Traction Battery Cut Out

Hello All, I've searched best I can to see if anyone else has posted about this topic, found nothing. If I missed the answer please just post the link. TLDR: Tracton battery cut out at high speed twice, car reset itself after 1-2hours. Car is working fine otherwise.

Long story. So winter 2020 it was really cold for about a week. Like -10F for a week. Late afternoon, just before sundown I was driving my 2017 Nissan Leaf (30kWh) in the minus 8 degree Fahrenheit cold on the freeway, in the fast lane at about 75mph. Battery was at about 78%. Heater was off but I was circulating air to keep the frost off the windshield.

Without any warning from the dash or driving experience, the car lost all power. It felt like I had taken my foot off the accelerator pedal. Or if any of you have ever hit the top limit on speed (90ish) with your Leaf, it cuts out till you slow your butt back down. I wasn't going 90ish fast for that to happen. Naturally, I pressed down harder. Nothing happened. At about that moment there was a beep, The same beep you get if you try to shift without pressing the brake, and a message on the radio that said something like "Vehicle unsafe. Tow to nearest dealership" Mind you, I was going 70ish now and I didn't get a good look. My focus was getting out of the fast lane and over three lanes to the shoulder. I did NOT want to be dead on the left shoulder. Very heavy traffic. I safely navigated to the right shoulder and came to a stop.

The car had put itself in neutral. It would not shift info drive or reverse. The dash was on. The radio had the same message about "unsafe" to drive and "towed" and "dealership" I really wish I had taken a photo of it. I shut the car off using the start button. It re-booted normally but then just beeped. The same beep you get if you try to shift without pressing the brake. The scary "unsafe" message did not reappear. Could not shift it into drive, reverse or neutral.

So it's minus 8F and I'm dead on the side of a rural stretch of I-25 with no heat. Tiny bit of panic. Immediately called my insurance and they started to arrange a tow. Bad cell service, several dropped calls. Finally got the tow ordered. Called friends who immediately came with their ICE car. More bad calls, tow truck can't find us. Second truck is called, cell quality is so bad he can't really figure out where we are. After about 2.5 hours the second guy pulls up behind. Then the 1st guy about a minute later. God bless those guys, looking really hard for us.

It's so cold tow guy does not want to go thru the winching process and asks if I'm SURE it won't start. I agree to humor him. To my surprise, it boots right up, NO beep. Shifts into drive, my window is down and I say, "it works!!!" He says to drive it right up on the flatbed, so I DO. Pretty sure insurance does NOT allow the customer to do that. He hooks the car, I jump out and slide down the ramp. And we go back to my house. He climbs in and it starts right up. Drives it right off the tilted flatbed. No issues whatsoever.

It sits on the street overnight. Next day it starts right up and I move it to the Level II charger in the garage. Worked fine, no issues, warnings, etc since.

Until November 4th, 2022. Not quite as cold, 27F, battery at about 16%, on the same freeway but 2 miles from home. Going really fast, like 80ish, getting around a traffic blob. Dumb yes, but that's what I was doing. Same thing happened. Cut out. Beep. Coast to the side of the road. Same message about "unsafe" to drive and "towed" and "dealership" I did not think to photo it. McDonalds was right there, next to the exit so I got out and walked there. Waited an hour, walked back to the car and it started without any issue. Like nothing happened.

Brings me to now. I was really hesitant to post. I didn't the 1st time as this sounds really bad and I don't want to contribute to the FUD around electric cars. Now that it has happened twice I'm a little worried about driving it. We've been 12F all week overnight and I don't really want to sit in a freezing car for an hour hoping it will magically clear itself. If it happens again I am ready for it and I WILL take pics and LeafSpy right when it happens.

Anyone have any clues as to what is going on? I'm pretty sure if I go to Nissan they will charge me $400 to have a look and say nothing is wrong. I do have LeafSpy Pro and nothing seems out of the ordinary. But I could be missing something.

