Battery Degradation

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fjpod said:
Since the weather has turned a little colder here in NY, I think my RR number after a full charge has decreased...but I am also driving the car a little harder out of necessity.

I don't think I will know if it is real battery degradation or just the other factors at play, until next spring/summer.


Its definitely interesting watching how the weather affects the range. Today on a typical 2-3 C day here in Niagara with little wind, I made it to Buffalo with two bars remaining. I think the wind has greater affect on range at this temperature than the temperature does. When the wind is strong and I can hear it howl around the windshield, I can usually count on a faster power drop.
 
Good afternoon, sorry for my english writing through a translator.
Who can tell what's going on with my battery,
I attach 4 pictures, the first 2 are completely discharged before the battery is disconnected.
The following pictures are fully charged.

car of the year 2011, 68000km,

on the counter enters 10 kilowatts, on one charge in the summer makes up to 60km.

say the battery is dying or something can be done.







 
Howdy Aleks,

Welcome to the forum.

It appears that cell #43 is weak and probably worn out.

Due to the operating system, the capacity and range of the battery pack is limited by the weakest cell.

We have seen a member (Martin) replace just the one weak cell and restore his pack, see a video in this thread:

http://myimiev.com/forum/viewtopic.php?p=23601#p23605
 
Thank you, I understand that this is the assembly of lev50 4s

tell me to change one or 4 pieces at once? 8 pieces?

Are these cells suitable for replacement?

https://item.taobao.com/item.htm?spm=a230r.1.14.28.576d3618Bhcyvn&id=547637580633&ns=1&abbucket=10#detail

kiev said:
Howdy Aleks,

Welcome to the forum.

It appears that cell #43 is weak and probably worn out.

Due to the operating system, the capacity and range of the battery pack is limited by the weakest cell.

We have seen a member (Martin) replace just the one weak cell and restore his pack, see a video in this thread:

http://myimiev.com/forum/viewtopic.php?p=23601#p23605
 
They appear to be the same sized cell, but it's not clear if these are new or used.

Also based upon the limited description information (for example: "Brand: AAA") it's not clear that these are actual G.S. Yuasa LEV50 (50 A-Hr) cells, or some copy, but they do look like real Yuasa LEV50 cells.

Be sure to ask them about these factors before you pay.


If they are the real cells and new, then it is a great price.

If they are real but used, then it is a good deal.

If they are fake, then it is a big risk.
 
But the fact that the cells do not fall to the required level of 2.8 V is also caused by a bad cell ??
and what can be done now?

It is believed that if you replace one new element, the device will stop charging, is it true?


kiev said:
Howdy Aleks,

Welcome to the forum.

It appears that cell #43 is weak and probably worn out.

Due to the operating system, the capacity and range of the battery pack is limited by the weakest cell.

We have seen a member (Martin) replace just the one weak cell and restore his pack, see a video in this thread:

http://myimiev.com/forum/viewtopic.php?p=23601#p23605
 
AleksM said:
But the fact that the cells do not fall to the required level of 2.8 V is also caused by a bad cell ??
and what can be done now?

It is believed that if you replace one new element, the device will stop charging, is it true?

The car will shut down when only 1 cell reaches the low voltage limit, and #43 will likely be the first cell to go down to the low level in your car. The rest of the cells will still be above the limit but will not be accessible. Either that bad cell, or the module of 4 cells, or the entire pack, must be replaced to restore full range of operation.

i have never heard that the device will stop charging if one cell is replaced.

In fact, in the video link of the thread i posted is shown the replacement of just one cell, and he was able to charge and drive the car as normal--no problem with charging. You can change the settings to watch it at slower speed if desired.
 
There is more than one weak cell shown in those fully discharged cell voltages - I count about 5 weak cells that are 200mV or more below the average voltage. It's difficult to tell looking at a table of numbers though.

If possible I would recommend using Canion to get a screenshot of the voltage graph when near discharged as it is much easier to evaluate in visual form. For example here is a fully discharged graph from my car a year ago:

uc


As can be seen, cells 25, 69 and 70 are weak on my car with 25 and 70 being the worst. They also have high internal resistance which shows as an excessively high voltage during rapid charging which limits peak charging rate prematurely.

The 25.8Ah reported on your car is a severely degraded battery. (new is about 46Ah) Mine has done 50k miles and is down to 35.2Ah which I already consider to be significantly lower than it should be for the mileage. (I also have some weak cells) However your low figure may be the result of just a few bad cells.

