40kwh replacement battery degradation expectations?

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cdherman

Well-known member
Joined
Apr 8, 2012
Messages
209
Location
Kansas City, Missouri
I got a replacement 40kwh battery right at 24 months ago for my 2016, 15k miles later. 2 warm Summers. Zero QC. As we know, much of Leafspy gets disrupted by a replacement battery, especially of a different size (original was 30kwh)

I didn't plug my Leafspy in for at least 18 months, but a friend and fellow Leaf owner wanted to check his battery, and I plugged into my car to make sure all was still working with my phone/app/OBDII etc.

Showing 92.3% battery health. Seems about to be expected with normal initial degradation to me. Would more knowledgeable people agree? You think that aspect of Leafspy is still accurate?
 
I admittedly don't use LeafSpy, but I don't understand why it would be "disrupted" by a replacement battery. It's not part of your car, it's an app that you can use to monitor your car.

Perhaps you would want to reset it if it keeps a history of the metrics it is monitoring, but I would assume that's pretty easy to do.

To answer your question, yes I would assume that the numbers reported for your car are accurate.
 
I admittedly don't use LeafSpy, but I don't understand why it would be "disrupted" by a replacement battery. It's not part of your car, it's an app that you can use to monitor your car.

Perhaps you would want to reset it if it keeps a history of the metrics it is monitoring, but I would assume that's pretty easy to do.

To answer your question, yes I would assume that the numbers reported for your car are accurate.
When the battery (HV) get replaced, the BMS is changed also and the memory of the old battery is gone.
So your history is "disrupted" but that is all.
 
When the battery (HV) get replaced, the BMS is changed also and the memory of the old battery is gone.
So your history is "disrupted" but that is all.
I think that varies. My vehicle shows all the old charging data, number of L2, QC etc from the old battery. And the GIDs are all messed up. Suspect that the technician did not know how to reset the BMS correctly. That is what I mean by "LeafSpy being messed up" It does not show all the data accurately as it did before. I *hope* that the SOH is however still accurate.
 
Sounds like it would be worth asking this question to the business/dealership that did your battery swap.
 
Well, I am going to revive this thread and perhaps someone will give opinion(s)

I am at 3 years on the replacement 40kwh pack. 3 hot KC Summers, though the car is garaged and I never QC.

A year ago, I was down to 92% SOH, now at 3 years, I am at 88.5% SOH at about 34,000 miles on the battery.

Should I be worried?

I attached a screen shot from Leafspy. This illustrates the problem I noted last year -- the QC and L1 charging stats are wrong -- they are from the old battery + L1 charges from the new one. But at 50% SOC, the batteries dont seem to have a great deal of variance. But I don't know much about this.
 

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As much as I respect cornbinder's input, I still feel that the continuing 4 % degredation from year 2 to 3 of battery use is worrisome? Isn't the battery degredation curve supposed to flatten? Lets see -- I dropped 8% in the first 2 years, now 4% more in the third. Does not feel like flattening......
 
Degradation is more if is charged overnight at 100% nearly daily then DC charging.
Every year will lose 1-3% without considering charging behavior
 
Very true but I talk in his case or for thous ( and ar so many ) that nearly never used a DC charger.

In my case , a DC overheating charges nealy 100%, crushed 2 cells ( under driver seat pack ) , but they crushed after some days over that trip.
 
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Well, I hope you all are right. A friend with a 2018 40kwh Leaf is having trouble with sudden loss of range. He did not have Leaf Spy and the OBDII dongle, so came over and we drove his vehicle, observing the sudden loss events, especially with full acceleration in the cold. Its pretty clear, he's got some bad cells. But only 1 bar capacity loss. He's headed to Nissan next week. He has screen shots and videos of the LeafSpy showing massive increase in the pack voltage variance. And sudden range loss.

Today I drove my Leaf down to 10% SOC in the cold (19f) and was able to accelerate normally, maintain 65 mph. No issues. I loaned him my OBDII reader, so could not see if there were individual cells that were mis-behaving. No sudden range loss. I was on a 40 +/- mile set of errands, left with 59% charge, drove mostly around 60-65, but some residential at 30 or so. Returned home 10%. Was running defrost40% of the time, heat with recirculate the rest. Windy too. I think indeed, I am OK. Dang -- wanted to shop for an Ioniq 6!!!

Ok, back to the game (KC versus Houston, playoff, GO CHIEFS)
 
What I found is that if you run too many things at once, the battery loses range quickly almost to the point of turtling. In this cold weather, it is taking longer to charge my 2020 Nissan Leaf. The dealer turned off my charging timers because my car was not fully charged--despite being plugged into my new appliance outlet (I had to install because 16 hrs of trickle charge was impractical). Next the dealer turned off my auto lights, so I've been manually turning them on at night. I also found that the climate control reduces my range mileage by 10--if I turn it on to defrost my windows, my range drops from 118 to 108--so I only turn it on when my windshield fogs, then quickly back off so my miles return back to 118. I've even stopped using my external CD player, because that also was draining my battery. So I pick & choose which things will be turned on, so I will not lose too much mileage--Driving above 70 miles also quickly drains my milage range. I can drop from 125 mile range to 80 mile range fairly quickly if I'm on the fast lane on the freeway. It dropped almost to 30 mile range & I was tempted to head back home, until I pulled off the freeway & my mileage shot back up to 50 mile range. I trickled charged my car at work and it was back at 80 mile range--enough to drive home at night using only the headlights--all accessories was off.
I just didn't want to repeat my car turtling & shutting down to strand me 15 miles from my house. This occurred w/in my first 6 months of ownership of the test driving car from the dealer which I bought in August 2022--it broke down Jan 2023. By the time the tow truck driver showed up, the 12 volt battery had died & I couldn't open the charging hatch once AAA towed me to the Chademo chargers at Walmart in San Leandro. It was raining, it was night time, it was a 2 hr wait for the tow-truck driver & my car had to be pushed to a safe spot to park, before it completely locked down. This was $$ out of pocket because the first tow was beyond 5 miles. & the 2nd tow to my home was completely out of pocket because AAA only paid for one 5 mile trip. Then it was another out of pocket expense to have it towed to the dealership using the Nissan Towing Service supplied by the dealership when I first bought the car. The Fremont dealership is also beyond the 5 mile tow limit. Turns out, part of my computer had to be replaced since they could not upload the complete history when they diagnosed my car.
When my car lit all my dashlights, I had my car towed to the dealership before my next tire rotation appt. They asked why my car was being towed there, I said Xmas. So when they attempted to start my car, all the dash lights came on. Turns out I had bad cells & my battery needed replacing--good thing I extended my warranty so that the battery was replaced for free, but I was w/o a car for the entire month of August 2024. So when my car was acting up this winter, I was afraid of another turtle incident. Of course, the tech could not recreate the conditions when my car almost turtling in San Leandro on my drive home from work. It turtled but I could still drive 60-80 mph on the way home. That's when I read on the forum about the battery discharging more rapidly during cold winter months. Hence the practice of picking & choosing what to turn on to minimize any affect on my mileage range.
 
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