Sudden Motor Power Loss resulting in car stalled on the side of the highway - Nissan Leaf 2017 30 kWh Battery Pack

While driving on the highway (it was a cold day) a turtle sign popped up on my dashboard indicating “Motor Power Limited”. Simultaneously I experienced my battery dropping from 80% - 60% within a matter of seconds, and then slowly recovering back to what it was originally. Driving back home I started LeafSpyPro, and experienced another turtle mode this time dropping my battery from 60% to 40% and then recovering back to what it was originally (Event 1).

The next day while driving to the dealership my car suddenly goes into neutral (no audible warning). I pull over on the side of the highway, and stop the car completely (Event 2). I am then unable to enter back into drive mode. The car is stuck in park or neutral, but the entertainment system and the lights still work. Being stranded I call a tow to the dealership.

The dealership told me that the 12V was faulty, and that replacing it would fix the issue. I took them for their word, and payed out the inspection fee and the cost to replace the 12V thinking that the issue would be fixed.

I have no further incidents, until a week later when the car suddenly dies again going into neutral without warning (Event 3), leaving me stranded on a highway and requiring another tow. I am currently waiting for the first available appointment from the dealership. In the meantime, I parsed the log data from the initial 2 events, here are my findings:

https://imgur.com/a/gZrSfxF

The relevant DTC thrown up IMO was the following:
- P338C 0048 Cell Over Discharge Module24 EVC-121 (present for both Event 2 & 3)

Looks like there are a few bad cells that are causing the entire battery to shut down. This was exasperated by the low ambient temperature, during the days of the both events.
I think there is a safety problem with these cars that such failures can occur so suddenly. During leadup to both events high CP diff voltage was occurring for an extended period of time. The car should have entered turtle mode power earlier, or given some other indication that a failure might be imminent.

My questions are:
1. Is my assessment correct? Could the dealership be correct that a faulty 12V caused the failure and the resultant DTC.
2. What test does Nissan have to do specifically, to diagnose and replace this battery pack? I have found that Cell Voltage Inspection Test (CLVI) exists, but would that in itself be sufficient? Since both events occurred at low temperature, would this test be able to find the defect regardless? (higher ambient temperature for the next few days)
3. Why would the 12V battery voltage plummet so fast after the EV battery shutdown of Event 2?
4. What are the causes of the other DTCs?

The 12V battery will discharge quickly if lights and other accessories (especially HVAC fan) are left on after the main DC contactor opens (car shuts down). The car will go into power limited (turtle) mode when the lowest cell pair voltage drops to a certain threshold and it will shut down at a slightly lower voltage threshold. It is clear that you have a weak cell whose voltage drops excessively under heavy load (you can see the low cell voltage in your LEAF Spy screen shots).

It is not likely that the 12V battery is the issue since you had the car shut down after the dealer installed the new 12V battery. Also, the DC-DC converter keeps the 12V battery charged while driving.

You didn't specify which type/capacity battery pack you have, but given the model year I will assume it's a 30 kWh pack. That version of pack is notorious for poor performance, including rapid (overall) degradation and weak/bad cell pairs; this has nothing to do with the 12v battery.
Since your pack is (I believe) still under warranty, your discussion with Nissan should center around how/when they can diagnose/repair the weak modules (which you can do with LeafSpy). You have my sympathy, as this will neither be easy (convincing Nissan to do it) or quick (battery modules are not readily available). Trust me, I know: I just did this (on my own) for my 40 kWh pack with a replacement module from a salvaged pack.

Yes, the 30kwh "Lettuce Pack" is truly remarkable in the variety of its individual quality. Some are better than Lizard packs, some are just average, and quite a few are demonstrably worse than the original, terrible "Canary Packs." They exhausted Nissan's supply of replacements, yet some are still showing all 12 capacity bars after 5 years.

I just had a similar experience in my 2016 30kWh Leaf SV.
I was driving uphill in cold weather about 8 miles into my journey. I received the audible and visual "motor power is being limited" warning. But simultaneously, the car was suddenly only providing neutral or park! This was pretty dangerous on an uphill mountain road with not much shoulder (and of course no cell service to boot).
The car is currently in the shop being analyzed.
I didn't have LeafSpy running at the time. But once I was on the side of the road, I at least connected to get a couple screenshots from LeafSpy showing me the 12V battery voltage was about 11.3V. So I figured that must have been the culprit. But reading your story, I am guessing it's more likely some weak cells in the drive battery.
Leftiebiker: when you say the 30kWhr packs have "exhausted Nissan's supply of replacements" is that why I have read on this forum about 30 kWhr 4 bar losers having their batteries replaced with 40kWhr packs by Nissan under warranty?

Leftiebiker: when you say the 30kWhr packs have "exhausted Nissan's supply of replacements" is that why I have read on this forum about 30 kWhr 4 bar losers having their batteries replaced with 40kWhr packs by Nissan under warranty?

