Patience or Push the Issue (New Cells/New Pack)?

[mn4az]

Love my Leaf but the degradation leading to the Limited Motor Power (ie turtle mode) with the SOC% bouncing all over the place is a bit unnerving when it's below freezing.

Today's drive was 37 miles in 10F temperatures, and I left the garage fully charged, battery pack balanced and car pre-heated. With some creative driving (trying avoiding hills at high spped, mostly avoiding speeds of 55MPH+, cabin temp at 60F, etc) I was able to get home with .9kWh in the pack. Once safely in my garage LeafSpy showed three weak cells (#30, #42 and #46). FWIW #42 and #46 showed as weak last week with a SOC of 36%.

I know my Leaf is very likely to hit the battery degradation warranty this spring/summer (which I am SO looking forward to), but I'm half tempted to try and force a DTC event (like the one documented here: https://mynissanleaf.com/viewtopic.php?p=627932#p627932) that shuts the car down, have it towed to a Nissan dealership (I have AAA so no worries about a tow charge) and force Nissan's hand to either fix the cells or replace the pack. The only thing keeping me from doing this "experiment" (basically go to a road that is 55MPH+ with a significant incline) is that if cells are replaced, I fear it would risk the entire battery being replaced under the battery degradation warranty.

Some pictures I've taken over the last couple of weeks: https://1drv.ms/u/s!AmMHBcyzLWAx8K89Z3ZoHYghn5xg-Q

Looking for thoughts from this community: Would you have patience for the rest of the winter and stay the course for the battery degradation warranty (ie new pack) or push the issue for a new cell/pack now?

 

[Lothsahn]

Make sure you already have the 30kWh firmware update applied. That can improve battery performance and restore bars... Or do nothing. But it is needed to get a warranty claim.

I doubt Nissan would try a cell level repair on a pack like that if it did throw codes. You'd probably just get put in the queue for a new pack... Which is currently something like 6 months.

Just my opinion, but I'd you could trigger a cell failure code that's probably a reasonable plan. Or loan it to a friend in Phoenix for 4 months!

 

[mn4az]

The LBC has been reprogrammed so no worries there and very aware of the long wait time on a replacement pack.

My parents live in Phoenix. While that's a fun option to think about I'm very confident that, based on the data I've been collecting every month that the trends are such that the 4th bar will drop this summer.

My kid is home from college and driving the car to/from work (about 10 miles round trip) until mid-January. Maybe it'll just magically pop a DTC for her on the way home one day (I've given her the heads up on what to expect if it does).

 

[Learjet]

With my 2019 SL+, I brought the issue up to a Nissan dealer during the annual check early in the year, but they said it would be easier to wait for a code from the weak cell... which didn't happen until it got to 500 mv less than the other cells. In the shop now wait on a battery module.

 

[mn4az]

With my 2019 SL+, I brought the issue up to a Nissan dealer during the annual check early in the year, but they said it would be easier to wait for a code from the weak cell... which didn't happen until it got to 500 mv less than the other cells. In the shop now wait on a battery module.

Helpful data point. Thank you.

I haven't been paying close attention to the max difference of voltage across the cells but yesterday LeafSpy's Voltage Histogram page showed a max difference of 245mv. Seems like your cell was really bad.

I hope you get your new module faster than those who are waiting for new packs.

 

[SageBrush]

Your 37 mile drive consumed about 500 Wh/mile. I'm surprised it was that high not using cabin heating. Perhaps defrost, or perhaps tyres ?

As others have said, I doubt you will be able to force a DTC for now.

 

[mn4az]

Your 37 mile drive consumed about 500 Wh/mile. I'm surprised it was that high not using cabin heating. Perhaps defrost, or perhaps tyres ?

As others have said, I doubt you will be able to force a DTC for now.

Cabin heat was at 60F. No defrost. Tire pressure at 38 PSI.

 

[Stanton]

Looking for thoughts from this community: Would you have patience for the rest of the winter and stay the course for the battery degradation warranty (ie new pack) or push the issue for a new cell/pack now?

Here's my advice based on the fact that I just went through a cell/module replacement (not under warranty) in my 40 kWh pack.
I would wait to trigger the 8CB replacement pack warranty. You will get a 40 kWh pack (much better lifespan than the 30 kWh pack) and there are simply no "replacement" modules available in Nissan's system (I bought mine on eBay); that's not to say you will get a new pack quickly either, but probably faster than a cell replacement--not to mention your weak cells span 2 different modules (I only had to source 1 module). I really feel for folks that basically have to go through what I just went through, and I had the knowledge/resources to do this myself...so good luck with whatever you decide (because the uncertain/unreliable range sucks).

