Turtle at Half Charge Under Load?!?!?!

Howdy Ziad and welcome to the forum,

Yes that is a large voltage difference, it should normally be much less for example 40mV, i.e. 0.040 V. There is a low cell that is causing the turtle under acceleration.

A cell swap is possible, see this thread: http://myimiev.com/forum/viewtopic.php?p=23601#p23605

0.6 volt difference at 50% SoC is huge, and will definitely trigger the turtle mode.

Either you have a faulty cell, or a faulty LTC voltage monitoring chip on one of the CMU boards in the battery pack that is causing an intermittent faulty voltage reading for a cell. Both issues have been documented and diagnosed both on here and over in a couple of threads on speakev.com.

It will take some careful diagnosis to reliably confirm which you have, if you are prepared to go to the trouble and have good DIY skills. Both are repairable however they are both big jobs as it means dropping the battery pack out of the car and (carefully) disassembling it.

I have done cell swaps on my own car and also assisted another owner with diagnosing a faulty LTC chip so I know what's involved, and they're not jobs to be taken on lightly unless you're reasonably well equipped and determined and understand safety procedures for working on high voltage equipment. (The battery pack can give you a lethal shock if not treated with respect, even with the safety link plug removed) Access to a 2 post lift would help immensely - I did mine without a lift by standing the car up high on stands and lowering the battery down on threaded rods and it worked but it was a very time consuming and intricate job compared to using a proper lift.

Ended up replacing the 12 volt battery at the dealer and the dc-to-dc converter code never came back. After gaining some rapport with the dealer I've scheduled a test and talked to the technician. The dealership is fairly confident a replacement battery is in order. I'm still under warranty, so should be some what less painful. I am excited about getting a few more years out of the car. The dealership has a hill right next door, so it should be very easy to reproduce if they can't determine it with a scan. I ended up buying a scan tool and the cells that are lower are 10 and 11. About .4v to .6v at 50% load range has definitely took a hit also.

Graveaxis said:

I ended up buying a scan tool and the cells that are lower are 10 and 11. About .4v to .6v at 50% load range has definitely took a hit also.

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So two cells are 400-600mV lower than the rest ? At 50% SoC ? That's massive - I'm surprised the car would drive at all. :shock:

Careful diagnosis would be necessary to confirm whether it's two faulty cells (a little bit suspicious that they're side by side) or whether its a faulty LTC chip on a CMU board (since the same LTC chip will be monitoring cells 9-15) but if they are just going to swap the entire traction battery under warranty then that will of course swap all the cells and all the CMU monitoring boards which are bolted directly to the top of the cells, so will definitely fix the problem regardless of whether it's cells or LTC chip.

For a DIY out of warranty repair you'd want to figure out whether it was cells or chip of course.

What does it report for the Ah capacity on the first trip screen in Canion ?

So they did the quote un quote judgement test and they say the battery is a okay. They had the car 3 weeks and decided that they aren't going to replace the battery. They said that this is normal and techline was no help. I called corporate and they told me to pound sand. They said the only way they're going to replace the battery is if it doesn't charge up to full. They refused to give me any specifications for what normal and unnormal the gracian is....

Disturbing news about Mitsubishi's responses, not boding well for the future. Corporate change?

Graveaxis, do you have some screenshots or photos of your most extreme cell voltage disparity readouts? Interested in knowing what those voltages are at what overall SoC? Does your tool provide a battery capacity readout (e.g., in Ah)?

Could you refresh my memory: does Turtle kick in while driving down the highway and attempting to accelerate? How does the car react?

I'm also curious what your typical RR reading is when the fuel gauge is at 8 bars? In my case, when driving 'normally', it's somewhere around 32 miles for a battery having around 38Ah capacity.

I presume the fuel gauge is showing 16 bars when fully charged?

Finally, about how many miles can you presently drive from full before you get down to two bars while driving somewhat conservatively?

Just gathering some more information to see if we can help you somehow...

Oh, and it always helps to know where everyone is located -

http://myimiev.com/forum/viewtopic.php?f=13&t=3196

Battery is charging up to 16 bars. Battery capacities 27.5 amp hours. Probably drive about 26 miles maybe a little further. I don't really pay attention to the RR gauge. Pretty much the turtle light comes on any time vehicle is under load on any grade. Pretty disappointed in Mitsubishi corporate. Apparently I still have battery warranty till 2023.

https://photos.app.goo.gl/YgN7TBk1QzcLdvyz9

Graveaxis, thanks for the screenshot and information and updating your location. Looks to me like there is one seriously-weakened cell (#11) and a few other ones that aren't happy, and that's at 32%SoC.

Question: while driving down the highway and flooring the accelerator and the Turtle shows up, is there an accompanying decrease in vehicle speed? How about vehicle response at a lower SoC?

Can't help but wonder at what point the cell degradation becomes bad enough s.t. the charge won't go up to 16 bars. When my battery failed, one cell was seriously hurting and getting worse and the number of max bars was dropping with each charge.

As an aside, a year ago when Hyundai was offering a lifetime warranty on their Kona EV battery and I pressed them to understand what that meant, exactly, no one would give me an answer - not even the factory 'expert' reps at the car shows. They've subsequently rescinded that warranty... :evil:

Hi, I just bought a used peugeot ion with 105000 km from 2011 . i am a electric car neewbie, so please excuse the maybe stupid questions.. i got the same issue with my car: turtle appears when i accelerate fast or going up a steep hill. when it was around zero degrees outside it got worst and the car even slowed down to 5 kmh when the turtle appeared. battery was showing at least one third of capacity, sometimes more than half. i live in switzerland. are here maybe any members from switzerland that could help me find out if this is because of an bad cell ? could someone from switzerland borrow me this "obd link" so i could do a test with the canion app ? i would be very happy if someone could help me figure this out !

