Do I have dead cell/module?

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Thekuai

Well-known member
Joined
Oct 12, 2018
Messages
45


These screenshots was taking in leafspy pro 12 hours after a full charge. I have 12/12 bars and 95 mile indicated range car is a 2015 sv with 17k miles




 
I just got the car last week and I haven't taken it down to low. I assumed 97% soc was as good as full?
 
Thekuai said:
I just got the car last week and I haven't taken it down to low. I assumed 97% soc was as good as full?
At least your on the 50 mv scale, a lot have reported worse.
I agree, take it down to LBW and to VLBW if the differential is still close to the same them report the lowest cell voltage at both levels here.
 
Thekuai said:
I just got the car last week and I haven't taken it down to low. I assumed 97% soc was as good as full?

I looked at your cell-pair voltages and thought your battery was at about 80% SOC. I see now that it reports 97% so there is something wrong with your car or with LEAF Spy. Your screenshot shows the overall pack voltage as 395.86 which is really high, but average cell-pair voltage as only 3.911 so there is something wrong with the data. 3.911 X 96 = 375.456 (which would be about right for 70% to 80% SOC). Cell-pair voltage at full charge should be about 4.1 or a little higher. 395.86 / 96 = 4.1235 volts per cell average (which is higher than maximum cell voltage that the lithium battery controller normally allows).
 
Definitely not looking promising. Post a voltage pix at 75% and 50% SOC. Try to post right after driving.

Be mindful of going to a lower SOC as Turtle is voltage controlled and can be triggered by a single low cell which means you could go from 40% SOC to dead within a mile or two.
 
Could it be possible that my obd2 Y splitter cable and ConEd smartcharge device be causing intereference?
 
Thekuai said:
Could it be possible that my obd2 Y splitter cable and ConEd smartcharge device be causing intereference?

The Y splitter cable should not cause an issue because I use one to keep my original GID meter and the Bluetooth adapter for LEAF Spy without incident. I am not familiar with the ConEd smart charge device, but iit could be a problem if it checks SOC and controls/monitors charging.
 


I unplugged the coned device and yes it does collect SOC info.

Are these numbers more accurate?
 
I've never personally seen imbalance as large as 45 mV when nearly full (OP's first post) nor have seen 49 mV imbalance at the type when SoC is at ~42% either. At rest (above LBW), even w/the heater on and headlights on, I don't think I've seen imbalance beyond 30 mV.

Unfortunately, I don't off the top of my head know definitive answers about the CVLI test, but Googling for site:mynissanleaf.com cvli test might help.

http://www.mynissanleaf.com/viewtopic.php?p=457982#p457982 is an example of pretty big imbalance. JeremyW didn't succeed in getting a module replaced but BiggieJohn did. However, sometime after module replacement, he hit 8 bars and the whole pack was replaced.
 
You're right, Cwerdna. With those colors it's especially hard to see that one very low cell, but when I looked again carefully it's right there, looking like a weak cell in an otherwise ok pack. I wonder how one would try to ensure that the CVLI test came back with the biggest imbalance. My guess would be never fully charging, or getting below 20%...
 
I've posted the cvli test here before. IIRC it is tested at VLBW

Cell #88 is weak.
Whether it meets the bar of the cvli test to invoke the defective battery warranty remains to be determined
 
:idea:
LeftieBiker said:
THAT looks much more like a typical Leaf pack in need of normal balancing (by charging until all charging lights shut off at 100% indicated charge.

I'm new to leaf spy, why are some lines red and some blue? And why is module #87 or 88 still very low? So the leaf self balances at 100% SOC? I've read that bottom balancing (running the leaf down to almost 0) is unnecessary for the leaf as it has an advanced BMS. I heard it's only for people who build vehicles with salvaged batteries without BMS.
 
Thekuai said:


I unplugged the coned device and yes it does collect SOC info.

Are these numbers more accurate?