Welcome. There are two main possibilities here: either your 12 volt battery is bad, or, since this is a battery that has known issues, you may have one or more marginal cells that are triggering the shutdowns under high loads. Look at (and post here, if possible) the cell histogram provided by LeafSpy. Is there one or more cells with much lower voltage than the rest? What is the max voltage differential?

The premium edition of LeafSpy will display DTC's

Lefty, OP says that the first time it happened SoC was 78%. That makes me think a weak cell is not the culprit, although it sure was my first thought.

A weak cell doesn't need a low SOC when there is a large load instead. Low SOC helps to trigger marginal cells to sag, but it isn't a prerequisite.

LeftieBiker - Believe it or not, I have 3 Nissan Leafs. 2011, 2013 and the 2017. The 2011 is smashed in the front end and I will eventually be building a project out of it. The 2013 was having weird charging issues last week and the battery was weak, 9v ish, disconnected. It was 9 years old. I put the 2017 12v battery in it, seems to have fixed it. I bought a new 51R at Costco and put that into the 2017 cuz I was a bit lazy in the 25F temp and didn't feel like pulling the '17 battery out of the '13. Plus I've had a bad cold:-( So the '17 has a new 12v battery as of this week.

The last time I did a LeafSpy there were no cells that stood out. That was one of my suspicions the 1st time it happened but, nope LeafSpy looked good, level. As for the 2nd time, I will get a screenshot soon. Have to set it up on a new phone.

I agree with you: "A weak cell doesn't need a low SOC when there is a large load instead. Low SOC helps to trigger marginal cells to sag, but it isn't a prerequisite."

This is what I was thinking. Very large load (driving very fast) plus the low temps.....batteries don't like the low temps, one cell sags and then we get the emergency shutdown. To be honest, the emergency shutdown is what has me worried. I've searched for it and haven't found anyone posting anything like it. I wish I had the exact wording of the message to search with.

I think I'm going start driving with LeafSpy running all the time. If there is a log feature I need to enable that.

SageBrush, that was my very first (hopeful) thought too, can't be the pack at 78% but then got to thinking about it and arrived at the same thought as LeftieBiker

Was the new 12 vol battery charged fully before it was installed? I'm harping on that because the only other time I remember seeing this full set of symptoms, it was a dead 12 volt battery causing the shutdown. You may want to check the battery cables, including the second ground bolt that looks like it's just a cable mount. An intermittent open in the 12 volt battery circuit could be the culprit...

These items (collectively) scream bad cell(s) in the pack:

• 30 kWh pack (notoriously bad)

• cold temps (bad for batteries in general)

• high speed (maximum stress)

• sudden shutdown

I have been tracking a weak cell in my pack, and (recent) cold temps only make things worse. Nissan won't do you any good, as they only want to replace packs (or sell you a new car), not open it up and replace individual modules (of which none are available anyway--trust me).
I am working on replacing my weak cell/module, and suggest you start monitoring your pack closely (with LeafSpy). And be especially careful on the highway. Drive safe!

DnvrMike said:

I agree with you: "A weak cell doesn't need a low SOC when there is a large load instead. Low SOC helps to trigger marginal cells to sag, but it isn't a prerequisite."

Click to expand...

A cell voltage historgram shot at a SoC of under 78% will be proof, but consider some common sense arithmetic: A SoC of 78% is about 3.8V average per cell. A weak cell would have to be in the neighborhood of under 3v to have any chance of sagging enough under load to cause problems, so the weak cell would have a delta of 800 mV at 78% SoC. Did you miss an 800 mV delta ? I didn't think so.

The other common sense point is that IF such a cell was present, you would have noticed severe range performance issues, along the lines of "When I charge to 100% the car says I have 100-ish miles range, but then I only get around 30-ish with non-aggressive driving !"

Some weak cells only experience large voltage sags under heavy loads. They don't show sags that are proportionate to SOC and load - they behave ok at first anyway, only sagging when pushed hard.

