[help] Rapid battery discharge, "limited motor power", and sporadic power output at temp. < 30F and > 40% motor power.

Video of behavior where rapid discharge becomes apparent at 40s:
https://youtu.be/dULaMW2cUXQ

Rapid (reported) battery disharge in low-ish temps and moderate-high power output

My 2013 Leaf @ 57k miles experiences rapid (reported) battery discharge followed by a "limited motor power" warning and sporadic drivetrain power output (which can be scary). This happens when requesting more than 40% power for more than 10-20s, in ambient temperatures of around 30°F or less. Once power is no longer requested (i.e. you stop the car), the reported remaining charge will slowly climb back to where it might have been had the rapid discharge event not taken place. This can be seen towards the end of the video.

I've taken my car to a dealer, and they said this was caused by "normal battery capacity degradation", but I disagree. The battery capacity has certainly lowered, but a lower capacity equates (in my mind) to "less range per full charge", which is very different from "99% less range when it's kind of cold, and normal range when it's slightly warmer." I'm reaching out to you all to help diagnose the issue.

The discharge rate can be as high as 2 to 3 percent PER SECOND if more than 80% power is requested. In the video I'm requesting 50% power and it drops from 50% to 36% in 17 seconds (0.82%/s). If the ambient temperature is above 40°F this does not happen at all; no significant increase in discharge rate, and no "limited motor power". For comparison, see https://www.geotab.com/blog/ev-range/, where I should (according to their plot based on a broad range of BEVs and over 4 million trips) expect a range decrease of around 10% due to a decrease from 40°F to 30°F (very similar to the data for only Nissan Leafs here: https://www.greencarreports.com/news/1082048_nissan-leaf-range-how-much-does-it-lose-in-the-cold). Also see https://avt.inl.gov/sites/default/files/pdf/fsev/2015LeafColdWeatherTestJune2016.pdf, a study based entirely on 2015 Nissan Leafs, where the range decreased from ~75mi to ~65mi (figure 5 on page 7) due to the same decrease in temperature. What I'm seeing is a temperature regime where my range drops from 50 or more miles to essentially 1 or 2 miles.

As you can see, my battery is at 7 "bars", so it's not a spring chicken, but I still get 50/65 miles of range in the winter/summer, which is proportionate to what you would expect based on its initial range and its reported health. Under the rapid discharge conditions shown in the video, however, the car will drop from 75% to 0% in less than two minutes.

I see this as a "failure", in that the car is nonfunctional (and dangerous, as the sporadic power output tosses the car back and forth). Further, the fact that the behavior is completely different at 30°F than at 40°F, it seems like there is something failing that causes this behavior.

Possible causes

To me, this looks like a voltage issue. As I mentioned above, after you stop the car, the reported remaining charge will slowly climb back to where it might have been had the rapid discharge event not taken place. So the charge isn't "going" anywhere; the car is erroneously reporting a lower remaining charge than what is actually in the battery.

Remaining charge is estimated using the output voltage of the battery, so for the car to report a lower remaning charge means that it thinks that the voltage from the battery is dropping dramatically. This could be one or both of two things:

1. The voltage from the battery is actually dropping FAR BEYOND even the worst expected case for battery voltage as a function of temperature, or
2. There is a sensor (perhaps a voltmeter, or a thing the voltmeter is connected to) somewhere that is, under the conditions of cold-ish and a moderate-high load, failing and providing erroneous voltage readings, causing the remaining charge estimate to lower.

I'm ambivalent to which one it is. I just want my car to not suddenly die and swerve off the road every time I go uphill in barely freezing temperatures. A new battery would be nice but unnecessary as the Leaf's current range is sufficient.

Insufficient battery voltage

The technician has already looked over the battery, and says he's confirmed that there are no leaking cells, and the car isn't reporting any diagnostic codes related to battery failure. That being the case, if it is actually the voltage from the battery that's dropping, then I'm at a loss for what the underlying cause might be given that it's not obvious to the techs.

Since this is a problem causeed by low temperature I thought about the battery heating/cooling. I know that the battery "warmer" doesn't come on until the battery temperature drops to -1°F, and then it turns off once the battery temperature has climbed back up to 14°F, and only if the reported remaining charge is > 30% (page EV-5 of owners manual https://owners.nissanusa.com/content/techpub/ManualsAndGuides/NissanLEAF/2013/2013-NissanLEAF-owner-manual.pdf). That doesn't seem to apply here, hence I can't think of what it might be.

Bad sensor

If the problem is a sensor or some intermediate chip between the sensor and the car computer, then I guess they could test it (in a freezer?) with a known voltage and isolate the problem.

That's all I have on it. I'd appreciate any help approaching the issue, or tips for what the technicians might do to diagnose the problem.

