Traction battery going bad or something else?

[RobbW]

I have a 2012 iMiEV SE. I bought it in July 2013, and it currently has 43,000 miles on it. Up until this past Sunday, it has charged fully (16 out of 16 kWh bars and around 70 miles +/- of RR) every time I have allowed it to charge until full. The Friday after Thanksgiving, we went on a mini vacation out of state for the weekend. We drove our Pacifica Hybrid and left my Meepster at home unplugged. Sunday night when we got home, I plugged the Meeptser into the Leviton L2 EVSE in our garage to make sure it was fully charged and ready for my work commute on Monday. The next morning, I came out to drive to work and found that the Meepster had only charged to 75% (only 12 out of 16 kWh bars and 40 miles RR). Confused as to how this happened, I drove to work and plugged it into the Chargepoint L2 EVSE at work.

During the workday, I received the automated text message from Chargepoint letting me know that my vehicle had completed charging. At the end of the day, I went out to my car to find it once again had only charged 75% (12 out of 16 kWh bars and 40 miles RR). I drove home with the heat on and got home with about 4 kWh bars remaining. I plugged in at home and let it start charging immediately instead of putting it on the schedule.

A couple hours later, I checked in on the Meepster and saw that the charging light on the EVSE was green indicating my car was fully charged. That was odd because it should have taken much longer than that to fully charge. I pressed the "Send" on the remote to check the charge status, and it showed only 2 out of 3 bars. I unplugged my Meepster and plugged it back in to see if it would start charging the rest of the way. It initially made the loud click and the fan noise usually associated with charging, but the EVSE then clicked off after about 10 seconds. I tried unplugging and replugging a couple more times to no avail. At this point, I left it alone assuming I was going to have to call the dealership in the morning to make an appointment.

Just before going to bed, I took my keys out to the Meepster and turned the ignition to the "On" position so I could check the miles on the odometer because I wanted to include that info in this post. After getting the miles and turning the car back off, I decided to try unplugging/replugging one more time just for the heck of it. This time, the charging light stayed on and the car made all the different noises usually associated with charging. The EVSE kept the charging status light on for the entire 5 minutes I was standing there watching it. I assumed that whatever issue my Meepster had been having with its charging system must have cleared up by me turning the car on while it was plugged in. I went to bed hopeful that I would have a fully charged iMiEV in the morning.

This morning, I went to go to work and found that my Meepster, once again, was only showing 12 out of 16 kWh bars charged and only 40 miles of RR. Grrrrrrr!!!!!

I am now at work and will be calling the dealership to make an appointment to bring my car in. I figured I would post here first to see if anyone has any suggestions or recommendations on things I could checked to hopefully clear up this problem. Or is this definitely something only the service department at the dealership is going to be able to fix? This certainly does not seem like the normal and expected battery capacity degradation that is mentioned and warned about in the owners manual. If the Meepster still fully charged to 16 kWh bars but was steadily getting fewer miles on a full charge, then I would assume it was the expected battery degradation. However, this situation is my car suddenly not even fully charging to the 16 kWh mark! I assume this must be indicative of bad cells in the traction battery, right? Or is there something else that might cause this? It's definitely not my home EVSE as this is happening on my work's EVSE, too.

 

[RobbW]

Okay, so I found the thread below from another owner in Australia who sounds like he experienced the exact same issue I am having. I didn't see that thread until after I posted. I'm sorry for posting a new thread on the same topic, but I was just trying to quickly get my issued posted (and hopefully some responses from you great folks) before I called the dealership to make an appointment. I've only read through page 1 of 6 so far but will now continue reading the rest of the thread to see if there was any satisfactory remediation. Thanks!

http://myimiev.com/forum/viewtopic.php?f=23&t=3718

 

[kiev]

Sounds like you are having the same issue that i have right now--a weak cell in the battery pack. See this

http://myimiev.com/forum/viewtopic.php?f=23&t=3877&p=34447#p34447

 

[iDriver]

Greetings. I would recommend taking it to the dealership and getting the battery replaced under warranty right away. I say that, because that's what I had to do! This was a little more than a year ago. The car had 50k+ miles on it, and was purchased in Jan of 2012. I'm not upset about this, because that's what a warranty is for, and I knew the risks with being an early adopter.

Yup, new pack for me. I had 2 Cells that would drop out and cause the Turtle to pop out whenever the car was under load. First started having the issues via Up Hill climbs. It took the dealership more than a month to actually figure out what was going on, but they eventually did. (I actually showed them the CanION app and road with a tech in the car so he could see the data. They were very impressed!) I learned my lesson on that one and now i take the car to another dealership, they know how to work on the i-MiEV and all is good.

