Battery percentage drops erratically on acceleration

[pprasanth]

My 2018 Nissan Leaf SL (40KW battery) has been an excellent car for 5 years. I bought it in August 2018. For the last 3 months, there is an erratic behavior in battery. From 100% to about 65%, it is good. When it goes below that, a slight elevation, or acceleration drops the battery levels by 5% or above drastically. Sometimes, it drops nearly 30% in less than 2 miles. But, it recovers about some of it when slowing down. Overall, on an average, battery lasts for about 90 miles (down from 120 miles just about 3 months back before this problem started).
LeafSpy Reading (on most recent trip) : distance: 26.0, Energy: 6206, Gids: 76, SOH : 86.10%

I took the car to the dealer. They said my 12v battery is weak, and it was at 80% efficiency, and advised me replace the battery. I replaced the 12v battery. But, the problem persists. I lost trust in the dealer. Need advise please.

 

[LeftieBiker]

Your problem has all the hallmarks of a battery with one or more weak cells. You need to check it with LeafSpy Pro and a suitable dongle like the one in my signature. Basically, the weak cells are dropping in voltage too much under load, causing the Battery Management System to cut back on power and revise the state of charge reading.

 

[Oostenrijker]

Try to record this, when it happens again? I'm having the same issues, and currently the dealership is in contact with Nissan. Because I want a solution.

Actually it's funny: I bought a Nissan Leaf, thinking these are super reliable. Just like any other brands, but seeing things like this happening makes very sad.

 

[cornbinder89]

Try to record this, when it happens again? I'm having the same issues, and currently the dealership is in contact with Nissan. Because I want a solution.

Actually it's funny: I bought a Nissan Leaf, thinking these are super reliable. Just like any other brands, but seeing things like this happening makes very sad.

All makes and models have their problems. Nissan's CVT are known to be problematic. I have a Toyota Camry, that is "supposed" to high on reliability charts. In a way it is, but I also have to be constantly addressing something on it.
I think there are issues that are somewhat common, but by no means happen to every car.
Individual battery cell failure, is an excellent example. It pops up often enough to be known, but at the same time, the other cells in the battery do not all fail. To the owner of such a battery pack, it is little comfort to know most of the cells are unaffected. From an engineering prospective, why some fail and others do not, even in the same pack, and seeing all the same conditions, it can be very difficult to resolve. One can't say the design is the problem or all the cells would fail.
Most likely it is "production tolerances" that cause one pack to be effected before all the rest. Little comfort to the owner, I agree.
I see things fail I my Toyota that "don't normally fail" and it is of little comfort to me my failure is an outlier.

 

[pweisel]

Having the same issue on my 2020 SV (40kw) with 50k miles. It happens when the battery is around or below 50% charge, I am driving at 50+ mph, and especially when on my daily commute 400 ft elevation incline.

I recorded it on my phone and brought the car to the dealer. Fluctuation was about 15% over the course of 2-3 miles. Largely "regained" on the downhill. Nissan kept my car for a week, trying to replicate my recording, but could not replicate it enough for them to authorize a fix. No codes are being thrown.

Now a month later I'm getting 30% fluctuations. I'll record again and bring it in again.

My dealer said they have seen a few of these, and to just bring it back when it gets worse. I'll bring it in again in the near future. In my case, I think the big incline, and thus strain on the battery, is what triggers it. So far they have been supportive and did not charge for checking the car. They predicted they would eventually have to fix it. I have plenty of warranty left and they told me not to worry about it. This is our 2nd Leaf. Drove 90K on our 2013 with out any issues. Been saving a fortune on fuel for a decade!

Does anyone know:

The fluctuations shown on the gauge - how do they relate to the actual state of the battery? Since the % charge is "regained" on the downhill, I ASSumee it was never gone to begin with? I am hoping not to get stranded before I have a chance to bring it in again.