 

[SageBrush]

Your 37 mile drive consumed about 500 Wh/mile. I'm surprised it was that high not using cabin heating. Perhaps defrost, or perhaps tyres ?

As others have said, I doubt you will be able to force a DTC for now.

Cabin heat was at 60F. No defrost. Tire pressure at 38 PSI.

Then see if LeafSpy can help you identify the cause(s). using the power categories A much more reasonable Wh/mile will help you wait out the car until warranty kicks in.

E.g., you LeafSpy screenshots show ~ 3 kW power for A/C. That is not enough to explain 500 Wh/mile unless your average speed was really low, but I mention it for the approach I am suggesting.

 

[mn4az]

Looking for thoughts from this community: Would you have patience for the rest of the winter and stay the course for the battery degradation warranty (ie new pack) or push the issue for a new cell/pack now?

Here's my advice based on the fact that I just went through a cell/module replacement (not under warranty) in my 40 kWh pack.
I would wait to trigger the 8CB replacement pack warranty. You will get a 40 kWh pack (much better lifespan than the 30 kWh pack) and there are simply no "replacement" modules available in Nissan's system (I bought mine on eBay); that's not to say you will get a new pack quickly either, but probably faster than a cell replacement--not to mention your weak cells span 2 different modules (I only had to source 1 module). I really feel for folks that basically have to go through what I just went through, and I had the knowledge/resources to do this myself...so good luck with whatever you decide (because the uncertain/unreliable range sucks).

Appreciate the input. The uncertainty/unreliable range does suck, but it's the health hazard of being stuck on the side of the road when it's -10F (or colder) that I'm most concerned about.

Given there's no replacement modules, it makes me wonder if, like the individual in CO (linked in my OP) if they'd just replace the whole back if a DTC event happened.

 

[mn4az]

Your 37 mile drive consumed about 500 Wh/mile. I'm surprised it was that high not using cabin heating. Perhaps defrost, or perhaps tyres ?

As others have said, I doubt you will be able to force a DTC for now.

Cabin heat was at 60F. No defrost. Tire pressure at 38 PSI.

Then see if LeafSpy can help you identify the cause(s). using the power categories A much more reasonable Wh/mile will help you wait out the car until warranty kicks in.

E.g., you LeafSpy screenshots show ~ 3 kW power for A/C. That is not enough to explain 500 Wh/mile unless your average speed was really low, but I mention it for the approach I am suggesting.

My speculation is that the BMS is "misrepresenting" what on the dashboard to protect the pack. LeafSpy showed .9kWh in the pack but the SOC showed 29.7%. The dashboard in the car was aligned to the .9 kWh not the SOC which, in my experience, is abnormal.

 

[Lothsahn]

Looking for thoughts from this community: Would you have patience for the rest of the winter and stay the course for the battery degradation warranty (ie new pack) or push the issue for a new cell/pack now?

Here's my advice based on the fact that I just went through a cell/module replacement (not under warranty) in my 40 kWh pack.
I would wait to trigger the 8CB replacement pack warranty. You will get a 40 kWh pack (much better lifespan than the 30 kWh pack) and there are simply no "replacement" modules available in Nissan's system (I bought mine on eBay); that's not to say you will get a new pack quickly either, but probably faster than a cell replacement--not to mention your weak cells span 2 different modules (I only had to source 1 module). I really feel for folks that basically have to go through what I just went through, and I had the knowledge/resources to do this myself...so good luck with whatever you decide (because the uncertain/unreliable range sucks).

Appreciate the input. The uncertainty/unreliable range does suck, but it's the health hazard of being stuck on the side of the road when it's -10F (or colder) that I'm most concerned about.

Given there's no replacement modules, it makes me wonder if, like the individual in CO (linked in my OP) if they'd just replace the whole back if a DTC event happened.

I suspect with your pack health and 30kWh that if a DTC triggered, you'd get a new pack.

You sure you don't have a stuck brake caliper or something? That could lower the range. Should be easy to check with a laser thermometer after driving for a while. Just brake slowly (so you don't engage the brakes much) and check temps.

