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Discussion Starter · #1 ·
Hi all,

after alittle advice.

My brother owns a 2014 leaf tekna, its only done 18000 miles, he has owned it for 5 years.
Over the last 8 months we have noticed 1 cell (cell49 / 50) loosing voltage.
As an example, this cell is at 4.04v when all other cells are at 100% (4.23v) and balancing.

As a result, its effective capacity is now approx 9kwh.
At the end of the battery capacity, when in very low battery warning, the disparity between the higest and lowest cell is over 500mv, and battery warning lights on the dash are alight.
I have the error codes from leafspy, i have cleared them to enable the car to run safely as it was in reduced power mode with the warning lights on, erased codes to enable us to safely get the car to the dealer for examination.

From what I understand the leaf battery has in effect 2 warranties.

A. in the event of 4 bars lost or 60000 miles, wear condition

B. in the event of a battery failure, a 8 year or 100,000 miles warranty.

Now, Id say, B is in effect here as there is a defective cell inside the sealed battery pack, therefore the battery is in failure mode, not wear.

Can anyone confirm that in the event of a failure the battery is indeed warranted to 8 years or 100k miles.

Thanks in advance,
Anthony.
 

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From what I understand the leaf battery has in effect 2 warranties.

A. in the event of 4 bars lost or 60000 miles, wear condition

B. in the event of a battery failure, a 8 year or 100,000 miles warranty.
It might be best to check the warranty status depending on the exact age of the car. My May 2014 24kWh Acenta came with a 60k mile or 5 year capacity warranty (for 4 bars as you say); IIRC the 30kWh battery version was the first that came with the 8 year/100k warranty, but I’m not sure if this was applied to 24kWh cars at the same time. Worst case would be that warranty is now expired.
 

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Nissan Leaf 24 Tekna '64 reg
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Unfortunately I think 24kWh Leaf only have 5 years 60k miles warranty. That is what's written on my Dec 2014 Tekna 24kWh service manual.
875000B9-89A5-496A-B33D-3FE7E73CA8E7.jpeg
 

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Agree with other posters your warranty has expired.
What error codes are you getting ?
 

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Discussion Starter · #5 ·
Hi, the error codes are due to the mV disparity in voltages of the cells, due to 1 pair (49 and 50) being faulty, well, cell 49 that is in the same can as 50.

We have tried a force manual rebalance by plugging in the car 3 to 4 times after its completed to sort of try to force balance, but the rogue cell hasnt changed, in fact its getting worse over time.
In July it was 62mv divergence
2 days ago it was 102mV

Error codes were

P3180 000B EV/HEV HV BATT SYSTEM EVB-249
P33E6 0048 HV BATTERY cell controller EVB-143.

We have also tried 5 rapid charges in very quick time.
That procedure did increase the ah capacity by 3ah and the SOH increased from 86 to 89%
But sadly the rogue cell stayed at over 100mV lower than the rest.

So, im thinking ive either got a BMS issue, where the cell is draining via fault in the BMS

Or

the cell just needs a manual rebalance. OK itll mean opening up the pack, but somethong needs to be done to it now.

We think its gone bad due to my brothers very low usage of less than 2000 miles per year, plus, he only charged to 80%, never getting the cells as a pack to balance.

gutted that the pack looks like its out of warranty, but, it is what it is. A great car otherwise.

Anthony.
 

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As a result, its effective capacity is now approx 9kwh.
Should that be 19 or do you genuinely mean 9?? Surely the SOH should be a lot lower in this case?
 

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Nissan Leaf 24 Tekna '64 reg
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Your car is a lot worse than in this video, but this video shows you the rough idea of how to resolve it:

You can get in touch with that garage to get a quote?
 

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Discussion Starter · #8 ·
Hi Edd,

Due to the bad cell being considerable at a lower state of charge than the rest, the energy counted n at the wall was 9kwh.
so, currently the car has a max range of about 30 miles max.
This is due to the fact that at the lower end of the charge, the bad cells is 500mV out of delta lower than the rest, this really low cell then triggers early low battery warning and very low battery warnings on the dash.

Thanks


Should that be 19 or do you genuinely mean 9?? Surely the SOH should be a lot lower in this case?
 

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Discussion Starter · #9 ·
hi buddy,

thats what we are intending doing. Cell 49/50 is the 1st cell bank off the main big bank at the back.

Ive stripped a few packs before, one i sold one on, the other we are using as an energy store, and I have 2 really good gen2 cells here as spares, so that looks our way out of this situation. I also have a friend that owns a car vehicle repair garage, so all in all we are quite fortunate.
however, we would obviously rather not be opening up the pack at just 18000 miles, but we are where we are.

Thanks.


Your car is a lot worse than in this video, but this video shows you the rough idea of how to resolve it:

You can get in touch with that garage to get a quote?
 

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Hi, the error codes are due to the mV disparity in voltages of the cells, due to 1 pair (49 and 50) being faulty, well, cell 49 that is in the same can as 50.

We have tried a force manual rebalance by plugging in the car 3 to 4 times after its completed to sort of try to force balance, but the rogue cell hasnt changed, in fact its getting worse over time.
In July it was 62mv divergence
2 days ago it was 102mV

Error codes were

P3180 000B EV/HEV HV BATT SYSTEM EVB-249
P33E6 0048 HV BATTERY cell controller EVB-143.

We have also tried 5 rapid charges in very quick time.
That procedure did increase the ah capacity by 3ah and the SOH increased from 86 to 89%
But sadly the rogue cell stayed at over 100mV lower than the rest.