Pete

 

[LeftieBiker]

The state of charge is read based largely on the cell voltages - probably the average of them. So when the voltage of one or a few 'sags' and causes the displayed SOC to drop, it's just an inaccuracy caused by the weak cells' drop in voltage. You still have, more or less, the same state of charge

 

[hornstudio]

Nissan needs to develop a software update asap which makes the BMS calculate much slower than it does now and problems are solved. Just like the temperature gauge. But when you are on a highway for a longer period you might start getting frightened.

 

[Oostenrijker]

The state of charge is read based largely on the cell voltages - probably the average of them. So when the voltage of one or a few 'sags' and causes the displayed SOC to drop, it's just an inaccuracy caused by the weak cells' drop in voltage. You still have, more or less, the same state of charge

That's true, but it isn't normal behaviour of the battery. Sooner or later you going left stranded near the side of the road, and the Nissan dealership did nothing. Even though you send them proof.

They don't accept Leafspy recordings: but you can see in Leafspy, what the voltage difference was on the moment. And I guess it must be very high, because else it wouldn't happen



So I'm trying to capture it, when it happens with my Leaf: but haven't been able yet, to also capture with Leafspy what happens while the dash SoC drops in just a few seconds from 50% to 40% for example.

But on the way back, I recorded my whole journey: the max speed, was the whole way 50km/h so no chance to reproduce it. Just I was able to spot this spike in my recording, but my weak cells are actually on the left...

I guess weak cell's, eventually effect other cells in the pack as well. Because while idling, it's still the weak cells on the left with the lowest voltage.

 

[LeftieBiker]

"The state of charge is read based largely on the cell voltages - probably the average of them. So when the voltage of one or a few 'sags' and causes the displayed SOC to drop, it's just an inaccuracy caused by the weak cells' drop in voltage. You still have, more or less, the same state of charge

That's true, but it isn't normal behaviour of the battery. Sooner or later you going left stranded near the side of the road, and the Nissan dealership did nothing. Even though you send them proof."

Oh, I wasn't saying it's normal behavior. I was responding to the concern that maybe when the reported SOC drops a lot, that charge is lost. It isn't.

 

[Deleted member 37802]

Having the same issue on my 2020 SV (40kw) with 50k miles. It happens when the battery is around or below 50% charge, I am driving at 50+ mph, and especially when on my daily commute 400 ft elevation incline.

I recorded it on my phone and brought the car to the dealer. Fluctuation was about 15% over the course of 2-3 miles. Largely "regained" on the downhill. Nissan kept my car for a week, trying to replicate my recording, but could not replicate it enough for them to authorize a fix. No codes are being thrown.

Now a month later I'm getting 30% fluctuations. I'll record again and bring it in again.

My dealer said they have seen a few of these, and to just bring it back when it gets worse. I'll bring it in again in the near future. In my case, I think the big incline, and thus strain on the battery, is what triggers it. So far they have been supportive and did not charge for checking the car. They predicted they would eventually have to fix it. I have plenty of warranty left and they told me not to worry about it. This is our 2nd Leaf. Drove 90K on our 2013 with out any issues. Been saving a fortune on fuel for a decade!

Does anyone know:

The fluctuations shown on the gauge - how do they relate to the actual state of the battery? Since the % charge is "regained" on the downhill, I ASSumee it was never gone to begin with? I am hoping not to get stranded before I have a chance to bring it in again.

Pete

It starts mild and then will begin to wildly fluctuate as the battery cell becomes less responsive -- I can go from 100% to "--" in under a mile at 15% incline, and I can also drive for 30 miles on a flat grade with zero impact or changes. I had driven the same route over and over with varying results - swinging from a 10% loss up to a 100% loss in incredibly short distances at incline -- finally - the battery became too wildly unpredictable to drive safely at all.
Tech at the dealer said not to run it to zero without letting it self calibrate (by pulling over,,, allowing the bad cell to reset itself) - if you let it zero out it won't be able to recover ( 'they think').
Stress to your dealer the battery is getting worse and its causing you to change your driving habits - stress that it is dangerous to constantly monitor the battery level and adapt to its needs to move your vehicle down the road..... keep a log of 'swings' or 'yo-yo' of the battery and the range on each trip. Log the route grade / elevation changes by using a site like this Flattest Route - all of this should move you to the front of the battery warranty line good luck!