LEAF Spy Pro has a logging function (creates spreadsheet files with a lot of information). It must be enabled in settings and you need to select how frequently it records. You should set it to record every few seconds for your particular needs to analyze this shutdown condition. Internal resistance is higher when the battery pack is cold, but heavy current draw should help to keep the battery warm unless the shutdown was soon after starting the trip (before the high current could warm the battery). Weak cells will generally cause Turtle (power limited) mode at least briefly before shutdown. Check coolant levels since the inverter or motor getting too warm under heavy load might lead to sudden shutdown.

Did you ever get this resolved?

I had the same thing happen to me a few times this week, battery would unexpectedly drop and "power to the motor is being limited would be displayed. After 10 seconds or so of slowing down and merging over, the message went away and the SoC percentage recovered. However this time, driving normally on the highway, the SoC dropped to less than 5% (displaying the dashes) within a mile, and cut power output to the point that I couldn't even maintain speed. I coasted to an exit and was pretty much stuck dead blocking that lane of traffic. The vehicle was stuck in accessory mode and any attempt to power on the traction system (using the brake) did not work. After cutting the 12V system by disconnecting the battery for a minute, everything came back up as if there was never any issue. the SoC even went from unknown/dashes to what I would have expected the battery to be. It as if the computers needed a HARD reset to realize the condition was cleared.

I have taken it in for diagnostics ($150 charge) and they have so far said that there are no logged DTCs so I am afraid they are going to charge me and refuse to acknowledge that there is a problem because they cannot "reproduce the issue".

nfettinger said:

Did you ever get this resolved?

I had the same thing happen to me a few times this week, battery would unexpectedly drop and "power to the motor is being limited would be displayed. After 10 seconds or so of slowing down and merging over, the message went away and the SoC percentage recovered. However this time, driving normally on the highway, the SoC dropped to less than 5% (displaying the dashes) within a mile, and cut power output to the point that I couldn't even maintain speed. I coasted to an exit and was pretty much stuck dead blocking that lane of traffic. The vehicle was stuck in accessory mode and any attempt to power on the traction system (using the brake) did not work. After cutting the 12V system by disconnecting the battery for a minute, everything came back up as if there was never any issue. the SoC even went from unknown/dashes to what I would have expected the battery to be. It as if the computers needed a HARD reset to realize the condition was cleared.

I have taken it in for diagnostics ($150 charge) and they have so far said that there are no logged DTCs so I am afraid they are going to charge me and refuse to acknowledge that there is a problem because they cannot "reproduce the issue".

Click to expand...

Any update on this? My car broke down like this twice, both in a similar manner. I was driving at high speeds on the highway, and the car enters "Limited Power Mode". About 5s later the car goes into a neutral, and warns me to stop the car immediately. I pull over and am unable to shift the car into Drive. It would only go into Park or Neutral. The dashboard, and the entertainment system were still working. I get stranded on the side of the highway on the shoulder, and had to get the car towed to the dealership. They told me it was a faulty 12V battery in front. I replaced it like they said, and about a week later the car breaks down on the highway again in a worse place.

After paying out for another tow to the closest dealership (different one) and leaving it overnight (service centre was closed), the car is able to shift into drive. The service representative told me that the dealership would charge me for another diagnosis, because the work was done at another place. She also told me that my warranty for the 30kWh battery was voided because I didn't buy their annual battery health report. :?:

I ended up driving back slowly taking surface roads back to my place, with a socket wrench just in case i need to disconnect the 12V to reset the car again. Currently waiting for the first appointment at the 1st dealership I went too. I did end up recording the following from LeafSpy the 2nd time around, while stranded on the highway:

https://imgur.com/a/CtzLoLk

Based on the trouble codes and the value of the 12V battery shown in LSP, it does appear to be a case of a bad or weak 12V battery. Did you fully charge the replacement 12V battery before installation? If it was stored at less than full charge and installed that way, the charging system of the Leaf may have never fully charged it. I'd charge the 12V battery with an external charger and clear all the trouble codes before paying any more money to a dealer.

