Battery Degradation of a high mileage Leaf

[Oostenrijker]

I was doing a third party battery diagnostic test this week, and I wasn't able to see Leaf Spy during driving. Because of the third party ODB2 battery diagnostic device.



After driving 212km's I reached 1% dash SoC and decided, this was far enough. As I had no idea of how low the battery SoC actually was. It turned out it was 14.5% and the abruptly drop in SoC this time did not happen at 8% SoC. But at 30% dash SoC, it all off a sudden dropped to 26% dash SoC when I got on the highway.



On ending the third party battery diagnostic test, I still had 4.8kWh left. According to my previous findings, about 4kWh I can't use. So to be on the safe side, I calculated 4.5kWh. Because my 40kWh battery, still has about 32.5kWh left. So I can use maximum 28kWh of that.

It just suprise me, this time no weak cell's showed: which I guess, can be explained because I didn't drive the battery empty in one go. So the BMS might have balanced it, between the trips I did the last couple of days.

But atleast I'm less concerned now: next Wednesday, I will get a battery test from Nissan. So then I will drop it with an low as possible SoC, which I can see when using Leafspy. But when not needed, I won't go below 10% dash SoC.

PS I haven't gotten the results from the third party battery diagnostic test yet: that will also calculate the SoH.

 

[Oostenrijker]

you are special to me gif

I dropped it this morning at the dealership, with 14% Leafspy SoC. I must respect Tesla Björn.... it takes quite some time, to run it safely even more empty. One one point I was driving cirkels around the dealership, to get it to this point.

Still don't know what they going say, but I think that I can life with these weak cells. In case they can't do anything with it. Because I try to treat the battery well, so I'm not to worried about it anymore.

 

[DaveinOlyWA]

Don't understand your comment about LEAF Spy. There is nothing to "trust" here. It is doing very little other than parroting data on the bus. It is not "generating" that 16% SOC, its simply reading it.

The other thing is Turtle isn't a line, a level, etc. Its a condition. Simply a voltage monitoring system designed to prevent excessive abuse of the pack. So no real way to predict its parameters since as you know, a single cell can trigger it. You can clear it "with" LEAF Spy or simply resetting the 12 volt.


What we should be asking is "Will all LEAFs with similar miles be this way?"

No, in fact most are not.

What, if anything, was done wrong, not done, etc, ?

Impossible to say as it would appear you have little info on how the car was charged which is likely THE only thing that can be fixed since WE have total control over that.

Either way, knowing now only allows you to make better decisions with your next EV. This one is done. Having issues at low SOC is not unusual but you have challenges accessing nearly 1/5th of your range which is well out of bounds for most of us.

So will it work? That is up to you to decide. You will be forced to live in a higher SOC range due to the weaker cell issues which is still a pretty decent range but...

 

[Oostenrijker]

My Leaf has gotten a Battery Test today: and the data from Leafspy is quite accurate. But surprisingly, the result of test was good. It said my battery was in a good state, and the degradation was caused by frequent fast charging and high energy consumption aka fast driving.



So typical business lease driver, the previous driver of this Leaf: because I tend to drive as an snail, maximizing the range. But I'm quite sure, the previous driver didn't....



Anyway, I'm not so worried anymore about these weak cells. When I first discovered it: it was like 14 of them? Now I only see three. Which I guess, charging to 100% every now and then might be good to balance the pack.

And I plan to not go lower anymore then 10% dash SoC, which is about 20% Leafspy SoC. Because I would like to drive this Leaf a bit longer, then only one year. Maybe after 2 years I might look for another EV?

Perhaps an 59kWh/62kWh, but I think that it won't be a big issue for me, to not go lower then 13% Leafspy SoC. Which I would only do while using Leafspy. But I'm totally fine, with not being able to use about 12% from the leftover capacity.

I can life with it: the battery test from Nissan, actually turned out as good. But that was kinda expected.

 

[DaveinOlyWA]

My Leaf has gotten a Battery Test today: and the data from Leafspy is quite accurate. But surprisingly, the result of test was good. It said my battery was in a good state, and the degradation was caused by frequent fast charging and high energy consumption aka fast driving.



So typical business lease driver, the previous driver of this Leaf: because I tend to drive as an snail, maximizing the range. But I'm quite sure, the previous driver didn't....



Anyway, I'm not so worried anymore about these weak cells. When I first discovered it: it was like 14 of them? Now I only see three. Which I guess, charging to 100% every now and then might be good to balance the pack.

And I plan to not go lower anymore then 10% dash SoC, which is about 20% Leafspy SoC. Because I would like to drive this Leaf a bit longer, then only one year. Maybe after 2 years I might look for another EV?