It's likely a bad cell or three in the battery. Hopefully your car hasn't yet reached 8 years passed the In Service date, because until then it's covered by a 8 year, 80k mile (IIRC) defect warranty.

What tire pressure are you running--Do you have a low or flat tire?

What is the age and condition of your 12V auxillary starter battery? Voltage at rest and when in ACC mode? Cold temperatures are rough on the aux battery, and if it is old, weak or worn out it could contribute to this problem. i couldn't see if the aux warning lamp came on.

There have to be DTCs stored under these conditions when either the yellow or red warning lights on the instrument panel come ON. If they won't tell you the codes then you will need to get a scan tool and read them yourself. The DTCs will tell the story of what is happening.

It could be weak cells in the pack that lay down under load, but there is a DTC for that.

Rotate your phone to get the entire IP, couldn't see the temperature gauge or DTC lamps on the left side.

As Leftiebiker said, you most likely have a few weak cells. I started to see premature power-limited mode under higher power draw conditions along with greatly reduced range on my 2015 toward the end due to several weak cells (clearly shown by Leaf Spy cell voltage graphs). Your battery defect warranty should be 8 years or 100,000 miles, but Nissan will probably not do anything until it gets bad enough to set error codes (DTC's). As you noted, gradual capacity loss is just that--gradual and somewhat consistent. The Leaf's LBC (lithium battery controller aka battery management system or BMS) calls for power limited (turtle) mode when the voltage of the lowest cell drops below a threshold so a weak cell under high current draw causes that condition even when there is considerable energy left in the battery pack. After you slow down or stop, the voltage of the weak cell(s) recovers and the car drives normally. In your case, it will likely get worse until it either sets some error codes or the ambient temperature warms up. The internal resistance of the cells increases in cold temperatures which makes the situation worse.

Find out when the "In Service" date (usually the day the dealership registered the car to you or the first owner or lessee) is for the car. You have exactly 8 years and 100,000 miles from that date in which to file a battery defect warranty claim - not a second or mile longer. If this is easy to reproduce, take a Leaf-certified Nissan tech with you on a ride, when the car is low on charge, and goose it up a few steep grades. Nissan will still require that DTCs have been set, but having a Leaf tech confirm that the issue exists should help you.

Thanks for the quick replies everyone!

Not gonna lie. It feels really good to have people agree that is sounds like a voltage issue.

I'm going to buy Leaf Spy Pro and a DTC reader and put together a proper case to try and both sway my technicians and the warranty folks at Nissan. The tech did mention that it hadn't thrown any DTCs regarding bad cells. Hopefully it will throw some while I troubleshoot and build a case (and collect better video of the behavior).

My 8 year warranty expires April 24, 2021, so the clock is ticking, but I have three more cold months in which to try and gain coverage. The language in my warranty booklet regarding the 8-year Li-ion battery warranty is so vague as to be useless. It "...covers any repairs needed to correct defects in materials or workmanship...." The exclusions list (none of which apply) is prefaced with a bit more information, saying that "...damage or failures..." are not covered if any exclusion is met.

I would definitely say that what I'm experiencing is a failure. The car is non-functional in these circumstances. But it does come down to the definition words like "defect" and "failure" which aren't explicitly defined anywhere in the warranty booklet. I feel like there must be a more complete document somewhere, but then again I think they'd have to provide that to the customer in the warranty booklet in order for the language to be considered legally binding. Perhaps there's a more thorough document you sign when you buy the car and the warranty booklet is more concise?

You don't have to worry much about the semantics of the battery defect warranty. You get those DTCs, and the pack will be replaced. They have the option of just replacing bad cells, but they generally only do that with new and new-ish packs with defective cells.

This thread should be a sticky.

EXCELLENT video of a bad cell(s).

OP: Was your complaint formally recorded at the dealership, and do you have that record ? That might be the date used for warranty determination, or it might be the date that the dealership identifies DTCs. Hopefully the former, but I am not sure.

Be sure that your recorded complaint says this:
1. When fully charged, the car can drive 50 miles on level ground. At half charge, the car loses power driving up a hill.
2. This loss of power driving up a hill when more than adequate energy remains in the battery is a performance defect and a profound, immediate SAFETY issue to yourself and to other cars around you.

The safety angle is thrown about with abandon in the USA, but your case has the advantage of it being correct. If the UK has regulatory authorities that accept consumer vehicle safety complaints then I think you should mention to your dealership that they either address the safety issue yesterday or you will be forced to report their actions. You should also call and write Nissan. Keep your communications civil and to the point, and keep a paper trail.

This is all presuming your battery is still under warranty for defect: UNDER 8 years from when the car was put into service, AND UNDER 100k miles.
<addendum> Odometer is ~ 87k miles.

@GerryAz, if turtle does not cause a DTC in this situation -- what does ?

I watched the video again. OP puts the car under a modest load that leads to a 'power limited' condition. Is that the same as 'turtle mode.' ?

I imagine it should be a simple exercise to put a dealership tech into the car on a quiet street or lot when the SoC is 30 - 40%, stomp on the go pedal and watch the car roll over and light up with error codes.

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<rant>
It is amazing just how incompetent Nissan dealership "LEAF" technicians can be, and how common they are.
People thinking of buying a Nissan EV really should factor this sorry state of affairs into their purchasing decision.

When you going to check your tire pressures?

You have a weak cell. Weak cells suffer much larger voltage drop under load which triggered your limited power warning. Notice you lost one power circle? It came back immediately when you let off the accelerator. Your SOC also rose a bit after you stopped.

This is typical of a weak cell. They charge the fastest and are depleted the fastest. This is a workmanship warranty issue which is covered for first 8 years or 100,000 miles (unless its CA... I think) so take it in.

SageBrush said:

I watched the video again. OP puts the car under a modest load that leads to a 'power limited' condition. Is that the same as 'turtle mode.' ?

I imagine it should be a simple exercise to put a dealership tech into the car on a quiet street or lot when the SoC is 30 - 40%, stomp on the go pedal and watch the car roll over and light up with error codes.

----
<rant>
It is amazing just how incompetent Nissan dealership "LEAF" technicians can be, and how common they are.
People thinking of buying a Nissan EV really should factor this sorry state of affairs into their purchasing decision.

Click to expand...

No. Turtle mode is "irreversible" or at least doesn't come and go w/o a clearing of the codes, etc. He got the message because he lost one power circle (double wall to single wall) Depending on cell balance (his is pretty bad) Turtle mode will come on after losing 4 circles or so

DaveinOlyWA said:

SageBrush said:

I watched the video again. OP puts the car under a modest load that leads to a 'power limited' condition. Is that the same as 'turtle mode.' ?

Click to expand...

No. Turtle mode is "irreversible" or at least doesn't come and go w/o a clearing of the codes, etc. He got the message because he lost one power circle (double wall to single wall) Depending on cell balance (his is pretty bad) Turtle mode will come on after losing 4 circles or so

Click to expand...

I was not aware of the single and double circles. Good to know

If I saw the circles correctly, between 3 or 4 became single circles just before the 'power limited' light came on.
What would have happened in terms of alerts and DTCs if OP had pressed on the go pedal harder once the power limited light turned on ? Or perhaps a better question, how would you expose the weak cell by causing turtle mode ?

SageBrush said:

DaveinOlyWA said:

SageBrush said:

I watched the video again. OP puts the car under a modest load that leads to a 'power limited' condition. Is that the same as 'turtle mode.' ?

Click to expand...

No. Turtle mode is "irreversible" or at least doesn't come and go w/o a clearing of the codes, etc. He got the message because he lost one power circle (double wall to single wall) Depending on cell balance (his is pretty bad) Turtle mode will come on after losing 4 circles or so

Click to expand...

I was not aware of the single and double circles. Good to know

If I saw the circles correctly, between 3 or 4 became single circles just before the 'power limited' light came on.
What would have happened in terms of alerts and DTCs if OP had pressed on the go pedal harder once the power limited light turned on ? Or perhaps a better question, how would you expose the weak cell by causing turtle mode ?

Click to expand...

Too much power could trigger turtle mode which would require a recharge to clear. A bit inconvenient since he still had some bars left. The action of the pack should clearly show the bad cell with minimal power needs.

DaveinOlyWA said:

SageBrush said:

Or perhaps a better question, how would you cause turtle mode in order to expose the weak cell(s) ?

Click to expand...

Too much power could trigger turtle mode which would require a recharge to clear. A bit inconvenient since he still had some bars left. The action of the pack should clearly show the bad cell with minimal power needs.

Click to expand...

Read the OP: the technician was clueless and was only able to report that no DTC was logged.

I'm trying to come up with a scenario for OP to use that will not result in a towing fee but will present the dealership with a DTC that has to be investigated.

How about this:
Show up at the dealership with a cold battery, and with under 30% SoC
Gun the car to induce a DTC
Drive the few meters in turtle mode into the dealership

If you have a better way, by all means share.

SOC under 20%, take the tech for a short drive, then either climb a hill with full "throttle" or accelerate at full throttle. Stay near the dealership. The lower the SOC, the more likely a DTC will appear.

Easiest way is simply drive until Turtle mode shows up near dealership. Limp to dealership and ask them why the Turtle is showing with 3 charge bars still showing.

(I'm so glad I reached out. You're all awesome and a breath of fresh air.)

Re. the low tire pressure @DaveinOlyWA. I think it's a bad pressure sensor. Comes on in the cold and goes away at over 50°F or so. When I check they're never low.

