Seems a lot - others here are hopefully more experienced than I am. But 2 thoughts:
1) Try get power pretty low (well below 5%, ideally tortoise mode if you can driving round the block) and then fully charged. May give BMS a chance to sort the balance.
2) Kinda remember that Nissan servicing did a battery status report? Would be interesting to see how much of the service history you have. Getting an off the cuff battery status from a Nissan dealer now without a service is probably more than its worth.

As you say protect your return for refund rights. But may not be as bad as you fear.

PS - woah - you say 24k miles but LeafSpy says 15140 - run away now!
OTOH lots of granny charging there and only 21 QC which would normally be a plus in my book. Try a couple of 100% granny charges and see what the BMS can do.

PPS - are you in KM? see this thread

https://www.speakev.com/threads/leafspy-shows-different-odo-mileage-from-the-dash-odometer.185571/?post_id=3624322&nested_view=1&sortby=oldest#post-3624322

 

Thank you, dukla2000!
Indeed LeafSpy thought CAN odo is in km. Changed it in settings to miles and it now shows 24386 mi, matching what is shown on the dashboard:

A few other things I should probably mention about the car if any of these matter:
1. The dealer claimed that the car was part exchange from an a elderly couple.
2. It sat with the dealer for about 2 months (probably was priced too high originally - they dropped it by £2k by the time I bought it)
3. When we did a test drive and bought it 3 days ago it showed ~55% charge.

 

I was going to ponder the high L1/L2 charge count previously, let me do it now as think consistent with "elderly couple" with range anxiety!

62KWh should have range at least 150 miles on 80% charge. (My 24KWh gets 60 miles on 80% charge and I am below 80% SOH as well.) So 674 L1/L2 charges enough for 101k miles! Seems to me they often put it on charge whether it needed it or not. I think running as low as you can and fully charging at least once, if not twice, may give the BMS a chance to sort that cell.

As previously I am happy to be corrected by someone wiser. (I can't remember the logic for a LEAF whether the BMS top and/or bottom balances!)

Also - if it is a Nissan dealer ask for them to do a battery report (free!). But although ~100mV seems scary I think it may well improve a lot and not be a big deal if slapped a bit!

 

Hi all,

New here and to EV in general.
I just bought a 2020 e+ Tekna 62kwh with 24k mileage. It drives nice and shows full battery health in the dashboard but on a recommendation from a colleague I bought an OBD2 tester and LeafSpy Pro to check the real state of the battery. It shows ~100mv difference for one cell:
View attachment 209551

Reading around I understand it is quite bad. Is this cell is expected to degrade further?

I understand the Nissan UK warranty for the battery is pretty much useless to the point that it won't cover a heavily unbalanced/degraded cell and especially a failed cell.

So my question really is: are there more leaf owners with a similar state of a battery without experiencing major further degradation or those who saw there battery state degrading quickly with such cells?

If this is a sign of the battery degrading quickly, since I'm still under 31 days since the purchase then I'm probably better reject the car and get a full refund.

Thanks for any insight!

Sometimes over time or if a LEAF has been left sitting around for a while unused, one or more cells which may have slightly different characteristics to the rest can drift out of balance. The LEAF's balancing ability is very small and won't ever be able to pull such a cell back in line with the others if this happens and over time it will diverge further. This causes the battery to shut off when this single cell hits it's lowest safe point which will effectively limit your range considerably as well as making the car unpredictable under load at lower states of charge.

I bought such a car a couple of years back with a very similar cell and successfully pulled it back into line with the others manually, but I'm a mad scientist type with an electrical engineering background, I suspect you're very unlikely to want to do this as it involves dropping, opening the battery, then manually balancing the offending cell, resealing and reinstalling the battery!

If you have the option, reject the car and get yourself another with a well balanced pack.

 

Before discharging to a low level, I would L2 charge to 100% and leave it charging until fully complete a few times and use the car gently for slowish (low power) but reasonably long journeys so that the feeble cell balancing system has a chance to do something. Discharging to a low level when one battery cell is low is very likely to damage that cell significantly more.

 

There are plenty others for sale. From what I have seen your assessment of the Nissan warranty is correct - and even if they did the repair under warranty then you would be without the car for weeks if not months. On that basis if I were in your position I would get my money back.