Perhaps an 59kWh/62kWh, but I think that it won't be a big issue for me, to not go lower then 13% Leafspy SoC. Which I would only do while using Leafspy. But I'm totally fine, with not being able to use about 12% from the leftover capacity.

I can life with it: the battery test from Nissan, actually turned out as good. But that was kinda expected.

Its good you have the data so you can make your own guess because that is all Nissan gave you. Their statement "due to excessive DC charging and fast driving" is quite generalized at best.

Like any charging procedure, there is a right way and a wrong way and this guy did it the wrong way. The # of DC sessions is far from excessive so it would appear he routinely charged to a high SOC creating heat. Its the combination of the two that is more dangerous.

Without TMS, the LEAF suffers on both ends of the spectrum charging both cold and hot packs; neither of which is a good thing especially in the way Nissan handles it.

Most EVs when cold, the DC charge starts slowly and then ramps up as the pack warms. The LEAF starts at or near max speed and simply hits the knee sooner instead. Obviously done for marketing purposes to the undeniable cringe of the engineers...

As far as your larger pack options; even if you don't need the range much, it is a HUGE advantage when maintaining the pack for the long haul. Living in the middle is much easier when the middle covers a lot of territory.

 

[Oostenrijker]

As far as your larger pack options; even if you don't need the range much, it is a HUGE advantage when maintaining the pack for the long haul. Living in the middle is much easier when the middle covers a lot of territory.

Yes an 62kWh/59kWh Leaf, would definitely give me that extra range that I'm now sometimes missing. Just on the moment: I bought this Leaf in april. The value has for sure dropped since then.....

And I'm expecting, these 62kWh/59kWh to drop further in value as well. It's just about the TCO, which will drop when I have driven more km's.

But for now I'm actually happy with the car: it just got a brand-new windshield. The recall been done. So I won't look to much into Leafspy anymore, because it drives a man crazy.

Before getting Leafspy, I didn't give a single though: about my SoC went at 8% so quickly down. I just thought, it must be because this is an high mileage Leaf. Only I'm sure, when it was treated right? It would definitely not had these "weak cell's" I guess.

The only thing I can do now: is atleast treat the battery good by myself, so I can minimise further degradation.

 

[DaveinOlyWA]

As far as your larger pack options; even if you don't need the range much, it is a HUGE advantage when maintaining the pack for the long haul. Living in the middle is much easier when the middle covers a lot of territory.

Yes an 62kWh/59kWh Leaf, would definitely give me that extra range that I'm now sometimes missing. Just on the moment: I bought this Leaf in april. The value has for sure dropped since then.....

And I'm expecting, these 62kWh/59kWh to drop further in value as well. It's just about the TCO, which will drop when I have driven more km's.

But for now I'm actually happy with the car: it just got a brand-new windshield. The recall been done. So I won't look to much into Leafspy anymore, because it drives a man crazy.

Before getting Leafspy, I didn't give a single though: about my SoC went at 8% so quickly down. I just thought, it must be because this is an high mileage Leaf. Only I'm sure, when it was treated right? It would definitely not had these "weak cell's" I guess.

The only thing I can do now: is atleast treat the battery good by myself, so I can minimise further degradation.

Gen 2 BMS programming has changed dramatically so you will see adjustments every 3 months keyed to your build date. Adjustments can go down (a little or a lot) stay the same or go up (The ONLY time this happens)

So just because you saw a drop doesn't mean it was a loss of capacity. There are many thoughts (actually there isn't) on why Nissan has chosen this route with the most common being that "measuring real SOH in real time is very hard to do"

and so on.

I have "nearly" come to the conclusion that Nissan has created a hidden buffer that LEAF Spy cannot see as a result of usage. So modest drivers may see "degradation" when in fact, its simply a larger hidden reserve created based on very modest usage.

Now why I think this is a quite the explanation which I will withhold at this time at least until Fall 2024.

 

[DougWantsALeaf]

Making us wait a whole additional year?

 

[fester]

I do any occasional check with LeafSpy, but the one thing I look at is cell balance. If its my typical 10-15mv, all is probably well. The other thing is the 12v battery voltage, which has been good for the last year and a half on my 22' SV+. If I want to keep tabs on the 12v other than leafSpy, I'll attach a small voltage data logger and run for a week or so...to see whats it's doing when I'm not looking .

 

[Oostenrijker]

I do any occasional check with LeafSpy, but the one thing I look at is cell balance. If its my typical 10-15mv, all is probably well. The other thing is the 12v battery voltage, which has been good for the last year and a half on my 22' SV+. If I want to keep tabs on the 12v other than leafSpy, I'll attach a small voltage data logger and run for a week or so...to see whats it's doing when I'm not looking .