@SageBrush: I've recorded my interactions thus far, but haven't registered a formal complaint, although that does seem to be the next recourse given my technician saying "Look, you say it's voltage, we say it's a capacity issue, and that's just our determination". I will absolutely stress the safety issue. And about the incompetency of "certified" Nissan EV techs, I couldn't agree more; they're either truly incompetent (in this case) or completely dishonest. I really feel like he's been gaslighting me this whole time. ("Oh no, this is exactly what a capacity issue looks like," he said to me when I suggested that this looked like voltage rather than capacity.)

And thank you for pointing out the single and double circles in the power meter @DaveinOlyWA; hadn't known about those.

I'm waiting on a DTC reader to use with Leaf Spy. I was expecting that I could trigger the DTCs during my testing regarding which cells report low voltage and under which conditions, but if I'm reading your replies correctly @DaveinOlyWA, the DTCs related to turtle in my case will go away when the car is charged?

Re. the suggestions to try and raise codes when at a lower SOC, can someone explain why it might throw codes at low SOC, but not at e.g. 75% SOC even though the underlying cause is supposedly the same?

At this point my plan of action is to

1. replicate this issue with Leaf Spy recording (probably by heading up the mountains via freeway in the cold), and
2. also record with Leaf Spy the cell voltage behavior while charging. I'm planning on charging at 6.6kW, assuming it will better expose voltage issues than a 1.5kW trickle charge. Should I instead use a 50kW DC charger to better show voltage when charging?
3. See if I'm able to achieve a more permanent turtle mode by flooring it at low SOC, then
4. With the data, and more videos in hand, I'll then show up in turtle mode ready to lodge a complaint with the manager if they continue to assert it's just "normal battery capacity degradation".

And just to confirm my suspicion, the sources I linked to in my post showing typical temperature effects on EV range are useless in whatever case I lay out, yes?

Re. the suggestions to try and raise codes when at a lower SOC, can someone explain why it might throw codes at low SOC, but not at e.g. 75% SOC even though the underlying cause is supposedly the same?

Click to expand...

The problem is differences in capacity between the cells, resulting in differences in voltage as they discharge. When the cells have lots of charge, those differing voltages are still close together. As the bad cells near empty, though, while the good cells stay well charged, the voltage differences increase, because discharged cells have substantially lower voltages than charged ones. Below 20% charge the imbalances start to near the trigger point for the battery management system (BMS) to sound the alarm (DTCs) and act to protect the pack from permanent damage by reducing power first, then going to Turtle mode, then shutting the car down. EDIT: applying high load to the pack from the motor will raise these imbalances, because the weak cell(s) will have a higher voltage drop or "sag" (because of their lower capacity) than the healthy cells.

LeftieBiker said:

The problem is differences in capacity between the cells, resulting in differences in voltage as they discharge. When the cells have lots of charge, those differing voltages are still close together. As the bad cells near empty, though, while the good cells stay well charged, the voltage differences increase, because discharged cells have substantially lower voltages than charged ones. Below 20% charge the imbalances start to near the trigger point for the battery management system (BMS) to sound the alarm (DTCs) and act to protect the pack from permanent damage by reducing power first, then going to Turtle mode, then shutting the car down.

Click to expand...

That makes sense. Thank you.

twilsonco said:

At this point my plan of action is to

1. replicate this issue with Leaf Spy recording (probably by heading up the mountains via freeway in the cold), and
2. also record with Leaf Spy the cell voltage behavior while charging. I'm planning on charging at 6.6kW, assuming it will better expose voltage issues than a 1.5kW trickle charge. Should I instead use a 50kW DC charger to better show voltage when charging?
3. See if I'm able to achieve a more permanent turtle mode by flooring it at low SOC, then
4. With the data, and more videos in hand, I'll then show up in turtle mode ready to lodge a complaint with the manager if they continue to assert it's just "normal battery capacity degradation".

And just to confirm my suspicion, the sources I linked to in my post showing typical temperature effects on EV range are useless in whatever case I lay out, yes?

Click to expand...

The charging step will not add to your case.
Your suspicion is correct.

Regarding documentation, keep your own clear records for sure, but also require the Nissan dealership to document your complaints to your satisfaction. The game here is not to diagnose your car for the technician -- neither the tech or Nissan is interested. The game is to document a specific complaint that they cannot weasel out of.

Hang in there ! We all fully expect you to get a 40 kWh battery by the time the fat lady sings.

By the way, while crappy LEAF techs are a dime a dozen, good ones DO exist. Do you have other choices at the same or a different dealership ?

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Forum,
I have this somewhat vague memory of a LEAF owner from San Diego who I think was a moderator. "Drees" maybe ? Or something similar. IIRC he was jerked around by Nissan corporate for over a year before he finally convinced them of a needed warranty repair. Is this jogging any memories ?