 

[RobbW]

I have an appointment to drop the car off at the dealership tonight. They will have it all day tomorrow to do whatever inspections and testing is required.

For those who had similar issues and took your iMiEV in for warranty repairs, did the dealership give you any hassles about not following any sort of maintenance program in order to keep the vehicle under warranty? The dealership I bought my Meepster at did not give me any sort of warranty-required maintenance program I had to follow at the time I bought my car. Nor did they mention any required maintenance in the several times I have taken it back to the dealership for recalls or other miscellaneous issues. I am concerned, but only slightly, that they may try to balk at replacing the battery pack under warranty and give me some excuse about not following the Mitsubishi required maintenance program (whatever that program may be, if there is such a thing for the iMiEV).

 

[RobbW]

Update:

Dropped my Meepster off at Bigger's Mitsubishi in Elgin, IL last Tuesday night, Nov. 28. Didn't hear from them until late afternoon on Thursday. The verified that they have duplicated the problem I am having with charging up to only 12 out of 16 bars. They said they had spent the last two days fully depleting the battery and then fully recharging with the same results.

The service manager said he was working with Tech Engineers from Mitsubishi to identify the problem and the est solution. He said the tech engineers sent him a huge questionnaire that he had to ask me so they could figure out what they were going to do. Took about 10 minutes to get through the questionnaire. It was all questions about my driving and charging habits. I'm sure they're just trying to CYA and see if there is a way to get out of having to pay for a full warranty replacement.

Anyway, they sent my answers off to Mitsu, and I didn't hear anything more until yesterday afternoon. I called the service manager because I wanted an update and needed to find out how long it's going to take because I needed to make alternative transportation arrangements. Luckily, they told me to come in that evening, and they would give me a loaner car.

The service manager explained that they had run several more diagnostic tests and determined that the main battery pack has a bad cell that is under-performing compared to all the other cells. They were planning to hook my Meepster up that night to perform a "smoothing" operation that may or may not help bring the bad cell back into proper specs. He told me he is still waiting to hear a final determination from the tech engineers at Mitsu as to whether it's going to require a full battery replacement. During both times I spoke with him on the phone, he kept mentioning just how expensive the main battery is if it needs to be replaced. It was almost like he was subconsciously trying to make me feel guilty about it. I assumed that any warranty repairs are fully reimbursed to the dealership by Mitsu, but is that not the case? Is the dealership also on the hook for a portion of the warranty replacement?

Anyway, the service manager explained that he has to wait for final word from the tech engineers. He can't even go ahead and order the new battery even if he wanted to. In fact, he explained that he has no control over that process whatsoever. That if a battery replacement is authorized, Mitsu will just ship it right out to him without him even having to order it or anything. They will also have to send out all the tools and specialized equipment for lifting and installing the battery pack.

That's all I know for now. I'll update again when I hear anything more. In the meantime, I'm driving around in the Outlander Sport (ICE) they're letting me use. This is a really weird feeling driving a fully-ICE vehicle again. Now that our family is an all EV/PHEV family, I am noticing all the peculiarities of ICE cars that I never noticed before!

 

[JoeS]

RobbW, thank you for the update.

So far, Mitsubishi has been very good about replacing battery packs which exhibit the problem you're experiencing.

To me it's unclear whether that single cell problem is a defective cell (most probably) or the BMS as it applies to that cell.

For Mitsu, it is an expensive process as they ship the replacement pack to the dealership with all the special equipment to remove/replace the pack.

We have had at least one member successfully replace a defective cell in his pack - Martin (me68), developer of CaniOn. detailed in this thread:
http://myimiev.com/forum/viewtopic.php?f=23&t=2720&

Replacing an individual cell with one of similar capacity to the rest of the pack is another variable - to me, off the top of my head I don't see why a 'better' cell would necessarily be a bad thing, recognizing it is a series string of 88 cells.

This is quite a dilemma for Mitsubishi, as, although the cell replacement itself is fairly straightforward, the technician education and OSHA constraints when working with high voltage are formidable enough that only pack replacement at dealerships is presently viable.

RobbW, based on my and others' past experience, Mitsubishi will take care of you. In the mentime, have fun driving your poison-gas-spewing ICE loaner.