Well it is most of the time like that, but it gets a little higher, when the pack is depleted for almost 60% ( so 40% left ) and the mV difference stays below 100mV. Only around 8% it might go above 100mV and around 12% it could reach 600mV ( Leafspy SoC).

Actually last week, I also curiously found out: when I did this battery test: I didn't drive it in one go empty, and afterwards at 14.5% the difference in voltage was only 61mV.

Also no weak cells showed: so when I saw this, I was already more eased at mind. However, I'm totally aware that with my high mileage Leaf. The pack gets out of balance so much around 12% that I one time experienced Turtle Mode there. Although I purposefully tried to go down as much as possible.

Now I think, in order to preserve the battery: I should stop using Leafspy. When using Leafspy, I tend to drive further empty then I should. Or I keep looking at the data, and driving myself nuts. But it's a fact, I haven't been stranded yet with the car.

I did learn some more things though: once the battery gets emptier, it's best to drive as an snail. Because I did see it going from 30% to 26% all of sudden, when I accelerated. But once I get to cruising speed, it's gets back again.

Saturday I'm going do another roadtrip to Austria: I kinda see these trips as an challenge. If there is really something seriously wrong, then I guess I wouldn't make it. But I don't worry about it.

 

[DaveinOlyWA]

Making us wait a whole additional year?

You probably know where I am headed since I have mentioned it several times but its hard to make conclusions when you are looking at 6 data points and 2 of them are somewhat inconclusive. Either way, I am guessing that better battery chemistry has done nothing but lengthen the timeline it will take to see a lot of things concerning battery health.

 

[DougWantsALeaf]

From my small sample set, my 4 1/2 year old Leaf Pluses appear to have a very similar degradation curve to every Tesla owner I know that watches their battery. Small sample, but still.

 

[dang10010]

Reading this thread makes me want to baby my newer battery. The symptoms of battery cell imbalance suck, that's exactly what my 30 kWh battery did before it got replaced with the 40. It was much worse during winter, under 40 F and you'd have to drive it slow everywhere, under 20 F and it was instant turtle and you could never floor it. The next time my car is at 20% I'll check the battery with Leafspy, it's about 6 months old.

 

[Oostenrijker]

Reading this thread makes me want to baby my newer battery. The symptoms of battery cell imbalance suck, that's exactly what my 30 kWh battery did before it got replaced with the 40. It was much worse during winter, under 40 F and you'd have to drive it slow everywhere, under 20 F and it was instant turtle and you could never floor it. The next time my car is at 20% I'll check the battery with Leafspy, it's about 6 months old.

Thats what I'm doing now: last time I drove 40km/h where I was allowed 70km/h, and lucky it was in the middle of the night. But by doing so, I managed a stable drop in SoC and arrived with 5% at the fast charger. Instead of obsessively using Leafspy, I now stop using it and try to stay above 10% SoC knowing its about 20% in reality. Now whenever I see I might not make it, but there isn't a closer fast charger available, then I start hypermiling the sh*t out if it. And when needed and safe to do, then I will drive as slow as possible as well: because that maximises the range and might give the BMS a chance, to balance the battery.

I know now: when low SoC, don't drive to fast as it will put more pressure on the BMS. Actually after my last roadtrip to Austria, I'm quite happy with this Leaf again. Only twice I encounter a not working fast chargers, but that wasnt a issue as I had enough range.

 

[Oostenrijker]

I finally got the result from Aviloo Battery Diagnostics: the degradation test wasn't done in one go, so perhaps that's why the voltage difference wasn't as high at the end of the test?

But nevertheless, the battery expert from Aviloo told me some shocking news. Honestly I already knew it all time. It's not without reason, I have been stressing so much about this issue?! Once I found out about the weak cells.

The expert, told me: it's for sure the battery pack going need a repair on the short time. Conforming for me, what I knew all the time already. Overall state of the battery pack is quite bad, and it has suffered heat damage from a combination of often quick charging and fast driving.


So I have escalated things and now I'm demanding a solution from the Nissan dealer: I don't care what Nissan says, or that the battery warranty has expired. Because in my country the Netherlands, we have very good laws concerning used cars.

Which means from the date from purchase, I have one year warranty. Sadly they seem to be ignoring me, ever since I shared the result with them on Monday? It's Friday and still no response back, which just makes me furious.

I see several options: stop babying the battery pack, and always charge to 100% and drive as empty as possible. Yes one shouldn't do it? But what does it benefit me, that by babying it? So staying between 20 and 80% and this way extending it's lifetime? There is no benefit for me, other than a high cost for repair when it dies after april 2024.