Is there a reason you chose to do this with a black background?

how long since drive did you take this?

Try again with white background. This time do two with resting shot and one with heat, defrost, high beams (and anything else you can turn on)
 
I have a 30 kWh Leaf with the same issue and my diff is about the same, too. In summer, my range was 130 - 140 km and my SOH was ~ 97%, then it dropped to 94% in a couple of weeks, but the BMS SW update brought it back to 97%.

At https://www.speakev.com/threads/permanent-40-60-mv-cell-diff-in-leafspy.127650/ , I discussed my data with others and involved Nissan as well. Nissan will not help, and dealers are not interested, not even when I say I am willing to pay for the replacement of the corresponding module. You can also try to talk to them, and you may be more lucky, but most likely you will see we are on our own.

Please share your experience if you find anything new, I am still looking for more information myself. On this forum, there are many threads related to our problem, e.g.

viewtopic.php?t=22667
viewtopic.php?t=18329
viewtopic.php?t=24282
viewtopic.php?t=24931
viewtopic.php?t=25287
viewtopic.php?t=21700
viewtopic.php?t=18103
viewtopic.php?t=17676&start=10
viewtopic.php?t=16070
viewtopic.php?t=18468
viewtopic.php?t=25178

My last attempt was my question at
https://mynissanleaf.com/viewtopic.php?t=24282 , which seemed to be the most relevant and promising thread (with a year’s history), but so far I have not got a reply. Perhaps that thread is too old, or its author no longer cares about the Leaf.
 
Thekuai said:
:idea:
LeftieBiker said:
THAT looks much more like a typical Leaf pack in need of normal balancing (by charging until all charging lights shut off at 100% indicated charge.

I'm new to leaf spy, why are some lines red and some blue? And why is module #87 or 88 still very low? So the leaf self balances at 100% SOC? I've read that bottom balancing (running the leaf down to almost 0) is unnecessary for the leaf as it has an advanced BMS. I heard it's only for people who build vehicles with salvaged batteries without BMS.

First, I was mistaken when I said it was normal. The low cell is still too low. I just overlooked it with that color scheme. Second, red lines are cells that are being actively shunted (balanced), so the pack is trying to balance itself. It just isn't succeeding with that one low cell.
 
I agree that it looks like you have a weaker cell that is dragging the entire pack capacity down. That one cell is probably constantly having power shunted into it from other cells and dropping your range.

Individual cell failures are quite rare, especially on 24kWh packs, but it does happen. More information can be found here:
http://evsenhanced.com/services/hv-battery-repair-and-re-balancing/

In the last picture you were at 40% SOC, which is still quite a bit of charge remaining. The graph will be a lot more telling at Very Low Battery warning (--- for miles remaining). If I were you, I'd try to take it down there and get a picture. I see a 250-300mv difference in my (very degraded) pack at VLBW, but only 20-30mv difference when charged to 80%. So it makes a huge difference what the SOC is when you're looking for cell differences. That said, my car triggers no individual cell error codes and the car does not unexpectedly go into turtle.

Again, heed the warning that a weak cell may trigger turtle far earlier than normal, so make sure you're careful as that could leave you stranded. However, if you have video evidence that your car does prematurely trigger turtle, that may help you pressure Nissan to fix the issue. I would video your dash towards VLBW in case that happens.
 
A single bad cell won't change pack capacity that much but it will prevent a huge portion of said capacity to be used. Driving to VLB is not likely a good idea as the owner will get stranded. Realize in these situations, the GOM can go from 50 miles remaining to Turtle in a mile. This has been reported here many times.

I would suggest (again) that you take two screenshots (in a readable format) one with cells resting and then another immediately afterwards with everything running putting as much load on the pack as possible for at least 5 mins.

In a balanced pack, the voltage drop should be a few 10ths. I am guessing that the voltage drop will be a few hundredths with the bad cell dropping several 10ths.
 
Back
Top