 

[Oostenrijker]

Oh, I wasn't saying it's normal behavior. I was responding to the concern that maybe when the reported SOC drops a lot, that charge is lost. It isn't.

That's true, then we misunderstood each other: that makes driving with Leafspy more pleasant, you can see actually the energy isn't lost.

 

[dwl]

Nissan needs to develop a software update asap which makes the BMS calculate much slower than it does now and problems are solved. Just like the temperature gauge. But when you are on a highway for a longer period you might start getting frightened.

I have experienced this problem on a 2018 during a long steep climb when battery cold and slowing down the BMS calculation is not an answer. The problem is the weaker cells contain charge but cannot deliver sufficient power to meet demand and the cell voltage drops. When the cell voltage drops too low then shutdown will occur. In my case and others above a reduction of the demand sees the cell voltage restoring. Cold temperatures seem to be a major factor. Continuous logging with LeafSpy will highlight the issue and show probably only a few cells sagging under load over time.

 

[dwl]

Having the same issue on my 2020 SV (40kw) with 50k miles. It happens when the battery is around or below 50% charge, I am driving at 50+ mph, and especially when on my daily commute 400 ft elevation incline.

I recorded it on my phone and brought the car to the dealer. Fluctuation was about 15% over the course of 2-3 miles. Largely "regained" on the downhill. Nissan kept my car for a week, trying to replicate my recording, but could not replicate it enough for them to authorize a fix. No codes are being thrown.

Now a month later I'm getting 30% fluctuations. I'll record again and bring it in again.

My dealer said they have seen a few of these, and to just bring it back when it gets worse. I'll bring it in again in the near future. In my case, I think the big incline, and thus strain on the battery, is what triggers it. So far they have been supportive and did not charge for checking the car. They predicted they would eventually have to fix it. I have plenty of warranty left and they told me not to worry about it. This is our 2nd Leaf. Drove 90K on our 2013 with out any issues. Been saving a fortune on fuel for a decade!

Does anyone know:

The fluctuations shown on the gauge - how do they relate to the actual state of the battery? Since the % charge is "regained" on the downhill, I ASSumee it was never gone to begin with? I am hoping not to get stranded before I have a chance to bring it in again.

Pete

As mentioned above, the charge is still in the cells but a few of them cannot deliver the required power without the voltage dropping significantly. If the load is sustained the voltage drop will continue and when below cutoff voltage the car will shutdown. The SoC % reading is signalling the problem. The experience we have had in New Zealand winter with 40kWh Leafs is a new highway that has a long climb requiring about 50-60 kW (or more with head wind) for about 3 minutes which is enough to highlight the issue on several cars. These are often ex Japan without warranty. The cars can have zero issues when warmer. If your dealer has seen several with this issue then your area might have similar load conditions and hopefully Nissan will honour warranty.

 

[Oostenrijker]

If your dealer has seen several with this issue then your area might have similar load conditions and hopefully Nissan will honour warranty.

I have exactly the same issue, as described by OP: my Nissan Leaf was sold to me, with an mileage of 171.000km. The ad stated, that the car has always been fully dealer maintained. But I think, Nissan doesn't do thoroughly battery checks?

These are done, when the car are idling: almost all of us, only experience these use when the car is under heavy load. German Autobahn, or a big climb. So their is definitely, one or more faulty cells in the battery pack.

However, Nissan and especially the dealerships who sell them used: aren't that snappy, on acknowledging these issues. They basically say, it's normal for the amount of mileage, and even state that they think it would be the case with other high mileage as well.

I already challenged this: told them, when you wanna trade my car to another high mileage. That's fine? Just let me read out the car with Leafspy, and I could make a good assessment.

