degrade as it ages, by an expected (but not guaranteed) 20% or so over 5 years and that the degradation *was not covered by warranty* and then they had us sign a form saying we had been properly briefed on the battery warranty - Battery degradation of any amount was not covered by the warranty - Only 'defects' were covered. No mention of 'abnormal degradation' at all . . . . in fact, the opposite claim was made - Degradation is normal

I just don't see where anyone, anywhere would have an enforceable claim that their battery is 'failing to live up to specifications by some degree' if it still charges to 16 bars and will move the car down the road 20 miles or more - We may not like it, but we weren't promised anything more

On the other hand, iMiEV's are not Nissan Leafs - Our batteries, by and large, have not had the problems Leaf owners experienced and the batteries have performed better than we were led to expect

Don

Further supporting Don's comment, I dug up my original paperwork that I signed when I purchased my i-MiEV brand new in February 2012, and here is a partial excerpt from the applicable paragraph -

E. Gradual Capacity Loss

The capacity of the Main Drive Lithium-ion Battery on your "i", like other commonly used Li-ion batteries, will decrease according to time and usage. This type of decrease in battery capacity is normal and not indicative of any defect or failure in your Main Drive Lithium-ion Battery. As the Main Drive Lithium-ion Battery capacity decreases, the initial cruising range of the vehicle will similarly decrease.

• Mitsubishi Motors estimates that after 5 years, the capacity of the Main Drive Lithium-ion Battery provided with your vehicle will be approximately 80% of the original capacity. After 10 years, the capacity should be approximately 70% of the original capacity. These are only estimates, and the actual capacity of your vehicle battery over time will depend on a variety of factors including how your vehicle is used, stored, and charged. Factors that can adversely affect battery capacity over time include frequent driving using aggressive acceleration/deceleration, repeated frequent use of the quick charger, and operation/storage in extreme temperature environments
...

There are many posts on this forum, especially those in the early days, where many of us were attempting to zero-in on the proper care and feeding of our battery pack in order to maximize its longevity. I'm happy to say that in my case this has hopefully resulted in the negligible reduction in the range of my original i-MiEV (which I sold to friends in December but still keep tabs on) with over 50K miles, and neither of our present two i-MiEVs (purchased used) exhibit any noticeable range loss (recognizing that one had a new battery put in a couple of years ago for an outright cell failure).

Mitsubishi's technique is to not display capacity loss on the fuel gauge; instead, they initially merely reduce the amount of invisible "reserve" capacity which, if you will, simply reduces how far you can drive after the fuel gauge goes to zero. Having never been there, I can't comment on that aspect. I fully expect my range to visibly diminish over the next few years.

My own rule of thumb is that in normal driving eight bars on the fuel gauge approximates RR=32 miles. After five years, I simply haven't seen that change noticeably. When the time comes in the future and I do experience that 20%-30% capacity loss, I'm comfortable knowing that I will be able to continue driving my i-MiEV normally, since on a daily basis I rarely charge over 12 bars.

 

[Carsten]

I have a 2012 SE, bought new in 7/2013, that has now a tad more than 70,000mi on the odometer. Until mid of last year I could easily go 70mi on my round trip to/from work. 3 of my cells went much worth over the last mild winter in MD and I now get barely over 55mi round trip out of it.
I went to Mitsubishi, they checked the battery and told me, that I have about 40% loss. Initially, they wanted to get the pack repaired/replaced, but called me back 1 day later and told, they would only honor the warranty, if the pack would fail.
Here is me, hoping for at least 1 cell to go belly up.
I use the DC-charger maybe once a month.
I still get to 16 bars, when fully charged.
Has anybody here any experience in getting a warranty claim out of Mitsubishi in that sort of situation?
Any advice would be greatly appreciated.
Regards,

 

[jray3]

That's a bummer, Carsten. I'm also just past 70k miles and still seeing a lot of 81 RR mornings and no noticeable performance decline. For the good of the order, this could be a good time to get a price quote from Mitsu on a non-warranty battery replacement...
Thanks,
Jay

 

[phb10186]

Mitsubishi UK are suffering their own capacity loss: on the warranty itself. Only 5 years on all parts, so my '12 is now out of battery warranty as of March - and even though I asked them if they had plans to increase it to 10y - and they said yes last year - they never actually did it.

As far as battery degradation goes, im not sure how correlated capacity loss is from cell failure - as my chemistry tells me that failure is likely due to the membranes that separate the anode and cathode , and gradual loss is likely to do with the lithium paste side of the cell essentially oxidising/ going hard or dry - that sort of thing. Though I can see a correlation in normal capacity loss and premature failure, I wouldn't be surprised if they are not that well correlated - one being chemistry related, the other being manufacture.

I've had genuine Samsung batteries for my phone fail while they retain a good residual capacity, and others dying slowly - which tells me that one is a manufacturing problem, while the other is chemistry. It's easy to convince yourself that a barrel cell with a metal case and core would be more robust than a flat envelope type cell. If you consider a laptop or phone battery, they are constantly in a state of charge or drain, and they tend to last about 2y, but with a car, they are not, likely only used 1-2h per day, so if you do the maths it tells me about 8-10 years would be the uptick in service end. The late failures I think we are yet to see, but we do now have a rough idea of early failures, and it would appear to be one in several hundred over 5 years, which is pretty good if you think about ICE cars. Difference of course is that with an electric car out of warranty, its unpredictable and catastrophic when it does occur.