But I hope all of this isn't needed, and that the will acknowledge the issue: I did some rough calculations. If I actually have a SoH of 84% as shown in Leafspy, then my real useable capacity is between 68% and 70% as I can't use 12.5% to 18% of the leftover capacity.

SoH doesn't say a f*** when you can't use the remaining capacity for 100% totally. Ofcourse one shouldn't do it frequently, but I think incidentally I should have been able to use 90% to 95% of the remaining capacity. But I didn't get further than 12.5% and at that point, I discovered Turtle Mode.

A good chance, now in the winter: the batter will die: I see the dash SoC jumping from 50% to 40% when driving on the highway. This I have reported to the Nissan dealer as well. No response at all, so I even have escalated it to Bovag. Which is the organization, handling the used car warranty which you can buy.

 

[Oostenrijker]

So glad I ditched my plans years ago on the Leaf and got a real EV I could trust.........made in America and by TESLA. Love it. Range, power, acceleration and ALL the tech and above all the Supercharging infrastructure. I already know before I leave the house on a road trip all the Superchargers I am going to visit, how long, what the cost will be and how many stalls are at the location and how many are available. Oh, yes the Tesla NACS is the most reliable charging system available and keeps getting better and quicker now with Version 4 coming on line NOW.

Tesla clashes with the values we hold deerly in Europe: that's why in Sweden, Tesla is being boycotted. So perhaps the battery technology from Tesla is better?

But I rather don't trade my soul to the devil, and if I would choose another brand: it would be either Kia or Hyundai. Sadly they are quite expensive used, so the Leaf is still the most value for money.

Or BYD and MG are also offering very good EV, and a price point hard to compete with. If my wife wasn't against Chinese EV's, I could totally imagine getting an MG4 as it's quite similar to a Leaf.

I don't like SUV's....

 

[Oostenrijker]

Mine high mileage Nissan Leaf, was shortly show in a YouTube video: next year, there going be a full video about it online. Although in Dutch, so the average American wouldn't understand a thing.... even if there ancestors are from the Netherlands.

 

[DougWantsALeaf]

This Plus driver is at 170K miles and original brake pads.

 

[SageBrush]

The SoC percentage takes the sum of cell voltages, while the GiD percentage multiplies the lowest cell voltage * 96. This has the effect of taking into proper account the weakest cell. I don't think those 3rd party tests you are doing are taking the weak cells into account the way they should.

One other comment: I expect your weak cells to age quite a bit faster than the rest of the pack. I frankly doubt you will find the car meets your needs in two years. You get to gamble: how much will the car be worth with a defective pack ? Will Nissan honor the battery defect warranty at all, or only well into the period where the car is not meeting your needs ? Your presumption that the extended warranty you bought for 500 Euros takes care of you strikes me as ... naïve

I don't know if DC fast charging will degrade the weak cells faster, or how much faster. I do know that I would not sit around twiddling my thumbs while charging at 3 kW on trips if I had any choice in the matter.

My advice: Get out of this CHAdeMO EV with a bum battery as soon as you can afford it. For now, it still has value as a local only car that AC charging can satisfy, and with an owner who can be patient while Nissan jerks them around about the warranty.

 

[Oostenrijker]

Your presumption that the extended warranty you bought for 500 Euros takes care of you strikes me as ... naïve

I bet you are from the United States, where people have to tip in restaurants? Where there is no health insurance, no buyer protection when you buy stuff online etc.

Then ofcourse you would think it's naive: because in the United States you don't have such rights. Believe me, my used car warranty would cover it.

Only I might need to make it throw a DTC: Nissan makes you go through loopholes, I saw enough YouTube videos on this in the weekend. One guy from Canada, kept erasing his DTC...

But that's exactly what would make my position stronger: once they DTC is there, they can't deny anymore that my battery pack doesn't have problems. If they then would keep denying, I can open a dispute for € 127 but I guess that won't be needed.

So I shouldn't sell it or trade it in right now, because I still got four months of warranty left. And I most likely just need a cold winter day, because it acts up already as well when it's a quite warm winterday.

I want to get rid of the car ofcourse, but won't do as long as I still got the used car warranty. And also the trade in value is only € 9000 and I paid in april 2023 € 18000 totally, so trading in isn't really an option.

Because I don't have € 9000 lying around: for about the same money I paid, I saw an 2020 Tekna 40kWh with only 40.000km on the odometer. It feels stupid, but I'm just in bad luck because the EV car market crashed and also prices of new EVs went down.