Range of two LEAFs very different in same 30 mile route

[avp]

Could be the problem.

Definitely could be the problem - 3.976 V average is around 70% charged, but 3.903 V is around 50% charged.

Hi. How can you make the relation between the potencial value (in mV) and the battery capacity? Is there a formula or something like that?
Thank you very much!!

[RegGuheert]

Could be the problem.

Definitely could be the problem - 3.976 V average is around 70% charged, but 3.903 V is around 50% charged.

Hi. How can you make the relation between the potencial value (in mV) and the battery capacity? Is there a formula or something like that?
Thank you very much!!

A bunch of us have collected quite a bit of data from our LEAFs using LeafSpy. I can confirm that 3.903V is right around 50% SOC for my LEAF. That single cell will dictate how much capacity the entire car has. There are 96 cells stacked in series in the LEAF, but those cells are actually PAIRS of cells in parallel. I suspect that one of the two cells in that pair may have failed (open) and is not contributing to the overall capacity of the car.

I recommend that you run the car down to LBW and provide a screenshot of LeafSpy. It would be best if you get that picture JUST after the low cell drops below 3.712V. Then we can calculate whether or not Nissan believes that is a failed cell-pair. (This test is known as the Cell Voltage Loss Inspection (CVLI).)

While the dealership can replace the module which contains the (likely) bad cell, personally I would not want the dealer opening the sealed battery in my new LEAF. Better to have a fresh one from the factory, IMO.

[avp]

A bunch of us have collected quite a bit of data from our LEAFs using LeafSpy. I can confirm that 3.903V is right around 50% SOC for my LEAF. That single cell will dictate how much capacity the entire car has. There are 96 cells stacked in series in the LEAF, but those cells are actually PAIRS of cells in parallel. I suspect that one of the two cells in that pair may have failed (open) and is not contributing to the overall capacity of the car.

I recommend that you run the car down to LBW and provide a screenshot of LeafSpy. It would be best if you get that picture JUST after the low cell drops below 3.712V. Then we can calculate whether or not Nissan believes that is a failed cell-pair. (This test is known as the Cell Voltage Loss Inspection (CVLI).)

While the dealership can replace the module which contains the (likely) bad cell, personally I would not want the dealer opening the sealed battery in my new LEAF. Better to have a fresh one from the factory, IMO.

Ok. Thanks a lot!!! Tomorrow I,ll do it. First in LBW and then when it reaches 3.712 mV.
Is this CVLI something official in Nissan? Today the dealer technician told me that this cell was low but not low enogh to be considered a bad cell. They have no idea about EVs. He showed me that GOM indicated 132 km (82,5 miles), as an evidence of battery health!!!
Today, after starting at 100% and driving 57,7 km (36 miles) the battery was at 6%. I continued to turtle. 77,8 km (48,6 m) Average speed: 100 km/h (62,5 m/h). Outside temp: 0C. In those conditions my current LEAF ranges 110-120 kms (69-75 miles).
To be continued...

[RegGuheert]

Ok. Thanks a lot!!! Tomorrow I,ll do it. First in LBW and then when it reaches 3.712 mV.
Is this CVLI something official in Nissan?

Yes, but not if we do it. Only if THEY do it. It is directly from the LEAF service manual.

Today the dealer technician told me that this cell was low but not low enogh to be considered a bad cell.

We have had several accounts of LEAF technicians doing CVLI at high voltages where it really does not apply. Again, the best way to know if that cell needs to be replaced is to calculate CVLI when the lowest cell is JUST below 3.712V. Post your LeafSpy picture here and we can give you specific advice about how to approach your dealership. Will it help? I suppose that depends on the dealership (and Nissan).

[avp]

I recommend that you run the car down to LBW and provide a screenshot of LeafSpy. It would be best if you get that picture JUST after the low cell drops below 3.712V. Then we can calculate whether or not Nissan believes that is a failed cell-pair. (This test is known as the Cell Voltage Loss Inspection (CVLI).)

Well, I did it. The low cell got 3.712 mV a few kilometers after LBW. LBW was at 20% (dasboard) while level 3.712 mV was reached when dashboard indicated 12%.



I was surprised because when dashboard was 12% SOC was 41,6 %



I also logged everything in the .csv file that LBA generates.

I started the test al 78%. The first strange thing was that turtle mode continued with battery charged at 78%



I turned off the car and turned it on again and the turtle mode dissappeared. But after 15 kilometers I turned off and on the car again and the turtle mode appeared again for a while.

Finally I reached home again after 29,5 kilometers (18,43 miles) with 12 % in the dashboard (from 78% to 12% in 18,43 miles). Wow!!



I am going to get the car back to the dealer on Monday. It is a possibility that they offer to me to repair this bad cell but I dont know if the rest of the battery may have had any extra effort due to this problem.

[vegastar]

Cell pair 4 is clearly unbalanced. It is red because the shunt order is wrong (it should be 8421). It is possible that with (long) time the other cells could discharge and reach the same level of CP4, but I think it is very strange to have this sort of unbalance. Probably CP4 is damaged with a relatively high self discharge, and it should be exchanged.