But it's nuts, they are saying these issues are normal. As everyone knows they aren't.

 

[dwl]

I have exactly the same issue, as described by OP: my Nissan Leaf was sold to me, with an mileage of 171.000km. The ad stated, that the car has always been fully dealer maintained. But I think, Nissan doesn't do thoroughly battery checks?

These are done, when the car are idling: almost all of us, only experience these use when the car is under heavy load. German Autobahn, or a big climb. So their is definitely, one or more faulty cells in the battery pack.

However, Nissan and especially the dealerships who sell them used: aren't that snappy, on acknowledging these issues. They basically say, it's normal for the amount of mileage, and even state that they think it would be the case with other high mileage as well.

I already challenged this: told them, when you wanna trade my car to another high mileage. That's fine? Just let me read out the car with Leafspy, and I could make a good assessment.

But it's nuts, they are saying these issues are normal. As everyone knows they aren't.

In terms of the warranty wording it may be difficult to challenge as it is a performance issue rather than just capacity. In the case here in New Zealand a new motorway is the main state highway heading into the capital city with a long steep climb and 100kph speed limit. With our consumer guarantee laws the car needs to be fit for purpose and being able to sustain the speed limit over this highway is a reasonable expectation so second hand car dealers have offered replacement car options (same model just healthier battery).

It was colder winter weather that highlighted the issue and several different cars exhibited the same symptoms. Most 40kWh Leafs here are second hand imports from Japan with maybe only 5% sold new by Nissan and I haven’t yet heard of new car warranty claims but those cars are not old. There are indications that if the cars have experienced heat in Japan the degradation on some cells is more obvious.

I don’t think this problem is going to go away and I am following with interest.

 

[hornstudio]

Nissan needs to talk to his supplier and tell him they gave 8 years or 160.000km warranty on the drive battery.

Mitsubishi exchanges whole drive batteries on warranty since long time when weak/dead cells occure, 2nd hand to 2nd hand. Dealers buy them on deposit (+-11.000€), distributor ships the whole pack back to Japan to rework. Dealers only exchange the batteries like tires, then they get their deposit back.

In the beginning Mitsubishi exchanged 2nd hand against new batteries, but this is over.

 

[Oostenrijker]

In terms of the warranty wording it may be difficult to challenge as it is a performance issue rather than just capacity. In the case here in New Zealand a new motorway is the main state highway heading into the capital city with a long steep climb and 100kph speed limit. With our consumer guarantee laws the car needs to be fit for purpose and being able to sustain the speed limit over this highway is a reasonable expectation so second hand car dealers have offered replacement car options (same model just healthier battery).

It was colder winter weather that highlighted the issue and several different cars exhibited the same symptoms. Most 40kWh Leafs here are second hand imports from Japan with maybe only 5% sold new by Nissan and I haven’t yet heard of new car warranty claims but those cars are not old. There are indications that if the cars have experienced heat in Japan the degradation on some cells is more obvious.

I don’t think this problem is going to go away and I am following with interest.

I think you might be right: it's an performance issue, but if it gets so bad that the car throws an DTC and leaves you stranded? Then it's definitely an battery issue.



Look here is what's happening with my Leaf: once I push the pedal in one go, without ECO mode. Then at a outside temperature of 10 degree Celsius, this happens.

It's the same cel, which everytime is the weakest: surprisingly not my weak cells on the left, of which I expected wss causing the issue. For the sake of my mental health, I now have told the Nissan dealership: maybe I was panicking? And perhaps the car magazine program I took part of, tends to make things more dramatic.



Here you got my car: the actually video isn't out yet. But either way it ain't going do Nissan good.... only 82% SoH whereas an Hyundai Ioniq scored 91% SoH with a similar mileage. So that doesn't look very good for the Leaf.

And then the verdict of the expert, was quite harse as well: he said, a repair is coming in the near future. Well that's when I escalated things. But now I realise, as long there is no DTC and I'm not left stranded with the car? Then there isn't much I can do!