I have the same issue (turtle light comes on under load) with our 2012 SE. The car has about 36k miles and has been absolutely trouble free for the seven years that we have owned it. Until now, that is.

The dealer read the trouble codes and there were several : B1477, B1476, B210D and P1A2F. Since the first three of those codes appear to relate to the 12v battery, I will replace that tomorrow even though it tests good. If that resolves the issue, wonderful. If not, I am guessing that the P1A2F code indicates one or more bad cells.

I have already tried the battery rebalance procedure (i.e. drain it almost to zero, wait two hours, recharge with slow charger).

Am I missing anything with this?

Gearhead1961 said:

I have the same issue (turtle light comes on under load) with our 2012 SE. The car has about 36k miles and has been absolutely trouble free for the seven years that we have owned it. Until now, that is.

The dealer read the trouble codes and there were several : B1477, B1476, B210D and P1A2F. Since the first three of those codes appear to relate to the 12v battery, I will replace that tomorrow even though it tests good. If that resolves the issue, wonderful. If not, I am guessing that the P1A2F code indicates one or more bad cells.

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P1A2F is a "secondary" code which is set by other codes:

http://mmc-manuals.ru/manuals/i-miev/online/Service_Manual/2013/54/html/M154921160003100ENG.HTM

However none of the codes which can cause P1A2F (shown in that article) are listed above, so I must conclude that whatever diagnostic tool the dealer used did not read all the codes or the codes were reset before reading, so some information you need is missing.

I have already tried the battery rebalance procedure (i.e. drain it almost to zero, wait two hours, recharge with slow charger).

Am I missing anything with this?

Click to expand...

It's hard to know for sure when one of the codes (which triggered P1A2F) is missing, but in general turtle light coming on under load at a high SoC means you have one or more faulty (high resistance) cells in the traction battery.

Your dealer should have been able to diagnose this, but apparently they have not. If you want to have a go at confirming this yourself you can use an android tablet with Canion and Hobdrive using a suitable bluetooth OBD-II adaptor.

Hobdrive works with most adaptors but Canion only works with a limited selection of adaptors. I used Canion with an OBDLink LX successfully for years and it also worked with Hobdrive. (I no longer have one of these cars - I have a Leaf now and use the same adaptor with the Leaf)

Canion can show a realtime graph of all the cell voltages - if you have someone drive the car for you you can watch the cell voltages in real time, watch for any particular cells that drop much lower than others during acceleration and you will find your culprit(s).

If any cell drops below exactly 3.0 volts during driving the turtle mode will instantly come on. Normal no-load voltage of a nearly discharged traction battery is around 3.6 volts per cell.

Hobdrive is a bit more tricky to use (see other threads here for help) but is able to do limited fault code reading and may be able to provide the missing fault codes.

Duplicate post.

DBMandrake -

I do appreciate the information. Replacement of the 12v battery has been delayed a day due to some other obligations but i have taken the opportunity to download Canion and order an OBDLink LX. I am a little out of my depth with all of this but I am sure that I can muddle through and eventually get to an accurate diagnosis.

The problem is, of course, that if all of this leads to confirmation of one or more bad cells, I am dead in the water as I do not have the facilities or skill set necessary to drop the battery assembly and swap out cells. I guess I'll cross that bridge when I get there.

Well, I replaced the 12 volt battery today and ---- as expected --- it had no effect on the turtle coming on under load. OBDLink will be here in a day or two so I will see what the Canion app can tell me then.

Looks like cell 85 is the culprit, drawing down to 2.790 volts under load.

Gearhead1961 said:

Looks like cell 85 is the culprit, drawing down to 2.790 volts under load.

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Commiserations, but at least you identified a bad cell. How do the others look under load?

There are a half dozen other cells that fall into that 3.2 - 3.1 range under load but #85 really stands out as the bad guy.

Gearhead1961 said:

There are a half dozen other cells that fall into that 3.2 - 3.1 range under load but #85 really stands out as the bad guy.

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Sorry to hear about your troubles, it really looks like these early LEV50 cells degrade a lot faster in high ambient temperatures as the car has only done moderate mileage overall.

Even if you had the means to replace the bad cell, improvements will most likely only be short lived, therefore the only permanent solution is to change the complete pack. If I remember correctly the 10 year battery warranty expired last month but even if still in place a claim was unlikely to be successful as it charged up fully…

You could pay for a replacement yourself but dealer prices are astronomical and therefore I’m afraid it’s time to look for a successor…

I replaced a cell last year that was lagging at rest after a full charge. That cell is a trooper, the strongest cell in my pack. And my pack now gets up to 16 bars when charged (vs 3 before).

Now a new problem unfortunately. All my cells are strong at rest after a charge however 13, 87, 38 now sag below 3V under mild load at 8 bars and below. They get as low as 2.8 which triggers the turtle, and will bounce back to 3.4 after a rest. The cell I replaced is still at 3.8 under this scenario. I had to crawl home today, with a push assist to get up the driveway.

Looks like 3 more have to come out. Car has 25k miles.

I hate electric cars!

And now something new. Car is dropping bars while parked overnight. Cells still level but down fractionally. It got unusually cold here, down to 60 vs the normal 75 to 80.