I know a case in Portugal of a 2011 Leaf that charged from 80% SOC to a 100% charge about 0.5kW.h (at the time there was no LS) and shortly after that the owner got a call from Nissan to exchange one module (it charged from dead to 100% about 14kW.h from the wall). The LBC certainly tried to balance the pack, but the self discharge in the bad CP was probably higher than the extremely low balance current of the LBC. After the exchange everythink became normal for a 2 year old pack (about 88% SOH).

If they don't exchange the module now, don't keep the car. It will be a PITA until Nissan finally accepts to fix the battery.

[avp]

I recommend that you run the car down to LBW and provide a screenshot of LeafSpy. It would be best if you get that picture JUST after the low cell drops below 3.712V. Then we can calculate whether or not Nissan believes that is a failed cell-pair. (This test is known as the Cell Voltage Loss Inspection (CVLI).

Once I have the information about this moment when min cell reached 3.712 mV, How can I calculate whether or not it is a failed pair?

[RegGuheert]

Nice job capturing the data *exactly* at 3.712V! That makes it difficult for Nissan to try to claim there is no issue.

Nissan's calculation for CVLI is somewhat convoluted, but I'll use their exact terminology so that OP can share it directly with the dealer in terms that should be familiar from the service manual.

CELL VOLTAGE LOSS INSPECTION

Description

The cell voltage loss inspection is performed is performed to identify cells that the cell voltage is on the decrease (although not judged a malfunction in DTC) and this may lead to a malfunction, if left stand.
This inspection identifies a cell voltage which is standard value or less when the minimum cell voltage is 3,712mV or less.
A module including a cell voltage identified by this inspection must be replaced with a new one to prevent malfunction.

Inspection Method

Skipping section explaining how to do this with CONSULT doing all the calculations.

CHECKING CELL VOLTAGE LOSS WITHOUT USING "WORK SUPPORT" OF CONSULT

1. PERFORM CELL VOLTAGE LOSS INSPECTION
With CONSULT
a. Select "DATA MONITOR" OF "HV BAT."
b. Check "MINIMUM CELL VOLTAGE."

Is "MINIMUM CELL VOLTAGE" 3,712 mV or less?
YES >> GO TO 3.
NO >> GO TO 2.

You are using LeafSpy instead of CONSULT and your MINIMUM CELL VOLTAGE is *exactly* 3,712 mV, so I will not type step 2 showing how to lower the voltage using the heater.

3. CALCULATE CELL VOLTAGE LOSS JUDGEMENT VALUE
With CONSULT
1. Check "DATA MONITOR" and record "TOTAL BATTERY VOLTAGE" and "MAXIMUM CELL VOLTAGE"
2. Calculate cell voltage loss judgment value.

Cell voltage loss judgment value = (2.5 x A - 0.144 x B) / 96
A = "TOTAL BATTERY VOLTAGE" (V)
B = "MAXIMUM CELL VOLTAGE" (mV)

NOTE:
The above equation of cell voltage loss judgment value is the simplified version of the following equation.
1. Calculate the average value of cell voltage by dividing "TOTAL BATTERY VOLTAGE" by 96 (the number of cells)

Average cell voltage = "TOTAL BATTERY VOLTAGE" / 96

Of course, LeafSpy gave you this value directly:

3.851V

2. Calculate cell voltage loss judgment value.

Cell voltage loss judgment value = Average cell voltage - ("MAXIMUM CELL VOLTAGE - Average cell voltage) x 1.5

From LeafSpy, we get:

Cell voltage loss judgment value = 3.851V - (3.861V - 3.851V) x 1.5 = 3.836V

>> GO TO 4.

4. JUDGE CELL OF VOLTAGE LOSS
With CONSULT
a. Record "CELL VOLTAGE 1-96" with "DATA MONITOR".
b. Check to see if there is "CELL VOLTAGE" which is less than or equal to the judgment value.

OK: Cell voltage loss judgment value < CELL VOLTAGE 1 - 96
NG: Cell voltage loss judgment value > CELL VOLTAGE 1 - 96

Is there a cell voltage which is the judgment value or less?
YES >> Replace module including cell voltage the judgment value or less. Refer to [EVB-153, "Exploded View"
NO >> INSPECTION END

3.836V is significantly higher than the voltage of your cell-pair 4, which is 3.712V. This is the clearest case of a failure of this test that I have seen. Since this is a new car, my opinion is that your cell-pair 4 has a manufacturing defect of some sort and needs to be replaced. (I have had a few occasions when I have had a cell fail this test, but the failure was much more marginal and was simply due to cell imbalance and later the issues corrected themselves, so I have not reported any issue to my dealer. In your case, the test was done in the optimum condition and one cell is clearly far below the rest of the pack.)

I have posted information in this thread which explains which cell-pairs are located in which modules and where they are located in the LEAF's battery. Basically, cell-pair 4 is in module MD2, which is located in the rear stack under the back seat, second from the right side of the car.