 

[kiev]

i would be very interested to hear the results of the "voltage smoothing". i have a low cell and went to the dealer to ask if they would perform this on my car, but they said the discharge and charging procedure would have to be done a couple of times and then they talk to Mitsubishi and do what they say. i've already charged numerous times and i have cell data from two different sources that show which cell is low--i'm sure they could verify that if they knew how to command the MUT to read the cells.

In the meantime i bought a copy of the MUT software and have a laptop on which to run it. The missing link to having my own MUT is the VCI box--vehicle communication interface, which connects to the OBDII port on one cable and to the PC over USB. There are many of these found on ebay but they don't seem to really have the full programming capablilty. The i909 from icarsoft will do everything except programming also, and it is much less expensive--but i don't need another data-reader, i want all the functions so i can do cell smoothing on my own time...

 

[RobbW]

The service manager at Bigger’s Mitsubishi just called me. Mitsu is going to go ahead and replace the main drive battery. He said they have the battery packs in stock at their facility in Atlanta. Normally, it would only take a couple days to get them delivered. However, the issue is the lifts and special equipment that are required to replace the battery. He said that Mitsu USA only has 5 sets of the specialized equipment in the entire country, and right now, they are all out to other service departments. So, it may take a week or a week and a half to get the equipment. He will update me once they get the tools and the battery.

So, bad news is that it’s going to be a couple weeks before I get my Meepster back. Good news is that I'm getting a brand new battery pack! So, it’s basically like getting a reset on the life of the power train of the car!

Unfortunately, he never mentioned anything about the results of the smoothing operation. So, I cannot provide any further details on that. Suffice it to say, the results were not positive.

 

[RobbW]

Anyone know if replacing the main battery pack resets the warranty on the battery? Or do you only get the remaining life of the warranty?

 

[Aerowhatt]

Anyone know if replacing the main battery pack resets the warranty on the battery? Or do you only get the remaining life of the warranty?

As with most warranty replacements, or repairs you only get the remainder of your original warranty on the new traction battery.

Aerowhatt

 

[Aerowhatt]

The i909 from icarsoft will do everything except programming also, and it is much less expensive--but i don't need another data-reader, i want all the functions so i can do cell smoothing on my own time...

Cell smoothing may also include charging to a higher voltage. But certainly it's main function is to enhance the balancing function. As you stated previously the balancer function has a very small power "bypass" making the amount of balancing per full charge pretty small. That's part of why I advocate frequent charges to 100% SOC (but that's another conversation).

You can increase the balancing function time per full charge without much in the way of equipment. What ends the charge while balancing is the highest cell(s) tripping whatever the high voltage limit on the BMS is. That's why a full charge to 100% on 8 amps of 120 volt AC will give you a longer more effective balance than a faster charge at higher power. The balancer bypass on the high cells is a larger percentage of the total amperage fed to the pack. So it takes longer to trip the end of charge and lower cells catch up more.

Taken a step further. With Canion you can see just what is going on with a charge cycle. So using it, you can use the power used by accessory drains to pull down the charge current to the main traction pack. Thereby significantly holding off the end of charge signal from the highest cells. The charger in the car can only produce a fixed amount of power based on what is supplied to it. By sending the right amount of this power to the DC converter to run lights and cabin fan etc. A single end of charge balancing cycle can be drastically extended by only providing to the traction pack for charging approximately what the balancers can bypass. This will provide a similar activity to whatever the voltage smoothing cycle is that the dealer can do with their programing equipment.

Aerowhatt

 

[kiev]

The only way i can see for smoothing to be effective is to turn on all the balancers except for the lowest cell and try to bleed them down to the target value. This could be done at any SOC while the car is stationary and not charging.

If there were any charging currents greater than 0.1 Amps, then the cells would continue to be charged even with bleeders on.

 

[adam]

Anyone know if replacing the main battery pack resets the warranty on the battery? Or do you only get the remaining life of the warranty?

I called today and the dealer don't know if the new battery pack is brand new or refurbished. He confirmed that the warranty period is not reset though.

 

[phb10186]

Anyone know if replacing the main battery pack resets the warranty on the battery? Or do you only get the remaining life of the warranty?

I called today and the dealer don't know if the new battery pack is brand new or refurbished. He confirmed that the warranty period is not reset though.

This question has come up before, and essentially, no warranty would be reset by a replacement part/ product, it's effective from the purchase date of the vehicle (all warranty terms are somewhat different, but it's almost always from the date of purchase/ delivery).