The problem with replacing them is that the replacements have to be at least as good as the good cells remaining in the pack, and there is no easy way to know what the Ah capacity of the best cells in your pack are.

Any second hand cells are likely to be degraded and may be even worse than the ones you're trying to replace. I found some second hand cells for my car but when the seller tested them they were down to about 28Ah so were considerably worse than even the weak ones in my pack! This despite them coming from a car with half the mileage as mine. (Needless to say the purchase was cancelled)

So beware of second hand cells unless the seller is an EV battery specialist and willing to measure their Ah capacity and vouch for them.

AleksM said:
But the fact that the cells do not fall to the required level of 2.8 V is also caused by a bad cell ??
and what can be done now?
Not sure what you mean by "required level of 2.8 volts" ?? These cars do not discharge the cells this low. Normal cutoff voltage at 0% SoC for an 88 cell car is 320 volts for the pack or about 3.64 volts per cell. If the pack is badly degraded the cutoff voltage may be lower than 320 volts however.
 
canion expensive

I plan to buy new cells and change them in whole modules of 8-16 pieces, approximately 8-16 pieces per month

figures translated into the schedule

 
Replaced 4 cells.
https://www.drive2.ru/l/531427780760437096/

working scanner with great functionality
https://www.drive2.ru/l/530716671615172946/

kiev said:
They appear to be the same sized cell, but it's not clear if these are new or used.

Also based upon the limited description information (for example: "Brand: AAA") it's not clear that these are actual G.S. Yuasa LEV50 (50 A-Hr) cells, or some copy, but they do look like real Yuasa LEV50 cells.

Be sure to ask them about these factors before you pay.


If they are the real cells and new, then it is a great price.

If they are real but used, then it is a good deal.

If they are fake, then it is a big risk.
 
I have a 2012 MiEV, bought in summer 2013, with about 88,000mi and get a summer range of about 40mi driving country roads and in a small town. The range dropped abruptly after about 40,000mi and I started to have a dead 12V battery, if I didn't use it for a couple of days. Over the years I have swapped a couple of these under warranty. Do these 2 things go together and are these related to the "potential low durability..." letter from Mitsubishi. I love this little and simple car, but the battery degradation(low charging?) is detrimental to its use. EvBatMon shows 25Ah and 52PMC. I will be with Mitsubishi on Monday.
 
Carsten said:
I have a 2012 MiEV, bought in summer 2013, with about 88,000mi and get a summer range of about 40mi driving country roads and in a small town. The range dropped abruptly after about 40,000mi and I started to have a dead 12V battery, if I didn't use it for a couple of days. Over the years I have swapped a couple of these under warranty. Do these 2 things go together and are these related to the "potential low durability..." letter from Mitsubishi. I love this little and simple car, but the battery degradation(low charging?) is detrimental to its use. EvBatMon shows 25Ah and 52PMC. I will be with Mitsubishi on Monday.
Carsten, I moved your post into this forum because the one you originally posted in is a poll of the OBC/DC-DC.

When you say "Over the years I have swapped a couple of these under warranty." are you talking about the 12v or main battery pack? To be clear, how many times have you replaced each of those batteries?

Surprising that you noticed rapid degradation after 40,000 miles. What is your usual charging regimen and how was your car treated in winter?
 
Carsten said:
I have a 2012 MiEV, bought in summer 2013, with about 88,000mi and get a summer range of about 40mi driving country roads and in a small town. The range dropped abruptly after about 40,000mi and I started to have a dead 12V battery, if I didn't use it for a couple of days. Over the years I have swapped a couple of these under warranty. Do these 2 things go together and are these related to the "potential low durability..." letter from Mitsubishi. I love this little and simple car, but the battery degradation(low charging?) is detrimental to its use. EvBatMon shows 25Ah and 52PMC. I will be with Mitsubishi on Monday.
Do failing 12v batteries and failing traction batteries (low range) go together ? My answer would almost certainly be no.

Correlation (both starting to give trouble at about the same age) does not equal causation. Lead acid batteries only last a certain number of years before they need replacing and a 2012 car is now at an age where the 12v battery is well past due. However there is nothing that a failing 12v battery can do to cause cells in the traction battery to fail, or affect the range.