 

IMHO the cell is too low to recover with normal balancing, there is always the potentially when under load, that the voltage in that cell could drop below a certain level that would cause the whole pack to shut down.

Not worth the hassle and worry, get your money back, plenty of more fish in the sea.

 

just hope the supplier made an error in selling the car and wasn’t trying so sell a lemon. How many times have you done the reading and have you used your OBD 2 on another car to check irs accuracy.

hope the supplier is sensible and gives you back your money if these readings are correct.

 

If you're concerned then take it back, but it would be interesting to do a couple of charge cycles to 100% at reduced current to see how it balances out. Measure the cell balance at 100% and then at say 25%.

 

Thank everyone for suggestions!
And based on those, I'll charge it to 100% and let it sit on charger after that for a few hours today. Tomorrow I'll have a ~160miles round trip. After that I will see what is the state of the cell. If it is the the same, I will start the process of rejecting the car.

 

...have you used your OBD 2 on another car to check its accuracy.

An OBD dongle, and Leaf Spy, don't measure anything[1] themselves and cannot be inaccurate. They display the digital reports from the battery management system (LBC to Nissan, BMS to everyone else), which has its 96 voltage sensors wired in to every cell (pair) in the traction battery. Comparing the readings from multiple dongles and Leaf Spy installations will not help with the accuracy or truthfulness of those measurements!

The LEAF's balancing ability is very small...

True! The red bars in the Leaf Spy plot show the cells where the BMS has connected tiny bleed resistors to lower their charge.

Leaf balances a little all the time its being used: when switched on, the BMS identifies the highest-voltage cells and switches on the bleed resistors which draw a few milliamps for them. They stay on until the car's switched off again, whether half a minute or a couple of hours. This has slightly more effect than the square root of nowt. Then when charging from about 99% to 100%, the charging rate is slowed right down and the bleed resistors are adjusted to try to charge the lowest cells a bit more than the highest (called "top balancing" I think). That also has only a small effect.

Longer switched-on times -- such as plenty of non-motorway miles -- may help, and occasional charging to 100% may help, but it looks to me as though cell 18 has a manufacturing fault and will never catch up with the others -- Favguy is right. I'd talk to the garage who sold it and consider rejecting the car as a lemon. Or if you like the car, negotiate a battery-out cell balance or a substantial refund.

[1] The dongle does have a 12V system voltage measurement built in, and that's not brilliantly accurate. It can be calibrated against a reliable multimeter, but I'd cut out the middleman and measure the 12V voltage with my meter directly.

 

So I had a 160miles trip today - 80miles each way on motorways. Started from fully charged - restarted charging a few times to see if it makes any difference to the cell 18. No difference. At fully charged the diff was ~100mv. The estimated range was 240miles. I was driving in ECO mode with the speed 60-65miles. around 15miles had 50miles limit. Was monitoring the diff while driving and it stayed pretty much the same fluctuating between 100mv and 110mv. Arrived to the destination and the car was parked there for ~4 hours. The average consumption was 4.4miles/kwh. At the start of the return journey LeafSpy showed:

And on the return journey actually started falling. So here are a few screenshots along the way:

And then it started to fluctuate around 42mv:

If I heavily accelerated it would jump to ~50mv.
The lowest I saw it dropped to was 34mv:

When I parked at home it showed:

On the way back I deactivated ECO and was doing 65-70miles (again with ~15miles limited to 50miles). I was heavy on the pedal when overtaking and the average consumption was 3.9miles/kwh
At the end the dashboard showed 16% battery remaining, 37miles range, 158miles driven.
Later today I'm going to drive it to 0 (dashes/turtle).

Anything positive/negative can be deduced from the above?Any point in trying rapid charging when I've emptied it? Or should I do slow charge again?