So, im thinking ive either got a BMS issue, where the cell is draining via fault in the BMS

Or

the cell just needs a manual rebalance. OK itll mean opening up the pack, but somethong needs to be done to it now.

We think its gone bad due to my brothers very low usage of less than 2000 miles per year, plus, he only charged to 80%, never getting the cells as a pack to balance.

gutted that the pack looks like its out of warranty, but, it is what it is. A great car otherwise.

Anthony.
Hi Anthony
You are having exactly the same issue that I had last year
139256


Those are my error codes
139257


Thats my bad cells quite why it flagged up 47 I dont know.
My symptoms were after about 30 miles on a full battery the range just dropped off as seen below I charted the state of the battery over a circular route even reversing the route to ensure it wasnt due to terrain etc.
139258


Unlike you I was fortunate that my battery was still under warranty and after some gentle persuasion Nissan sent the car to Lookers, they replaced the 2 modules car was back within a week so a good turn around.
However they didnt precharge the replacement cells correctly there was a 43mV delta across the battery, when I questioned this I was told that it would balance out on its own, to this day and like you I have tried all sorts to make it balance it has failed to do so.
The battery is in good condition still have all 12 bars and it discharges at a much more linear rate the range has improved by a good 20 miles and on a 24kWh that is a lot.
 

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thats what we are intending doing. Cell 49/50 is the 1st cell bank off the main big bank at the back.

Ive stripped a few packs before, one i sold one on, the other we are using as an energy store, and I have 2 really good gen2 cells here as spares, so that looks our way out of this situation. I also have a friend that owns a car vehicle repair garage, so all in all we are quite fortunate.
however, we would obviously rather not be opening up the pack at just 18000 miles, but we are where we are.
Sorry to hear of your predicament.

Without seeing the Leafspy screenshot it does sound like you have a faulty cell, and if you have good replacement cells of the same generation and capacity at hand, and some experience stripping packs and somewhere to work I would say as long as you're confident working with high voltages and know what to do just bite the bullet and do a cell swap!

Although I've not done a Leaf pack before (and hope I never have to!) I have done a cell swap on the Peugeot Ion (4 cells in fact) and managed to do it by myself, on a driveway with an improvised method of lowering the battery pack down and a home built battery trolley. (Sure, it did take me about 3 days due to the less than ideal working conditions and working alone :) )

A couple of tips if you go ahead with doing it yourself though:

1) Make sure if at all possible that you swap the cell when the pack is fully charged and that the replacement cell is also fully charged on an external Lithium Ion charger before the swap. You want the voltage of the replacement cell to match the good cells within about +/- 10mV or so. The Leaf has a really slow balancing system and if there is a large error in the state of charge/voltage of the replacement cell vs the cells already in the pack it could easily take months for balance to be achieved. You're better to spend a small amount of time precisely matching the cell voltage with an external charger before the swap.

If you can't fully charge the pack due to a charging error then charge the replacement cell up to the same voltage as the average of the good cells and that should be close enough, as long as you're not at a really low SoC where differences in capacity of the new cell (such as the new cell being better than the majority of the pack) could cause an issue.

2) Not sure about the Leaf but on the Ion I had to use a (grey market copy of) the dealer diagnostic tool to force the BMS to do a full capacity calibration to become "aware" that the battery now has a lot more capacity than it had a day ago. BMS's don't generally like to accept that a battery suddenly got a lot better, they have to be told to do a recalibration before they will let you use the new found capacity. So you might want to see if you can borrow or get access to use the Nissan diagnostic tool after the swap to trigger a recalibration, and if possible read up on the process before starting on the job. I'm not sure if any other 3rd party tools can do this for you.

Other than that it seems like a fairly clear cut case of swapping a bad cell and getting the car back to full (for its age) health.
 

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Discussion Starter · #12 ·
Hi all an Layzee

Your error codes were identical to mine plus your fault.

what i can do is charge to car to max the garage is 2 miles away, ive done the journey and when i get to the garage the ave bat cell volt is 4.10v

I have 2 very good leaf cells as spares here already, do i`ll charge those in readiness with my hobby ISDT charger to 4.11v

Then do the swap out. Im hoping cell 49/50 which in effect is battery number 25 is the top battery of the rh side stack.
We are fortunate to have access to the garage equiment like 2 poster lift etc... and have experience with these batteries in manual balance charging, its just a shame e have to get inside the pack to do it.

Whe i phoned nissan uk they said the battery was in warranty, but perhaps they were thinking it was a 30kwh model, not the 24.

Hey ho, it is what it is.

I`m hoping to do the swap toward the end of the month.
Report back with what we encountered at that time.

I
 

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Hi all an Layzee

Your error codes were identical to mine plus your fault.

what i can do is charge to car to max the garage is 2 miles away, ive done the journey and when i get to the garage the ave bat cell volt is 4.10v

I have 2 very good leaf cells as spares here already, do i`ll charge those in readiness with my hobby ISDT charger to 4.11v

Then do the swap out. Im hoping cell 49/50 which in effect is battery number 25 is the top battery of the rh side stack.
We are fortunate to have access to the garage equiment like 2 poster lift etc... and have experience with these batteries in manual balance charging, its just a shame e have to get inside the pack to do it.

Whe i phoned nissan uk they said the battery was in warranty, but perhaps they were thinking it was a 30kwh model, not the 24.

Hey ho, it is what it is.

I`m hoping to do the swap toward the end of the month.
Report back with what we encountered at that time.

I
Dont know if you have this but it may be of some help with your battery swap it tells you how to calculate the replacement cell voltages, plus lots of other useful info
 

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