 

[mn4az]

Here's my advice based on the fact that I just went through a cell/module replacement (not under warranty) in my 40 kWh pack.
I would wait to trigger the 8CB replacement pack warranty. You will get a 40 kWh pack (much better lifespan than the 30 kWh pack) and there are simply no "replacement" modules available in Nissan's system (I bought mine on eBay); that's not to say you will get a new pack quickly either, but probably faster than a cell replacement--not to mention your weak cells span 2 different modules (I only had to source 1 module). I really feel for folks that basically have to go through what I just went through, and I had the knowledge/resources to do this myself...so good luck with whatever you decide (because the uncertain/unreliable range sucks).

Appreciate the input. The uncertainty/unreliable range does suck, but it's the health hazard of being stuck on the side of the road when it's -10F (or colder) that I'm most concerned about.

Given there's no replacement modules, it makes me wonder if, like the individual in CO (linked in my OP) if they'd just replace the whole back if a DTC event happened.

I suspect with your pack health and 30kWh that if a DTC triggered, you'd get a new pack.

You sure you don't have a stuck brake caliper or something? That could lower the range. Should be easy to check with a laser thermometer after driving for a while. Just brake slowly (so you don't engage the brakes much) and check temps.

Just had the rear pads/drums replaced this summer. Hopefully it wouldn't be that, but the laser thermometer is a good idea. Thanks.

 

[user 24513]

Wet finger on the brake disc works well also..... Quick touch- if it steams you got problems!

 

[SageBrush]

LeafSpy showed .9kWh in the pack but the SOC showed 29.7%.

Photos of that would be helpful, including a photo of the cell voltage histogram at the same time.
If not this time, maybe next time.

 

[LeftieBiker]

Wet finger on the brake disc works well also..... Quick touch- if it steams you got problems!

As someone who once melted the friction ridges (fingerprint) on one finger doing that, I'd like to suggest using a wet, inanimate object, instead.

 

[user 24513]

Ah yes that is probably smarter..... but are your fingerprints now untraceable? might be some advantage there!

 

[LeftieBiker]

That one finger would have been pretty hard to search, anyway. They do grow back, though, as countless mobsters learned the hard way. I spent my working career, BTW, working with fingerprints and arrest cards.

 

[mn4az]

LeafSpy showed .9kWh in the pack but the SOC showed 29.7%.

Photos of that would be helpful, including a photo of the cell voltage histogram at the same time.
If not this time, maybe next time.

The original post has a URL to a OneDrive folder with those pictures. Interested in what you see.

 

[SageBrush]

The original post has a URL to a OneDrive folder with those pictures. Interested in what you see.

I looked them over, and compared to my screenshots.
My screenshots show the GID percentage 5 - 10% lower than the SoC
Your screenshot shows a GID percentage that about matches the kWh remaining while the SoC percentage is wildly discrepant.

I do not know for sure how to explain the discrepancy. One guess could be that the GiD is calculated as if all the cells were the same voltage as the lowest cell, while the SoC uses the average (or cumulative) voltage. I found one screenshot from my car of a SoC of 36% showing cumulative voltage as 370V. The idea that you are looking at average Vs lowest cell voltage derived values would be consistent with finding that the SoC/GID percentage delta increases as the pack is depleted. This would be true because the weakest cell has more of an effect the more the pack is depleted.

If you look at a graph of cell voltage Vs capacity remaining for Li-x cells you will note that the voltage drops steadily but gradually from ~ 95% SoC to ~15% SoC, and then falls off a cliff at around 330V (about 3.4V per cell). When you got home your weak cell voltage was at 3.24V -- way into the cliff, so LeafSpy values that meant 'about to enter turtle' are correct because the lowest cell voltage sets the turtle bar. Your total pack voltage was 335.14V which may have been just at the start of the cliff.

Conclusions
The weakest cell in your pack is costing you the bottom ~ 20% of usable capacity
Believe the GID percentage
Keep looking for possible increased frictions or power drains given the Wh/mile

Addendum
Let's calculate Wh/mile again, using what is known and conjectured:
A new 30 kWh pack has about 28 kWh usable
Your SOH of 0.68 implies a usable of 19 kWh
The weak cell cuts off the bottom 20%, so 15.2 kWh is usable
You arrived home with 1.9 kWh remaining, so 13.3 kWh was used to travel 37 miles
13,300Wh / 37 miles = 360 Wh per mile.

Hmmm. That is more believable, particularly if you were sitting idle at stoplights since you were still drawing the better part of 3 kW for cabin conditioning. If you can, try low speed highway driving for your commute.