I replaced the 12v battery in my 2011 Ion this year (8 years old) and it was absolutely stuffed. The Ah capacity should be about 34Ah and it was measured at only 1Ah when I tested it outside the car. Yet the car was still running. Because there is no starter motor and the load is provided by the DC-DC charger when the car is in READY or is charging, the 12v battery doesn't have much to do except "start" the car power powering the ECU's and high voltage contactors, and provide a ballast once running, so it can get very VERY bad before symptoms are noticed, unlike in an ICE where it will fail to turn over the starter and be replaced long before it got that bad.

However as for the range dropping abruptly after 40k miles I'm afraid you're not alone. I have this problem now too. I bought my 2011 car in 2017 with 28k miles on the clock - at the time the traction battery was at 39.9Ah (good for its age compared to other cars) and summer range was around 65 miles, winter range around 43 miles. It's now at 56k miles and battery Ah capacity is down to 32.6Ah, summer range is about 54 miles, winter range about 35 miles, a massive loss to the point that I can't make my commute in winter without a rapid charge on the way home.

I have been keeping a record of the degradation and it started to accelerate dramatically around 40k miles, and I'm not the only one to experience this - I'm aware of a couple of other cars that have behaved the same.

Before 40k miles the degradation rate was about 0.1Ah / 1000 miles. It is now at about 0.4Ah / 1000 miles so dropping very rapidly and at this rate the car will be unusable to me within a year. In my case I believe that 3 cells have gone "bad" around 40k miles. For a full deep dive into the problems with my battery pack check our my "Is my battery dying" thread. You can read it from the beginning if you like however you may be better to jump to this post near the end first which has the conclusions after 2 years monitoring:

http://myimiev.com/forum/viewtopic.php?f=23&t=4014&start=50#p39013

There is a very obvious knee in the degradation rate graph around 40k miles.

To see whether your car has the same issue, if you have an Android device, you need to get yourself the free Android app Canion, and an OBDLink LX bluetooth adaptor to connect it to the car.

Using that app you can check the Ah capacity of the traction battery which will give you an overall measurement of the health of the battery - my guess is yours is in the very low 30Ah's by now (worse than mine) or even high 20's. For reference a new battery is 45.8Ah. It's possible to see whether this is overall degradation of all cells in the pack or just a few bad ones.

To do this you would charge the car up to 100% and let it finish balancing, then drive the car until the battery SoC as reported by Canion is down to about 20%, then switch to the voltage graph page and see if there are any outlier cells as in the graphs posted in my thread above - individual cells that are at a much lower voltage than the majority of cells at a low SoC are weak cells with a lower Ah capacity than the rest. The overall usable capacity of the pack is always limited to that of the weakest cell so it only takes one bad cell to kill your range.

I am going to do a cell swap of the faulty cells in the next few weeks so I may have a happy outcome for my car - I'm not expecting it to go back up to 39.9Ah, but even if it goes up to around 37Ah and the degradation rate drops back to 0.1Ah / 1000 miles that will be a win over what I have now.

Keep an eye on my thread over the coming weeks where I will post the results.
 
Simon,
It's the 12V-batteries that die all the time. If I don't use the car for a couple of days, it doesn't open with the key fob and doesn't start. initially I suspected the aftermarket front and back traffic camera, but even with them off, it happens. With the car of and no charger connected I have a draw of 1.91A with the cameras and 1.74A without the cameras. It has always been like this. What is drawing the current?
I have the canion and the EVbatMon-apps and the OBDLink BT-reader. None of the apps have ever worked other than sporadically. The OBD-reader works wonderful on my ICE-cars.
The Apps complain now about not being for new Android. Do I have to revive my old S4?
Regards,
 
Carsten said:
...
I have a draw of 1.91A with the cameras and 1.74A without the cameras. It has always been like this. What is drawing the current?

That's a huge current draw when the car is OFF, no wonder you are draining the aux battery. It's like you have a stuck relay or something. Have you installed any other aftermarket items to the 12-Volt system?

If you can monitor the current with a meter, then remove fuses one-at-a-time to see which circuit has the draw.
 
Kenny,
I will be at the local Mitsu-dealer to get myself and the EV introduced to them - I just moved to VT at the End of August. They will (hopefully) check the drain and the main battery and let me know, if the recall notice applies to me. Should be interesting. They can't be worse than the dealers in MD (Gaithersburg & Frederick).
 
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