If you still have the option, I would recommend returning the car. If not, then it seems clear Nissan should replace the failed module under the terms of the warranty. Their own service manual says:

A module including a cell voltage identified by this inspection must be replaced with a new one to prevent malfunction.

[DNAinaGoodWay]

If they don't exchange the module now, don't keep the car. It will be a PITA until Nissan finally accepts to fix the battery.

+1

You did an excellent investigation.

[avp]

Nice job capturing the data *exactly* at 3.712V! That makes it difficult for Nissan to try to claim there is no issue.

Nissan's calculation for CVLI is somewhat convoluted, but I'll use their exact terminology so that OP can share it directly with the dealer in terms that should be familiar from the service manual.

CELL VOLTAGE LOSS INSPECTION

Description

The cell voltage loss inspection is performed is performed to identify cells that the cell voltage is on the decrease (although not judged a malfunction in DTC) and this may lead to a malfunction, if left stand.
This inspection identifies a cell voltage which is standard value or less when the minimum cell voltage is 3,712mV or less.
A module including a cell voltage identified by this inspection must be replaced with a new one to prevent malfunction.

Inspection Method

Skipping section explaining how to do this with CONSULT doing all the calculations.

CHECKING CELL VOLTAGE LOSS WITHOUT USING "WORK SUPPORT" OF CONSULT

1. PERFORM CELL VOLTAGE LOSS INSPECTION
With CONSULT
a. Select "DATA MONITOR" OF "HV BAT."
b. Check "MINIMUM CELL VOLTAGE."

Is "MINIMUM CELL VOLTAGE" 3,712 mV or less?
YES >> GO TO 3.
NO >> GO TO 2.

You are using LeafSpy instead of CONSULT and your MINIMUM CELL VOLTAGE is *exactly* 3,712 mV, so I will not type step 2 showing how to lower the voltage using the heater.

3. CALCULATE CELL VOLTAGE LOSS JUDGEMENT VALUE
With CONSULT
1. Check "DATA MONITOR" and record "TOTAL BATTERY VOLTAGE" and "MAXIMUM CELL VOLTAGE"
2. Calculate cell voltage loss judgment value.

Cell voltage loss judgment value = (2.5 x A - 0.144 x B) / 96
A = "TOTAL BATTERY VOLTAGE" (V)
B = "MAXIMUM CELL VOLTAGE" (mV)

NOTE:
The above equation of cell voltage loss judgment value is the simplified version of the following equation.
1. Calculate the average value of cell voltage by dividing "TOTAL BATTERY VOLTAGE" by 96 (the number of cells)

Average cell voltage = "TOTAL BATTERY VOLTAGE" / 96

Of course, LeafSpy gave you this value directly:

3.851V

2. Calculate cell voltage loss judgment value.

Cell voltage loss judgment value = Average cell voltage - ("MAXIMUM CELL VOLTAGE - Average cell voltage) x 1.5

From LeafSpy, we get:

Cell voltage loss judgment value = 3.851V - (3.861V - 3.851V) x 1.5 = 3.836V

>> GO TO 4.

4. JUDGE CELL OF VOLTAGE LOSS
With CONSULT
a. Record "CELL VOLTAGE 1-96" with "DATA MONITOR".
b. Check to see if there is "CELL VOLTAGE" which is less than or equal to the judgment value.

OK: Cell voltage loss judgment value < CELL VOLTAGE 1 - 96
NG: Cell voltage loss judgment value > CELL VOLTAGE 1 - 96

Is there a cell voltage which is the judgment value or less?
YES >> Replace module including cell voltage the judgment value or less. Refer to [EVB-153, "Exploded View"
NO >> INSPECTION END

3.836V is significantly higher than the voltage of your cell-pair 4, which is 3.712V. This is the clearest case of a failure of this test that I have seen. Since this is a new car, my opinion is that your cell-pair 4 has a manufacturing defect of some sort and needs to be replaced. (I have had a few occasions when I have had a cell fail this test, but the failure was much more marginal and was simply due to cell imbalance and later the issues corrected themselves, so I have not reported any issue to my dealer. In your case, the test was done in the optimum condition and one cell is clearly far below the rest of the pack.)

I have posted information in this thread which explains which cell-pairs are located in which modules and where they are located in the LEAF's battery. Basically, cell-pair 4 is in module MD2, which is located in the rear stack under the back seat, second from the right side of the car.

If you still have the option, I would recommend returning the car. If not, then it seems clear Nissan should replace the failed module under the terms of the warranty. Their own service manual says:

A module including a cell voltage identified by this inspection must be replaced with a new one to prevent malfunction.

Now, after your excellent research, I think it is clear that the car (the battery) is in bad condition. It is incredible that the dealer did an "official battery inspection and battery test" and they didn't find anything wrong. In my opinión spanish dealers are not prepared yet to manage this kind of cars. The personnel is not trained to do that and the result is not good at all. Owners use to know much more about EVs tan dealers.
Tomorrow We are going to give them the car back. If they offer us another one with similar cost and mileage we will get it. Otherwise we have to find other option.
Thank you very much for your help!!!