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I think that it's both that and not desiring to have to pay for multiple pack replacements on the same cars.

Similar to situation here to the OP with my '16 SV in a suburb of Minneapolis, MN. No super steep and long inclines, but temps in the single digits and lower, a pack that is on pace to be replaced this spring/summer and some cells that are weak (which just happened in the last 3 weeks). It's turned our trusty Leaf into a vehicle that doesn't wander far from the home when temps are <20F, avoiding speeds >50MPH and heightened our awareness of making sure the AAA card is on us when we drive it.

Some pictures attached at the URL below. One was me at a stop with the heater running and first noticed the "weak cell". The next was in the safety of my garage where I took a full series of LeafSpy pics.

https://1drv.ms/u/s!AmMHBcyzLWAx8K89Z3ZoHYghn5xg-Q?e=xbavfP

My only question is: Is it worth pursuing the replacement of these cells or is it better to "limp" along until the bigger prize happens - claiming the battery degradation warranty.

Just an update about my situation. I showed all the data to the service agent at my dealership, and they were very helpful afterwards. They agreed with my assessment about weak/bad cells in the car, but to confirm it they ran more tests. After talking with Nissan, the battery is going to be replaced. I was told that the battery was in stock last week, but now I'm being told that the battery is back-ordered. Reading through the forum, I'm not expecting my car back any time soon, but have been provided a rental from Nissan.

Ibby said:

I just had a similar experience in my 2016 30kWh Leaf SV.
I was driving uphill in cold weather about 8 miles into my journey. I received the audible and visual "motor power is being limited" warning. But simultaneously, the car was suddenly only providing neutral or park! This was pretty dangerous on an uphill mountain road with not much shoulder (and of course no cell service to boot).
The car is currently in the shop being analyzed.
I didn't have LeafSpy running at the time. But once I was on the side of the road, I at least connected to get a couple screenshots from LeafSpy showing me the 12V battery voltage was about 11.3V. So I figured that must have been the culprit. But reading your story, I am guessing it's more likely some weak cells in the drive battery.
Leftiebiker: when you say the 30kWhr packs have "exhausted Nissan's supply of replacements" is that why I have read on this forum about 30 kWhr 4 bar losers having their batteries replaced with 40kWhr packs by Nissan under warranty?

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Did you get the DTC thrown up? Mine showed the cell overdischarge DTC for both times it happened. I might be wrong on this one, but this error code should not be thrown up because of a faulty 12V.

I think our cars are getting to the age where the 12V might be changed, but my data shows that it was not the culprit for the failure.

zarniwoop said:

Did you get the DTC thrown up? Mine showed the cell overdischarge DTC for both times it happened. I might be wrong on this one, but this error code should not be thrown up because of a faulty 12V.

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Great news that Nissan worked with you to understand the cause and are making it right with a new battery pack (which I'm sure will be nice to have).

DTC question: Did you manually pull this after the 2nd failure or were you continuously logging it?

The reason for my question is that I want to make sure, that if this happens to me this winter, that I capture the correct data and the correct time to make my case to Nissan.

mn4az said:

zarniwoop said:

Did you get the DTC thrown up? Mine showed the cell overdischarge DTC for both times it happened. I might be wrong on this one, but this error code should not be thrown up because of a faulty 12V.

Click to expand...

Great news that Nissan worked with you to understand the cause and are making it right with a new battery pack (which I'm sure will be nice to have).

DTC question: Did you manually pull this after the 2nd failure or were you continuously logging it?

The reason for my question is that I want to make sure, that if this happens to me this winter, that I capture the correct data and the correct time to make my case to Nissan.

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I pulled up the DTC after the car stalled (The DTCs were also in the service report that Nissan gave me the first time I went in). LeafSpyPro does continuous logging if you enable it in the settings, but as far as I can see it does not show the DTC in the logs, or when they occur. But it does show individual cell voltages, the time, and lots of extra information, so it was very useful to identify the weak cells.

Appreciate the intel. I've got three "weak cells" (#30, #42 and #46) and logging enabled on my iPhone's LeafSpy Pro for every 2 seconds, but not seeing anything in the Files folder. Is there somewhere else I should look?

mn4az said:

Appreciate the intel. I've got three "weak cells" (#30, #42 and #46) and logging enabled on my iPhone's LeafSpy Pro for every 2 seconds, but not seeing anything in the Files folder. Is there somewhere else I should look?

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I have an android, so the location might not be the same. For me it was under a folder with the location of : data\com.Turbo3.Leaf_Spy_Pro\files\LOG_FILES.

Ah... I have an iPhone. Anyone know of LeafSpy logging works on an iPhone?