As for the warranty, you're getting close to the mileage limit but I've never of anyone being denied a replacement battery due to not having the annual battery check done. Be sure to contact another dealer or better yet, a corporate or regional Nissan representative before settling that issue.

goldbrick said:

Based on the trouble codes and the value of the 12V battery shown in LSP, it does appear to be a case of a bad or weak 12V battery. Did you fully charge the replacement 12V battery before installation? If it was stored at less than full charge and installed that way, the charging system of the Leaf may have never fully charged it. I'd charge the 12V battery with an external charger and clear all the trouble codes before paying any more money to a dealer.

As for the warranty, you're getting close to the mileage limit but I've never of anyone being denied a replacement battery due to not having the annual battery check done. Be sure to contact another dealer or better yet, a corporate or regional Nissan representative before settling that issue.

Click to expand...

Thanks for the input! I do not know the state of charge that the 12V had before installation. The dealer installed it for me, so I just assumed everything was all good. But the 2nd incident happened about 2 weeks afterwards. I drove mostly highways during that time. Like the first incident, the failure occurred at low ambient temperature, and high power draw.

I will try resetting the error codes as you mentioned and monitoring the car for the next few days.

So DnvrMike and Zarniwoop, I am joining your club.
Same thing happened to me. Driving uphill in the cold (so high load), I lost power. After pulling off the road, I only had neutral or park available (while the dashboard, radio, and all electronics were still operating fine).
Car is in the shop being analyzed. I'll let you know what happens.
Mine is a 2016 Leaf SV with 30 kWhr pack (with BMS update applied). I have 43,000 miles on it. 3 bars lost so far.

+ 1

Documented my experience here: https://mynissanleaf.com/viewtopic.php?p=628374#p628374

However, after reading this thread I figure it *might* be time to finally replace my original 12V battery.

Every time I read a post that says 'Power lost, but I'm told everything is fine," it re-affirms my decision to get Nissan and its cars out of my life.

SageBrush said:

Every time I read a post that says 'Power lost, but I'm told everything is fine," it re-affirms my decision to get Nissan and its cars out of my life.

Click to expand...

Every time I look at Twitter, I'm happy I never got a Tesla.

No car is perfect. No company is perfect. No car dealer is perfect. No mechanic is perfect. And so on.

My LEAFs have been outstanding cars. No serious trouble. Less maintenance. Comfortable, smooth and quiet. Responsive and enjoyable to drive.

WetEV said:

SageBrush said:

Every time I read a post that says 'Power lost, but I'm told everything is fine," it re-affirms my decision to get Nissan and its cars out of my life.

Click to expand...

No car is perfect. No company is perfect.

Click to expand...

Forget 'perfect.' That is a strawman. Every other company I can think of that is selling in the US is magnitudes better than Nissan. I include GM in that comparison, and that is saying something since GM takes 'awful' in stride. But Nissan and its dealerships are misery, incompetence, reckless neglect, and outright assholedness all rolled into one

SageBrush said:

Every time I read a post that says 'Power lost, but I'm told everything is fine," it re-affirms my decision to get Nissan and its cars out of my life.

Click to expand...

Depends on the perspective. If you are a car mechanic, you see weird stuff all the time across all vehicle makes. My friend runs his own repair shop and just repairs expensive luxury vehicles all day with what seems like simple stuff that shouldn't be a problem on vehicles costing +$100k, but that also doesn't mean a car mechanic can be versed it all things possible cars. They have to lookup and research problems just like anyone else would.

I can't speak to the other vehicles Nissan makes, but I've done my own vehicle maintenance on many ICE vehicles for the last couple of decades and the Leaf has been the most maintenance free vehicle I've ever owned. Oil changes are one thing, but having to perform major engine maintenance that requires lifts and taking everything apart just to change out one sensor or one valve or one belt is never desired for any vehicle owner.

At the same time though, I have the tools to diagnose a lot of common problems for the Leaf via reading this forum and helping friends and family that own Leaf as well, my view is just opinion of course. :mrgreen: