Is my battery dying ?

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Simon,

Thanks for all your data and investigations.
Do you have any information on the temperature of the batteries?
Despite our mild climate, heavy use and rapid charging can heat up the cells and on a few wintery days, I have rapid charged which has heated up the battery and increased the range.

I haven't yet got canion as I think it would give me a bad case of battery degradation anxiety. :(

My RR display has lots of variability too despite my drives, conditions and driving style being fairly consistent. How exposed are the roads that you are driving on?
As we both live in "the windiest country in Europe", the wind can have a massive impact on the range especially at higher speeds.
I have noticed that wind seems to be the biggest factor in my range. I also do a lot of driving on 70mph dual carriageways. If I keep the power meter under 1/3 of full power my speed varies from 50mph to 70 mph and slip-streaming a bus can make all the difference :mrgreen: .

My car is the same age as yours and I am interested in the response from peugeot. If this warranty information is correct, I have just under a year's warranty on the battery.


Happy driving.
 
DBMandrake said:
The precipitous drop is out of character for the car, and after reading many other threads here that started with similar concerns and ended up with a battery pack replacement under warranty due to a rapidly dying cell, I'm naturally quite concerned.

Especially when I still have 3 years of personal bank loan left to pay off the car - if it gets written off due to a faulty battery not covered under warranty I'm in the awkward position of either trying to source an individual cell and fit it myself (which I could do with access to a hoist, but it's a big project - I have the knowledge but not really the working facilities to do it) or having to continue paying for a car for several years that is now scrap and off the road... :(

....

Keep in mind that my car is a 2011 - which means it has the older LEV50 cells, not the newer LEV50N from 2012 on which supposedly degrade at a much lower rate.

Does anyone know if the LEV50 cells are interchangeable with the LE50N's?
I would like to keep my car on the road as long as possible even if it means having to replace cells.
I notice there are some LEV50Ns for sale here -

https://www.ebay.ca/itm/Mitsubishi-I-Miev-lithium-Ion-battery-cell-module-50AH-Tesla-Nissan-Leaf/292501482394?hash=item441a726b9a:g:438AAOSwRTVaaqha&vxp=mtr

I've contacted the seller to see if he can literally ship it from canada to the uk - don't think airlines like flying with large batteries! And shipping regulations seem to be increasingly tight.

I also stumbled upon this article --
https://pushevs.com/2015/11/04/gs-yuasas-improved-cells-lev50-vs-lev50n/

14.5kwh vs 16kwh! An interesting read...

Simon, I just noticed your battery temp on canion and presume that you probably don't quick charge as much as me!! :eek:
 
Shipping Yuasa batteries by air? That ought to go over well :lol: ;) (Dreamliner incident?).

In all seriousness, though. DBMandrake, per your signature, your car is a 2011. When most of us here in the States bought our cars, there was an addition to the owners manual after it was printed in the form of an orange paper, stating that a change in the car's software made it so that a balance charge was activated when charging was initiated at 2 bars charge or less. Do earlier versions of the car (2009-2011) have this feature?

LEV50 and LEV50N cells should work fine together as charge and voltage profiles are the same. There were some internal changes that made them a bit more efficient and hardy to extreme temperatures.
 
PV1 said:
Shipping Yuasa batteries by air? That ought to go over well :lol: ;) (Dreamliner incident?).

Yup, they don't seem to literally ship anything anymore! ;)
Li-ions can travel on cargo air only. So, provided, the paperwork is complete - should be no problem. Seller is getting back to me as unsure about which forms to be filled in..
If anyone else located in the UK/EU is looking, I can order extra cells to save on postage/customs.
Good to have a few extra cells :D

PV1 said:
In all seriousness, though. DBMandrake, per your signature, your car is a 2011. When most of us here in the States bought our cars, there was an addition to the owners manual after it was printed in the form of an orange paper, stating that a change in the car's software made it so that a balance charge was activated when charging was initiated at 2 bars charge or less. Do earlier versions of the car (2009-2011) have this feature?

For some reason I remember they do.... /Checks/
Yes it does. Found my pdf copy of the 2011 i-miev user manual. It states:

"It is recommended that you perform regular charging from 2 bars or less on the energy level gauge to full at least every three months. This lets the energy level gauge adjust to decreases in battery capacity and correctly show the remaining energy in the main drive lithium-ion battery."

This is something I have not done in a while - On most of my longer trips, I quick charge to 80% or L2 charge for an hour or so. I end up with 3-5 bars remaining when I arrive home. The car gets charged to full bars on L2 at least once a week. Trying to make my cells last as long as possible. Lowest battery has been is 1 bar and when I connected to the quick charger, it rated the battery at 18%. Haven't tried canion yet as it will just give me degradation anxiety. I was under the impression that the car periodically does battery balancing when charging on L1/L2 and always when charging from 2-16 bars.
See this post
http://myimiev.com/forum/viewtopic.php?f=23&t=270&start=10

Now I'm scared to run down to 2 bars and back to 16. May significantly reduce my RR gauge - although I know it will not make any difference on the actual capacity! :shock:
 
Luddite said:
Do you have any information on the temperature of the batteries?
Despite our mild climate, heavy use and rapid charging can heat up the cells and on a few wintery days, I have rapid charged which has heated up the battery and increased the range.
I've been keeping an eye on battery temperatures (especially in light of the Leaf 2 "Rapidgate") and they are very low, at least at this time of year.

My 38 mile commute to work and back has yet to raise the temperature of the cells above 17C - typically they start around 11-14C and end up at 17C at each end of the journey.

Last Saturday during 18C weather we took the car on the first "long" journey it has had in quite a while, 80 miles round trip.

Battery temperature when we left home was 15.5C and after 40 miles on the motorway was still only 19 degrees, so barely above ambient.

On the return we stopped for 15 minutes for a rapid charge, this pushed it up from 20 to 22C, then the rest of the way driving home it peaked at about 27C.

So not very high at all! During the rapid charge the AC didn't even come on, only the fan, as the battery was too cold for optimal rapid charging speeds.
 
PV1 said:
In all seriousness, though. DBMandrake, per your signature, your car is a 2011. When most of us here in the States bought our cars, there was an addition to the owners manual after it was printed in the form of an orange paper, stating that a change in the car's software made it so that a balance charge was activated when charging was initiated at 2 bars charge or less. Do earlier versions of the car (2009-2011) have this feature?
Yes, mine seems to have this, perhaps added as a software update.

If the car is at 2 bars or less when you start charging it sometimes after about 10 minutes charging "pauses" for up to 30 minutes where the car and charge point says the car is still charging but the power drawn drops from 3.3kW right down to about 30 watts. I can only assume balancing is occuring, I have not tried putting my diagnostic tool on to confirm this but I think it's a fair bet.
 
An interesting thing happened yesterday, the Ah capacity rating reported by Canion went up! :shock: From 36.1Ah to 37.1Ah...

I've added this to an updated graph below:

uc


Some explanation of the newly added figures. The reading of 37.6Ah was the first reading where I noticed an out of character drop in the Ah figure, the following day I ran the full Diagbox battery calibration procedure which caused the reading to drop even further to 36.1Ah, since then it has stayed the same for about 10 days and now it has made a partial recovery and jumped back up to 37.1Ah, all by itself.

Hopefully it levels out here for a while and doesn't continue to decline at the rate shown since 38k.

The only thing I can think of is warmer weather has caused it to re-evaluate it's usable capacity, however it hasn't been THAT much warmer, and a smart BMS system should already have correction factors to account for loss of usable capacity in cold weather when estimating the "true" warm weather usable capacity.
 
DBMandrake, good news that your apparent capacity went up! Others have experienced a similar phenomenon, which is yet another reason not to get too obsessed with the i-MiEV's capacity readouts.

Your linked graphic doesn't seem to work, at least for me using a Mac and Safari browser. Extracting the link and using it as a URL gets a big long Google error message.

Without rigging up some sort of a datalogger, I don't know if I have the patience to watch CaniOn and wait for the "timeout" to occur and then determine if some type of balancing is actually taking place. Hope you do. :geek: :)
 
Strange.

The image is hosted on google drive - same as all my other images. I just checked on a browser that was not logged into my google account and I was able to view the image. I also tried it in both Chrome and IE.

So not sure why you can't see the image! Can anyone else see it ? Unfortunately this forum doesn't let me upload images so there's not much else I can do.
 
DBMandrake said:
The image is hosted on google drive - same as all my other images. I just checked on a browser that was not logged into my google account and I was able to view the image. I also tried it in both Chrome and IE.
So not sure why you can't see the image! Can anyone else see it ? Unfortunately this forum doesn't let me upload images so there's not much else I can do.
I tried logging in using Chrome where I'm automatically logged into Google and it worked great! Sorry for the disruption.
 
Time for an update on the dying cells situation.

Capacity has continued to drop at an alarming rate and it does indeed seem that cells 25 and 70 are slowly but surely dying, with cell 69 also showing signs of being halfway as bad as 25 and 70, with the other 85 cells still looking relatively normal. First the Ah degradation over time:

uc


The blue dots and line are actual Ah readings taken from the car using either Diagbox or Canion. From 28k miles to 38k miles the degradation rate was linear and approximately 0.1Ah per 1000 miles, after which a series of three large drops has occurred, which I believe are a result of cells 25 and 70 losing capacity much more rapidly than all the others, limiting the effective usable capacity of the pack.

The red line is a linear extrapolation of where I think the Ah capacity would have been if cells 25 and 70 weren't prematurely dying, in other words it should still be at about 38.2Ah instead of the 35.6Ah it is now.

As can be seen from the straight red line, the degradation from 28k to 38k was completely linear before the sudden drops occured. The gradual linear decline will be the programmed in "cell degradation model" the BMS uses in between actual measurements, with the "sudden" drops representing occasions where the BMS has measured the capacity and found it to be well below the predicted level, forcing it to update it's Ah estimate.

Now let's look at the degree of cell imbalance after discharging. For a given Ah capacity mismatch between bad and good cells, the voltage will start off balanced between all cells at 100% and start to diverge at some point below about 50%. The closer you get to 0% SoC the more extreme the voltage difference will become so to get consistent results it should ideally be checked at the same SoC or some extrapolation should be applied.

Here is the voltage imbalance at a 10% SoC from one of my images earlier in this thread posted back in April:

uc


Even as low as 10% SoC the peak difference is 50mV, which is certainly higher than it should be, and it's clear that cells 25 and 70 are weak, but at that point they are not really bad yet. Has it got worse since then ? Unfortunately yes! Here is a reading taken yesterday at 16.5% SoC:

uc


If the condition of the cells was the same as April, you would expect the voltage difference to be less than 50mV because this was taken at a higher SoC of 16.5%. But instead it is much worse - 80mV. So without a doubt the imbalance between cells 25 and 70 and the rest of the cells has got considerably worse since April, meaning that those two cells have continued to degrade at an accelerated rate relative to the rest of the pack. :( It's also apparent that cell 69 is becoming weak, although not as bad as the other two.

Now a snapshot taken during a rapid charge by which time the charge rate has dropped to 20kW. Rapid charging is also a good test of weak cells, because cells with either reduced capacity or higher internal resistance will show a higher voltage during the rapid charge than other cells. Again you can clearly see cells 25 and 70 poking out well above the rest, and cell 69 also poking out significantly:

uc


I don't rapid charge very often but something I've noticed now is that rapid charging speeds start tapering very early now. Even when I plugged in at 30% SoC during this test with a battery temperature of 25C (eg not cold) it only charged at 43kW for less than a minute before it started throttling back, with it down to 30kW by about 40% and 20kW by 60%. In other words throttling back a lot earlier and more than it used to.

I believe this is caused by the BMS limiting the charge rate to keep all cells below 4.105 volts, and if you have cells 25 and 70 peaking up to that voltage too soon due to being weak, the charge rate must be throttled back to avoid subjecting them to over voltage. So my rapid charging rates are significantly knobbled over what they were last year. :(

In short I think I'm in serious trouble here with the high mileage I do. I estimate that I've lost about 7 miles of summer range since the start of this year when the Ah capacity first started to drop suddenly.

More investigation into Peugeot's 8 year 60k mile battery warranty is giving conflicting results. I was originally told that older cars were retroactively increased to the new 8 years, but Peugeot have told other speakev members that have enquired that it only applies to cars sold after 2015 not older cars.

More importantly though there is no guarantee of minimum battery capacity like there is with many other EV's. So unless I have an outright cell failure that stops the car driving it would not be covered anyway, so the warranty is basically worthless.

So I've made the decision that I may have to do a cell swap of cells 25, 69 and 70 myself and am currently in the process of sourcing some cells and trying to talk my other half into the idea that I actually need to buy them even though the car is still currently driving! :lol:

I still have just over 2 years on a personal loan to pay the car off so a replacement pack out of warranty is not an option, and a cell failure putting the car off the road permanently would be a disaster. The good news is that I think I have found a good source of low mileage second hand cells so even though I don't plan to do the swap until next spring if I can last until then (it's getting too far into winter to voluntarily do major car repairs) if I do go ahead with buying some cells I'll get them now and store them at the correct voltage until I need them.

I'm planning to get four cells, swap 25, 69 and 70, and keep one "new" one as a spare for the future.
 
Does the car charge to "Full", i.e. 16 bars on the fuel gauge? Failure to reach full is one criteria for pack replacement under warranty.

What does the canion graph look like when the pack is fully charged using your home EVSE? How much is the peak difference in cell voltage?
 
kiev said:
Does the car charge to "Full", i.e. 16 bars on the fuel gauge? Failure to reach full is one criteria for pack replacement under warranty.
Yes it does charge to 16 bars, however I've noticed on Canion that sometimes it stops at 98% instead of 100% on a Level 2 charge.

What degree of battery malfunction causes it to indicate less than 16 bars after fully charging ? A usable Ah capacity below a certain threshold ?

You say it is one of the criteria - is this for Citroen/Peugeot in the EU/UK, or for Mitsubishi in the US/EU/UK ? I don't suppose you happen to know all the official criteria that warranty battery pack replacements are based on ? I have even contacted Peugeot UK head office but cannot get any useful information out of them.

I suspect it's not "bad" enough yet to meet any criteria they may have, however the car turns 8 years old next June and I do 12k miles a year in it.
What does the canion graph look like when the pack is fully charged using your home EVSE? How much is the peak difference in cell voltage?
I'd have to check but as far as I know the cell voltage is balanced within 10mV after a full Level 2 charge. It's only after the battery has discharged below about 40% that the voltage of the weak cells starts to drop a lot faster than other cells, suggesting the weak cells have less usable capacity than the rest.

One other thing I forgot to mention is that rapid charging last summer always used to stop at exactly 82% reported by Canion or the Rapid charger. This summer, since the cell problems have appeared, rapid charges often stop anywhere between 74% and 80%, even though the car may have been charging for less than 20 minutes. I don't think stopping before 82% is normal rapid charging behaviour except in extreme cold where it takes long enough to hit the 30 minute rapid charge time limit.
 
Not that it's worth bragging rights, but I think my battery's sicker than yours. I'm no longer confident to do my longest regular cold season trip, at 54.4 mixed driving miles without a DCFC session. Most recent low SOC capture was a month ago, when resting at 6% SOC, Cell#8 was 3.72V while Cell#18 was way down at 2.90V. That's a pretty big spread! Pack voltage was 304.8.

Previous capture a month prior was again Cell #8 as the highest at 3.70V and #19 down at 3.07V, at 4% SOC, pack voltage 306.5. Pack capacity down to 33.2 Ah

Time to fire up the MUT3 again.
 
jray3 said:
Not that it's worth bragging rights, but I think my battery's sicker than yours. Most recent low SOC capture was a month ago, when resting but not charging at 6% SOC, Cell#8 was 3.72V while Cell#18 was way down at 2.90V. That's a pretty big spread! Pack voltage was 304.8.

Previous capture a month prior was again Cell #8 as the highest at 3.70V and #19 down at 3.07V, at 4% SOC, pack voltage 306.5. Pack capacity down to 33.2 Ah

Time to fire up the MUT3 again.
Do you have Canion to capture a visual representation of all the cell voltages at a low SoC to see what kind of cell to cell variations you see ? Are the cells still balanced at full charge ?

What usable Ah capacity does the car report ? I'm guessing a lot lower than my 35.6Ah.... and what sort of range are you still getting ? Any odd behaviour from the car such as charging difficulties ?
 
I don't have a currently functional CanIon setup. That experience with Android devices convinced me to stick with the iPhone.... :geek:
Pack capacity is 33.2 Ah and falling. I'll give CanIon another try for the pretty graphs, but scrolling through with the MUT3 previously showed a well balanced pack just off charge. (Overnight L2)

I saw 62 or better RR all summer, but these frosty mornings are now more like 45 RR after a preheat, but HVAC turned off, IIRC...

No odd charging behavior since my charger replacement this summer, and a DCFC still takes closer to 20 minutes than 30.
 
DBMandrake said:
What degree of battery malfunction causes it to indicate less than 16 bars after fully charging ? A usable Ah capacity below a certain threshold ?
To not show 16 bars after a full charge, pack charge level would need to be 92% or less, as this is when the top bar disappears when driving.

Since all the cells are pretty much balanced at full, that's why the car still shows 16 bars after charging. For some other reported cell failures (such as mine a few years ago), something failed with either the cell or the BMS that caused the cell to discharge. Your cells look like they are simply degrading faster than the others and aren't being individually discharged. Unfortunately, I don't believe this would qualify for warranty replacement under US market warranties. We had to sign waivers stating that capacity loss wasn't covered. However, a loophole to this would be that eventually the degradation would cause the car to not charge to 16 bars, at which point it would qualify. The car will terminate charging if the minimum charge rate causes any cells to go over 4.11 volts.

I would definitely find out about warranty work first. If that's a no-go, then cell replacement is the next step.
 
PV1 said:
DBMandrake said:
What degree of battery malfunction causes it to indicate less than 16 bars after fully charging ? A usable Ah capacity below a certain threshold ?
To not show 16 bars after a full charge, pack charge level would need to be 92% or less, as this is when the top bar disappears when driving.
Yes I understand that, I was just wondering what scenario would cause the car not to charge to 100%.
Since all the cells are pretty much balanced at full, that's why the car still shows 16 bars after charging. For some other reported cell failures (such as mine a few years ago), something failed with either the cell or the BMS that caused the cell to discharge. Your cells look like they are simply degrading faster than the others and aren't being individually discharged.
Yes, my cells are not self discharging and they are balancing correctly at 100% charge. The bad cells simply appear to have lower Ah capacity and possibly higher internal resistance (based on the voltage rising above the others during a rapid charge) than the good cells, and furthermore their Ah capacity is dropping at a much faster rate than the other cells (at least 3x faster per 1000 miles) and that is the real concern - not that they have less capacity than the others, but that the discrepancy between the bad and good cells is widening at an alarming rate. (It has got a lot worse just between April and October as can be seen by the low SoC voltage balance from April and October)
Unfortunately, I don't believe this would qualify for warranty replacement under US market warranties. We had to sign waivers stating that capacity loss wasn't covered. However, a loophole to this would be that eventually the degradation would cause the car to not charge to 16 bars, at which point it would qualify. The car will terminate charging if the minimum charge rate causes any cells to go over 4.11 volts.
Ah.... I presume this applies to rapid charging as well ? That would explain the premature rapid charging throttling and cutting off before 82%. The bad cells rapidly rise to 4.105 volts (high internal resistance ?) and stay there during most of the rapid charge session, this forces the BMS to throttle the charge rate earlier while the other cells are still at a significantly lower voltage.

From what you're saying it sounds like once the charge rate drops below a certain threshold if the voltage still tries to go over 4.11 volts it aborts the charge early. I can certainly see how that could happen in a rapid charge since the charge rate is high enough to push a weak cell high in voltage, and the balancers are not used during a rapid charge. (and wouldn't be effective anyway) It seems like the cells would have to have a pretty serious fault for this to occur with a Level 2 charge though.

It may also be that rapid charges regularly aborting significantly below 82% and before 30 minutes in warm weather is an early warning sign that there are one or more weak cells.. It didn't happen to me at all last summer (always stopped at 82% on the dot) while this summer I was lucky if it ever got past 80% without stopping, it was always randomly stopping anywhere from 72% to 80% and the charge rate was very obviously slower than last year.
I would definitely find out about warranty work first. If that's a no-go, then cell replacement is the next step.
I'm confident the degree of degradation the pack has at the moment won't be covered under warranty (as there is no degradation guarantee) and that it's extremely unlikely there will be an outright failure in the remaining months of the warranty. So I think I'm on my own doing a 3 cell replacement.

On the upside, if I do the replacement and the problem is as I've diagnosed, I should gain back about 7 miles of precious range, arrest the rapid decent in battery Ah capacity I'm seeing now, and restore full rapid charging performance. All worthy objectives, even if the car is still driveable at the moment.

Finding somewhere with a two post lift that I can work at is the major stumbling block.
 
DBMandrake said:
...
Yes I understand that, I was just wondering what scenario would cause the car not to charge to 100%.

In my case i had a lagging cell. It somehow discharged below the level of the others and would never come back up. So it was the first to hit the bottom and limited the driving range, and it never made it up, so charging stopped when all the other cells were full (~4.1). The fuel gauge is reading the average pack voltage and the laggard cell brought the average down, so it was showing less than 16 bars.

i suspect the cell may have been okay since it didn't act like as weak or failed cells as in your case (the quick rise to the top voltage during charging)--my guess was that something on the CMU board failed and was always discharging that cell. Over time the voltage difference kept getting larger until a "full" charge was showing less than 8 bars.

If it weren't under warranty i would have taken the pack apart to find the culprit and repair it, but i resisted the temptation and let them trash a whole bunch of good cells and i got a new pack under warranty. But on the other hand here is a link to where Martin's car was acting the same way and he replaced a cell and restored his pack, so it's hard to know what is the culprit.

i think you do have some truly bad or weak cells, but they are manifesting as reduced range or capacity degradation, and not the "lack of reaching full" on the fuel gauge. But it seems that those 2 cells would be getting over-charged if they were held high while waiting for the others to catch up?
 
DBMandrake said:
Time for an update on the dying cells situation.



So I've made the decision that I may have to do a cell swap of cells 25, 69 and 70 myself and am currently in the process of sourcing some cells and trying to talk my other half into the idea that I actually need to buy them even though the car is still currently driving! :lol:


I'm planning to get four cells, swap 25, 69 and 70, and keep one "new" one as a spare for the future.

Any luck on the sourcing of cells? I have an ion the same age as yours. Mine only has 35k on the clock and I haven't yet read any values from canion but eventually a few cells will need replacing.
I have seen a few crashed ions on copart for cheap but as I'm not an autobreaker, that would leave me with all the extra "car". Might be worth a few of us clubbing together to get an entire pack.

I did see some on ebay a while back but they were located in Canada and the seller wasn't able to send them.
 
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