An update on my situation....
My Nissan dealer finally got a "Nissan engineer" to review the information from my car. Nissan has now authorized replacing my old 30kWhr battery pack with a 40 kWhr battery pack. That's the good news.
The bad news is I have no idea how long this will take and the local Nissan dealer will only give me a rental car for 3 days!
Although, I have LeafSpy Pro, I don't think I had it running at the time of the failure. And like the previous poster, I have an iPhone and don't know where to even look for the log files to see what error codes may have been thrown during the event. I haven't received any details from the dealer (other than the battery is going to be replaced) so I don't have any technical details to share about my event. I hadn't noticed any weak cells when looking at LeafSpy previously. But perhaps I wasn't looking at it during "high stress" events on the battery (ie cold temps, high load, etc.)

A question for others. I would love to think that Nissan will give me a NEW 40 kWhr pack. But in the back of my mind, I wonder if they will give me a USED 40 kWhr pack with the assumption that as long as it still has at least 30 kWhr of capacity they are making me whole. I guess I'll find out once I get the car back. And I'll post an update then.

Nissan appears to use new packs, even though that isn't required.

This happened to my 2017 Leaf S today when my daughter was driving it. The outside temperature went down to -15°C overnight (5°F) and all was fine until about 10 minutes into the drive when on the highway (100km/hr) it said power limited and she said there was strange shaking and hesitations when trying to keep up the speed... she took the first exit and the shaking and message went away after slowing down. Back on the highway the shaking started again around 100km/hr but went away when driving slower. She safely made it to her destination, and hopefully she makes it back this afternoon. (Edit: she made it back, but had to keep speed at under 100km/hr)

I have Leaf Spy, so I'll definitely have it running when I'm driving.

What do you recommend for me have available when I report this to my dealership? Unfortunately it is now past the electric system warranty, so I only have the battery warranty to fall back on.

rodenti said:

This happened to my 2017 Leaf S today when my daughter was driving it. The outside temperature went down to -15°C overnight (5°F) and all was fine until about 10 minutes into the drive when on the highway (100km/hr) it said power limited and she said there was strange shaking and hesitations when trying to keep up the speed... she took the first exit and the shaking and message went away after slowing down. Back on the highway the shaking started again around 100km/hr but went away when driving slower. She safely made it to her destination, and hopefully she makes it back this afternoon.

I have Leaf Spy, so I'll definitely have it running when I'm driving.

What do you recommend for me have available when I report this to my dealership? Unfortunately it is now past the electric system warranty, so I only have the battery warranty to fall back on.

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I'm guessing that your battery has some capacity loss (3 bars perhaps?) and this is just the BMS system protecting itself. Very likely, reporting it won't get you much. At least this is the case in the U.S. YMMV in other countries.

On cold days the only thing you can really do is: Time the battery to be done charging before the car leaves, preheat the car while on shore power, drive slower.

mn4az said:

I'm guessing that your battery has some capacity loss (3 bars perhaps?) and this is just the BMS system protecting itself. Very likely, reporting it won't get you much. At least this is the case in the U.S. YMMV in other countries.

On cold days the only thing you can really do is: Time the battery to be done charging before the car leaves, preheat the car while on shore power, drive slower.

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Two bars lost, most likely getting close to three bars but I haven't checked the battery health with Leaf Spy since the summer.

If it happens often, or someone gets stranded, I guess I'll have to bring it into the dealership... but until then I'll try to follow your advice. The car is set to automatically heat up every weekday morning, but I'll change that to every morning until we get past the coldest winter months.

rodenti said:

mn4az said:

I'm guessing that your battery has some capacity loss (3 bars perhaps?) and this is just the BMS system protecting itself. Very likely, reporting it won't get you much. At least this is the case in the U.S. YMMV in other countries.

On cold days the only thing you can really do is: Time the battery to be done charging before the car leaves, preheat the car while on shore power, drive slower.

Click to expand...

Two bars lost, most likely getting close to three bars but I haven't checked the battery health with Leaf Spy since the summer.

If it happens often, or someone gets stranded, I guess I'll have to bring it into the dealership... but until then I'll try to follow your advice. The car is set to automatically heat up every weekday morning, but I'll change that to every morning until we get past the coldest winter months.

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If the car stops moving forward, like with the OP, it's likely because it's thrown a DTC error. At that point the dealership will be helpful in replacing the cell(s) or whole pack.

Following this thread closely for updates, I just had this happen to me too today while driving my 2016 to work — near freezing temperatures, driving a bit uphill, drive cuts out while I’m trying to accelerate on I-25S heading into Denver. Got pulled into shoulder & couldn’t re-engage drive, would only do N & P. Took a couple hours for AAA dispatched truck to get to me (quite not fun but at least wasn’t snowing…). Nissan basically says won’t likely get news until Monday but if is HV battery would likely be 6 months wait. I happened to have ODBII in car and LeafSpy showed pretty much exactly the codes others have posted. My battery is just barely 9 bars with 66.9 SOH — soooo close but maybe I’ll get lucky. Suspect they’ll first want to replace 12V.

Anyways hope to hear what happens with you all’s Leafs.