Toyota, the leaders of TPS and Lean manufacturing (and there are few to touch them) use the 5 year failure rate data as the basis to design out imperfections - so I have tended to adopt that benchmark for my considerations. In fact, they have a screen through production lines showing workers data, and one of the metrics they show is the failure rate at 5 years ago today.

I was also thinking that we go on and about charging habit, but is there any chance that the on-board charger could actually play a part too, with those being the cause in some cases?

 

[zzcoopej]

If you consider a laptop or phone battery

I think the biggest factors differentiating laptops and phones from EV are battery temperature and average SOC. Its almost impossible to control cell temperature in a phone or laptop, other than shut off charging when cells get too hot. SOC in a laptop often sits at 100% which is also not good, whereas in an EV the battery is sure to be cycled and therefore not sit at 100% SOC for long.
My iMiEV is now 6 years old, longer than any phone or laptop battery has lasted.

 

[kiev]

Thinking about the mechanism for a charger-related failure--would it be an overall pack degradation due to repeatedly overcharging?

If so, then is it an algorithm issue (programmed at too high cut-off voltage), or a sensor/measurement issue?

 

[Don]

SOC in a laptop often sits at 100% which is also not good, whereas in an EV the battery is sure to be cycled and therefore not sit at 100% SOC for long.

Hopefully, neither the laptop nor the EV are actually charging their batteries to 100%

Don

 

[Carsten]

All,
I have an update on my MiEV:
2 days ago on my way home I all of a sudden lost power and the car would only drive like in E-mode with a maximum of around 30mph on a flat road. I ahd 54mi of range left and the display showed the yellow RBS-, car!- and ABS Off-sign. When I tried to accelerate, the turtle-sign would come on. I limped to a Mitsu-dealer and he couldn't read anything out of the OBD2, it simply said, that it can't connect. I had charged there for a bit, whilst waiting. When I left the dealer, everything was back to normal. The next day I had business close to my normal Mitsu-dealer and I popped in to have them look at the issue again. They found 11 different codes, all related to the MCU. Clearing them all was possible but 2 of them come back all the time. They were in contact with Mitsu-Central but couldn't solve it all day yesterday. They kept the car and I told them to look again into my lost range (40% battery capacity loss, according to a verbal statement of my mechanic) whilst they work on the codes. I have 70,900mi on my 2012 MiEV SE, bought in 7/2013.
Here is me with mixed feelings:
- hoping for Mitsu to fix both issues and
- hoping for Mitsu to come back with a partial payback due to cost of warranty repair.
I'm located in MD.
I will post updates.

I love the simplicity of the MiEV and if I would have the initial range again, I would not trade it for a newer EV.

 

[Carsten]

Update on my MiEV:
The dealership called me and wants to keep the MiEV and drive it for as long as it takes to replicate the issue. They put a recording device on it and have a mechanic drive it every day.
It took 71,000mi to have the event once, I just hope, that it doesn't take that many miles again.
I don't know, if I should laugh or cry.

 

[JoeS]

Carsten, thank you for continuing to keep us up to date. Can't help but wonder if the degradation you reported a month ago hasn't something to do with the issue you're seeing; i.e., a few low cells being strangely interpreted by the BMU. In any case, hope Mitsu pinpoints the exact problem. Oooh, wonder what sort of a 'recording device' they put on the car, as something like that could be of value to us in the future?

All the best to you.

 

[Carsten]

I will see, that I get info on the recording device.

 

[phb10186]

Update on my MiEV:
The dealership called me and wants to keep the MiEV and drive it for as long as it takes to replicate the issue. They put a recording device on it and have a mechanic drive it every day.
It took 71,000mi to have the event once, I just hope, that it doesn't take that many miles again.
I don't know, if I should laugh or cry.

I would say laugh, but seeing as they have 11 codes to go off, they should be more than capable of identifying the unit at fault without driving a single yard... so i'd cry.

Yet more examples of poor diagnostic processes built on flawed diagnostic algorithms. So far, Toyota are the only company that I say are actually capable of adequately diagnosing faults on their vehicles properly and quickly. Reliability and fault rectification is what I believe separates out the good manufacturers from the bad... and almost all are bad. Easy to shove a car out of a factory, but much harder to supply the technical support down the line when real-world issues occur.

 

[kiev]

Did they give you a list of the 11 trouble codes and/or the 2 that won't clear--maybe we could do a little de-coding and start a wager-pool on the final culprit...

 

[Carsten]

It gets more interesting. I had a message from the dealer on my phone today, that the mechanic found a rapidly deteriorating range on my MiEV. Duh - I was at the same dealership about 2 months ago and told them, that my range went drastically down over winter and never came back in spring. They checked it and I lost 40% from a new battery(at 70,000mi), but it was not a reason for a warranty claim. They recorded the drive, sent it to Mitsubishi USA today and maybe now it is one.

 

[kiev]

@Carsten, Any updates or status to report on this?

If the car still charges to 16 bars then they may not consider it a defective pack. If a cell is weak or defective then charging will stop before the gauge shows the full 16.