RE: whether the packs use recycled cells or not, that's also been debated, but who knows. It would certainly make sense on cost and environmental grounds to not dump the entire pack for one or two bad cells... They are going to need a couple of packs at the ready for dispatch at all times to cover failures in-warranty, but who knows what processes are happening behind the scenes, RE cell reuse to the point packs are made for dispatch. Seeing as there is no common source of used cells for our cars, I would assume some that pass specific test marks are reused, and those that are not are destroyed, but there would be no way to know that. It's as probable that they are all new, as it is that some are re-used... i'd like to know the answer to that question though.

Does the ah/h quoted on the recently replaced new pack on the other post equate to 88 brand new cells... anyone?

Lastly, does anyone know if there have been any other pack replacements for items other than bad cells - i.e. circuitry - I've always thought that one of the balancing boards could fairly easily get a dry joint and pack up...

 

[Don]

It's only been a short time that we end users have had a way to measure capacity. I think most who have measured replacement packs are reporting 44 or 45 Ah - Who knows what the supposed 50 Ah packs actually measured when they were brand new?

I would *assume* that replacement packs are put together using used cells - Why would they even consider using brand new ones when more than half of the warranty is already expired and they only need the replacements to last another 4 years or so . . . . ???

One could even make the argument I think that a replacement made up of well tested cells with 10 or 15K miles on them might actually be less likely to fail than a brand new pack

Don

 

[kiev]

i remember reading in the service manual that the old battery pack is flooded in a bath of salty water before being sent back--a safety measure for shipping. So i don't believe that any are remanufactured.

To get 50 A-Hrs from a new cell requires discharging to 2.75 volts after charging to 4.1. Mitsubishi doesn't let them discharge that low, so nobody will ever see a value that high.

 

[Aerowhatt]

The only way i can see for smoothing to be effective is to turn on all the balancers except for the lowest cell and try to bleed them down to the target value. This could be done at any SOC while the car is stationary and not charging.

If there were any charging currents greater than 0.1 Amps, then the cells would continue to be charged even with bleeders on.

My "guess" is that the balancers "bleeders" are locally controlled by the module BMS board based on individual cell voltage values. I've never seen a BMS system that works any other way. It's significantly more complicated to centralize it more than that. In smaller applications, I've dealt with, dissected, studied, and learned to trick BMS circuits of many stripes over the last 12 -13 years. By reducing the charging amperage we could always get the "bleeders" to run 3 to 20 times longer before a BMS initiated charger disconnect.

Newer BMS systems can also include a minimum amperage charge rate to continue charging, which complicates the process of "voltage smoothing" by this lowest possible charge rate method.

Mitsu installed a very low amperage Balancing circuit in their battery BMS. Or perhaps better stated, Yuasa did. They also did not include the ability to set the car to stop charging at less than 100%. The implication is that that frequent 100% SOC charges are best for maintaining cell balance. My own experience with the cars battery packs, supports this assumption. The older a pack is, the faster it will drift out of balance. Individual cells age differently, so cell efficiencies diverge over time resulting in greater variations over time and cycles. The least efficient cells are less efficient on both discharge and charge cycles, further exacerbating any disparity.

If there is evidence that the Yuasa BMS works differently than others, I would love to see it! A floating target, or bleeder initializing voltage would be a huge improvement. I suspect that Tesla may have this built into their BMS.

Aerowhatt

 

[RobbW]

Got an email from the service manager this morning. They have received the new battery pack for my Meepster, but they are still waiting on the specialty lift and tools required to install it. He said normal the tools would arrive first. He hopes they will have them within a few days.

 

[RobbW]

YEA!!!!!! Three weeks to the day from when I dropped my Meepster off at the dealership, she is back! Picked her up from the dealership last night. When I unplugged this morning before my commute into work, she was showing a full 16 bars and 79 miles RR with 42,977 miles on the ODO. Outside temp was 29°F this morning, but I did not use the heat on the way in. I preheated while still plugged into L2 charger in my garage, and then only used the seat warmer during the drive. Parked at work with 14 bars remaining, 67 miles on the RR, and 42,989 miles on the ODO. So, in sub-freezing temps without using the heat, she matched mile-for-mile the RR to the ODO. I used up 12 miles of RR for 12 miles of actual distance. Not too bad for this weather.

We're an all-Apple family. So, I don't have an Android device conveniently accessible to check any stats on CanION. If I can locate an Android device, I'll see what kind of data I can pull with regards to battery/cell stats. For now, I'm just happy to have my Meepster back and working properly.