Individual battery module replacement vs whole pack tracking

[EV4Taos]

Hi

I would like to use this thread to report defect or capacity warranty work done at Nissan dealerships. Not just direct experiences, but any info from people either virtual (internet/forums) or not (in person).

Specifically it would be nice to see when and if Nissan decides to start replacing modules instead of whole packs, since the battery warranty does give Nissan the right to only replace modules.

Tracking this information with help all of us make an informed decision on buying our first Leaf, our next leaf, or when to sell it. Model year, date of replacement, capacity before and after, and what was replaced would be most helpful.

 

[Stoaty]

Individual module replacements are rare (there have only been a couple of reports), whole pack replacements are common for those who live in climates with average or above average temperatures. In most cases there isn't any point replacing individual modules because the entire pack has been "cooked" and undergone fairly uniform degradation.

 

[EV4Taos]

Individual module replacements are rare (there have only been a couple of reports), whole pack replacements are common for those who live in climates with average or above average temperatures. In most cases there isn't any point replacing individual modules because the entire pack has been "cooked" and undergone fairly uniform degradation.

Were the module replacements reported on this forum? If so do you have the links? Is a couple 2 or 3?
Would love to know why the dealership decided to go with a module replacement and which dealership did the work.

Just trying to get as much info as possible.

 

[Stoaty]

Were the module replacements reported on this forum? If so do you have the links? Is a couple 2 or 3?
Would love to know why the dealership decided to go with a module replacement and which dealership did the work.

Don't know the number, I think a couple were reported somewhere on the forum. The dealer went with the module replacement because the problem was a bad module rather than a bad pack. It isn't up to the dealer, Nissan decides what needs to be done if there is a warranty issue.

--If there is a bad module, a pack replacement isn't needed.
--If the pack is bad (degraded too much), a module replacement wouldn't help.

 

[EV4Taos]

Thank you that is helpful. If anybody hears of more module replacements please post here. I am a little worried Nissan might replace a couple modules as a cheaper way to get the capacity back to say 75%, just before the 60k warranty expires. It would be good if we keep tracking this to catch any change in Nissan's policy early. There has been a big change in leadership recently so you never know.

 

[TimLee]

The few module replacements I have read about on MNL were mostly where a problem was detected. I only recall seeing 2 or 3 posts.

Unlikely they would start changing just a few modules to get through the 5 year / 60,000 mile capacity warranty period.

But the service manual does have a Cell Voltage Loss Inspection (CVLI) test.
Has to be run at very low cell pair voltages below Low Battery Warning.
And it indicates basis for doing the test is if customer has complaint of vehicle range.

But the test is a bit imprecise.
It says replace modules for cells that fail the criteria.
But is not explicit on whether you do that just once the voltage is below the threshold, or whether you could keep checking voltage on down to Turtle or to the point LEAF has shut itself down completely.

LEAF Spy Pro includes CVLI test.
I have done it once.
At the point cell voltage was low enough to do CVLI, I had 2 or 3 cell pairs that weren't passing.
But as voltage kept dropping, there were eight that weren't passing when I stopped testing at Very Low Battery Warning.

But note that CVLI is not associated with capacity warranty.
Failing cells should be covered on the original battery defect warranty, 8 years / 100,000 miles as I recall.

8 out of 96 cell pairs seems pretty high for 39 months old, ~22,000 miles (have lost one capacity bar, close on second capacity bar, but I have not had the P3227 software change that adjusts capacity measurement and some other things).
But depending on how the bad cell pairs are distributed, it could be 4 to 8 modules out of 48.
I think as time goes by it is pretty likely that Nissan will be required to do some module and/or complete battery replacements under the original defects warranty.
But just doing the CVLI failing modules alone would likely not be a good long term choice for overall battery capacity or longevity.

 

[EV4Taos]

Thanks for your thoughts. Its hard to say what Nissan would trust a dealership tech with. The test is probably only useful for replacing modules. Seems like there would be an easier way to see if the pack needs swapping. The question is could a handful of modules cause the entire pack to drop to 69%? This is the only situation I can think of were Nissan would not swap the pack, but just replace the modules.

 

[Stoaty]

The question is could a handful of modules cause the entire pack to drop to 69%?

I believe a single faulty module could do that. The pack is only as strong as the weakest module.

 

[EV4Taos]

The question is could a handful of modules cause the entire pack to drop to 69%?

I believe a single faulty module could do that. The pack is only as strong as the weakest module.

Don't you think that would through an error code for a cell to be so different from the avg? Perhaps even a fire risk?

 

[johnrhansen]

I dont see how it could make sense to change just a module or 2 in a degraded battery. All the cells are in series! So one new cell mixed with a lot of old ones could cause some unbalanced voltages as the battery charges and discharges. I've never seen it done before.

 

[Stoaty]

Don't you think that would through an error code for a cell to be so different from the avg? Perhaps even a fire risk?

If a module is functioning at a low enough level, the Leaf notifies Nissan and they call the owner to have the module replaced (have seen one instance of this reported, probably has to be pretty bad for this to happen). Fire risk, no. The Leaf will shut itself off before things get that far. No reported fires of Leaf battery packs.

 

[EV4Taos]

Don't you think that would through an error code for a cell to be so different from the avg? Perhaps even a fire risk?

If a module is functioning at a low enough level, the Leaf notifies Nissan and they call the owner to have the module replaced (have seen one instance of this reported, probably has to be pretty bad for this to happen). Fire risk, no. The Leaf will shut itself off before things get that far. No reported fires of Leaf battery packs.

Do you think you could find where this was reported? Thanks for the thoughtful discussion.

 

[johnrhansen]

How about we s owners the only time my car ever communicates with nissan is during the annual battery vheck as far as I know. What should we be watching for?.

 

[Stoaty]

Do you think you could find where this was reported? Thanks for the thoughtful discussion.

No, but you can search the forum and probably can find it with enough persistence.

 

[Stoaty]

How about we s owners the only time my car ever communicates with nissan is during the annual battery vheck as far as I know. What should we be watching for?

Nothing. You are more likely to be struck by lightning. Don't worry about it.