So I will try one more time when it gets cold, around freezing temperature. If my Leaf then still doesn't throw a DTC, then I guess I'm safe to assume I could still drive some years with minor battery issues in the winter. But if it throws the DTC? And the Nissan dealership, is still not offering a solution? Then I'm taking it to the dispute commission.

Basically you want it throw a DTC: because you can show as many Leafspy screenshots you want. Nissan doesn't accept it, and doesn't even look at it. And you know what's the worse thing? They also refuse, to diagnostic while driving the car!

Nissan could replicate the issue, with their own tools? Or do they really not have the ability, to diagnose battery problems while driving the car? As what they are doing now, is only measuring the battery pack while it's in for service. So it ain't driving....

 

[dwl]

…snip… Nissan could replicate the issue, with their own tools? Or do they really not have the ability, to diagnose battery problems while driving the car? As what they are doing now, is only measuring the battery pack while it's in for service. So it ain't driving....

Your Hx of 65% is low and there is debate about the importance of this metric. I assume that the graph is under heavy load (a landscape view of LeafSpy would show current) as the voltage is very low for over 50% SoC. For my 2018 I did this load test (when warmer) and the cell voltages are a lot higher. My SoH was about 85% and Hx about 86% at this time.
The power draw of about 60kW is enough to sustain highway speed up this incline with a tailwind. In this example it is sagging about 200mV for that 60kW load. The same battery when cold with a headwind (maybe 65-70kW power needed) went into cell voltage deficit where voltage could not be sustained and SoC on the dash crashed from about 25% down to 10% and then close to 0% for the same time on the graph above of the climb (first 2.5 minutes).

I suspect that the Hx metric may be a guide but I doubt it will adequately reflect how bad individual cells ave become. Any thoughts from the knowledgable people on this forum would be welcomed.

 

[hornstudio]

I may suggest to do annual service check at Nissan dealers to have full "mobility warranty for next 12 months" and everytime you get into trouble call the assistance (sticker on windscreen) to bring the truck and drive you and your LEAF to next charging station. That costs Nissan much more money than a weak cell fix. Good idea?

 

[Oostenrijker]

Your Hx of 65% is low and there is debate about the importance of this metric. I assume that the graph is under heavy load (a landscape view of LeafSpy would show current) as the voltage is very low for over 50% SoC. For my 2018 I did this load test (when warmer) and the cell voltages are a lot higher. My SoH was about 85% and Hx about 86% at this time.

Yes I did the test under heavy load: I also noticed the min voltage got very low at 2.698 and this was only at 50% SoC: I'm waiting until it gets colder, next week around this time temperatures are suppose to be around 0 degree celsius or even colder. The plan is to not charge the battery full, because I need the battery to be between 20% and 30% because my goal is to trigger that DTC. My dealership who sold me the car, basically doesnt even look at the Leafspy data I would send. Even though its factual information.



So my assumption is, when it already looks so bad at only 10 degree Celsius. Than I imanage if I do it again at 0 degree celsius, and with an cold battery. Which means I should refrain from charging to much, because in one week the temperatures will drop so much. That I'm going have perfect conditions, because if the battery is warm it isn't likely to happen. Actually I noticed most people report battery issues with the battery pack, during winter.



Here I went and see how far I could drive the battery empty: at 12.5% I had Turtle Mode, but no EV Warning. I saw the EV Warning light go on once, after trying to use a Shell fast charger that wasn't working. And after that I drove to a public charger, plugged in my car. Saw that it started charging, but it didnt charge at all. Still not sure if it actually was the car causing this? Because when I tried the other socket of the public charger, it all of a sudden worked.

I see my Hx was higher back then: it was an older Leafspy Pro version, thats why there is the odo shows ?? in the current version I use its fixed. What I also see, the minimum voltage didn't go as low as it did in the recent video I made with Leafspy.