 

So I had a 160miles trip today - 80miles each way on motorways. Started from fully charged - restarted charging a few times to see if it makes any difference to the cell 18. No difference. At fully charged the diff was ~100mv. The estimated range was 240miles. I was driving in ECO mode with the speed 60-65miles. around 15miles had 50miles limit. Was monitoring the diff while driving and it stayed pretty much the same fluctuating between 100mv and 110mv. Arrived to the destination and the car was parked there for ~4 hours. The average consumption was 4.4miles/kwh. At the start of the return journey LeafSpy showed:

View attachment 209641

And on the return journey actually started falling. So here are a few screenshots along the way:

View attachment 209642
View attachment 209643

View attachment 209644

View attachment 209645

View attachment 209646

And then it started to fluctuate around 42mv:

View attachment 209647

If I heavily accelerated it would jump to ~50mv.
The lowest I saw it dropped to was 34mv:

View attachment 209648

When I parked at home it showed:

View attachment 209649

On the way back I deactivated ECO and was doing 65-70miles (again with ~15miles limited to 50miles). I was heavy on the pedal when overtaking and the average consumption was 3.9miles/kwh
At the end the dashboard showed 16% battery remaining, 37miles range, 158miles driven.
Later today I'm going to drive it to 0 (dashes/turtle).

Anything positive/negative can be deduced from the above?Any point in trying rapid charging when I've emptied it? Or should I do slow charge again?

Yes, very helpful. This clearly shows that the out of kilter cell is of a lower capacity than the others as the difference in voltage drops along with the state of charge. If it was just out of balance, the voltage difference would stay roughly constant as the SOC drops. As a lower capacity cell it has aged/degraded much faster than the rest of the pack and can never be balanced to match the others, even manually, so would need changing out for the battery to be able to function at full capacity.

Time to reject the car.

 

Drove it to zero. It was fluctuating around 55mv while I driving around last 40miles. When I parked it showed:

I will charge it overnight and see what happens with the cell. If it goes back to ~100mv then as advised I'll be rejecting the car after receiving docs from DVLA.

 

It is charging now and up to 4%. The diff is fluctuating between 26mv and 32mv.

 

If the cell can be salvaged, (again though, the car won't pull it back without manual involvement) the difference should remain constant at around 30mv, once you get back to full. I'll wager it'll be back at 100mv or so lower.

 

I now wonder what evidence I can give to the dealer for rejecting the car - I'm sure they will dismiss LeafSpy, and even if they considered it, it now now shows reduced (below 40mv) diff at fully discharged SOC. There is no range shortage, it doesn't show any sudden drop of charge/range when heavily accelerating up a steep hill. Even though I bought it on finance, I bought it in person so apparently no 14 days cool-off period. I'm screwed

 

Ah, if there was no specific agreement that you could return within a given time for any reason, you might be screwed. The car is still perfectly functional and will work fine at least for quite some time yet as it is, you will just have a reduced range due to the BMS working based on the lower capacity of the weak cell.

I know it doesn't help in this case, but the moral of the story is to always check with Leafspy before buying, unless you're covered by the distance buying rules that allow a return for any reason within 14 days.

 

At this moment I can only praise the way the dealer handled it. We returned the car on Sunday and formally rejected it. We received written confirmation that the car was returned. Today we had a confirmation that they raised an "unwind request" to the bank for the car loan and that our deposit will be refunded once we send them the copy of the car's logbook(V5). All seems good.

 

Fantastic news, I'm almost amazed. Nice to see there are still some honest dealers around who will do the right thing!

 

The next owner may not realise there's a problem until they run the battery down low and wonder why the range drops suddenly. 😕

 

Sadly, you're probably right, the majority of buyers who don't frequent forums will be oblivious that Leafspy even exists. They'll most likely just use the car for some time unaware anything is amiss.

 

Did a version of the Leaf60 pack not have a known issue that could only be cured by a cell replacement? I'm sure there was something on Dala's channel. Cheers

 

Glad you are sorted. Good to hear of a good honest car dealer.

 

You may be able to recover some cell performance, but in will only mask the issue and make it harder to return. Get the supplier if with warranty etc.. to take car back or have faulty cell replaced.
It'll catch up sooner or later & you'll be stuck with at worse a battery fire.

 

Can anyone say why in some graphs the dud cells are showing red and some graphs they are showing blue, so there is a bleed attached some of the time even though the voltage is well below surrounding cells ?

 

I just ignore the colours on Leafspy, they don't seem to make sense at all a lot of the time.