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

[nlspace]

Yes that is how i understand the meaning--below 5V for a module is outside of the allowable range and the mechanic is instructed to replace the module.

In nearly every DTC related to the cells or pack, the troubleshooting instructions call out to drain the pack down to 1 segment, then charge the pack back up to full, then use the Consult tool to read for any DTCs and read the Freeze Frame Data that is also stored when the DTC is set. Depending upon the code the common solution seems to be either replace the LBC or a module.

e.g. P33E6 covers when the difference in max and min cell voltage is outside the allowable range. After the drain/charge cycle, calculate and compare these values, [A=max-average] and (B=min-average). If A>B then replace the module with the high cell; If B>A then replace the module with the low cell.

P33ED is called Battery Parallel Diagnostic, but is set when there is seen a sudden voltage fluctuation in a module. No real technical insight in the FSM, just find the malfunctioning cell and replace the module.

 

[MikeinPA]

Yes that is how i understand the meaning--below 5V for a module is outside of the allowable range and the mechanic is instructed to replace the module.

In nearly every DTC related to the cells or pack, the troubleshooting instructions call out to drain the pack down to 1 segment, then charge the pack back up to full, then use the Consult tool to read for any DTCs and read the Freeze Frame Data that is also stored when the DTC is set. Depending upon the code the common solution seems to be either replace the LBC or a module.

e.g. P33E6 covers when the difference in max and min cell voltage is outside the allowable range. After the drain/charge cycle, calculate and compare these values, [A=max-average] and (B=min-average). If A>B then replace the module with the high cell; If B>A then replace the module with the low cell.

P33ED is called Battery Parallel Diagnostic, but is set when there is seen a sudden voltage fluctuation in a module. No real technical insight in the FSM, just find the malfunctioning cell and replace the module.

"sudden voltage fluctuation in a module." No. Edit: not relevant to diagnosing OP's battery problems

"[A=max-average] and (B=min-average). If A>B then replace the module with the high cell; If B>A then replace the module with the low cell."
Reference?
" troubleshooting instructions call out to drain the pack down to 1 segment, then charge the pack back up to full" Reference?

 

[nlspace]

This information is all found in the FSM for the EVB, i think you were the one to post the link to that manual.

In a .pdf file to quickly find something i like to use the search feature, press control and "f" at the same time to open a box, then type in the word and press return. e.g. type in "P33E6", the DTC you want.

Another method is to look it up in the table of contents, the DTCs are listed in numerical order. All the FSMs seem to be organized in a similar manner.

 

[SageBrush]

... use the Consult tool to read for any DTCs and read the Freeze Frame Data that is also stored when the DTC is set.

If OP gets the chance I hope he avails himself of the freeze frame data and shares it here. That seems the way to learn the DTC trigger conditions

 

[MikeinPA]

This information is all found in the FSM for the EVB, i think you were the one to post the link to that manual.

In a .pdf file to quickly find something i like to use the search feature, press control and "f" at the same time to open a box, then type in the word and press return. e.g. type in "P33E6", the DTC you want.

Another method is to look it up in the table of contents, the DTCs are listed in numerical order. All the FSMs seem to be organized in a similar manner.

I plugged pieces of the text you provided into the search function in Acrobat and was unable to find the text you have provided in the manual. If you could use the page numbers to assist me, please do.

 

[SageBrush]

" troubleshooting instructions call out to drain the pack down to 1 segment, then charge the pack back up to full" Reference?

EVB-192

I read the PDF inside my Chrome browser. I'm able to search (CMD-F on a Mac) for 'EVB-192' and be taken to the bottom of that section

 

[nlspace]

...
If you don't have this already, the data in the graph above was collected during Nissan's "Cell Voltage Loss Inspection", see page EVB-160 of the 2013 Leaf EVB manual, here: https://ownersmanuals2.com/d/43004

You're kidding me right? The diagnostics for DTC P33E6 begins on EVB-160

 

[SageBrush]

Yes that is how i understand the meaning--below 5V for a module is outside of the allowable range and the mechanic is instructed to replace the module.

I'm having trouble with the cell arithmetic

Nissan says
https://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/li_ion_ev.html#:~:text=In%20the%20first%20LEAF%20(equipped,modules%20on%2Dboard%20the%20vehicle.

4 cells per module, 24 modules per 24 kWh pack, so all cells are in series to reach 96S. To reach 5V, each cell in the module has to average 1.25V. I think that is way past dead.

What am I missing here ?

 

[LeftieBiker]

It sounds to me like Nissan is using the term "module" for "cell." Since the cells are packed in pairs in modules, this is unfortunate. OTOH, 5 volts is way too high for a lithium cell - it should be more like 4.2. 5 volts is indeed an Odd number...

 

[goldbrick]

Isn't each module 2S/2P configuration ? So 5V on a module would mean 2.5V on an individual cell which is fairly low for Li battery IIRC.

 

[twilsonco]

I got my car back from the dealer and was able to reproduce the issue once. As I mentioned in the OP, this is reproducible in ambient temperatures of 30°F and lower. It's now warmed back up until next weekend, at which point I'll be able to do more testing and try to raise some DTCs.

Because I didn't think to record my screen, and I'm interested in visualizing the car behavior over time, I'm working with log data. Below are two cluster plots, the first is a 3-minute stretch of data where I reproduce the issue and invoke turtle mode, and the second a ~13 minute quick-charge session starting at a low SOC. Forgive the nonsensical figure numbering.

The left column of plots are various bits of data plotted vs time; the title, legend, and lines with color-corresponding axes should make them fairly easy to read.
The right column has at top, the cell min, max, and time average voltages over the duration of the time plots, and below are cell voltage bar charts and histograms at significant times in the data corresponding to max/min cell voltage differences.

No DTCs were thrown during the plotted times, nor were any "Judgement" values calculated.

Turtle mode plot cluster

Here, I'm driving down a stretch of 65MPH highway, from east to west as shown in the map. The orange-shaded stretch (roughly) is up a moderate hill (also shaded in Fig 3). As I go up the hill, and apply 100% throttle, the cell voltage difference starts to climb, and peaks at about 800mV difference at 1.5 minutes. Turtle mode comes on at this point (red vertical line in Fig 4), and you can see the motor power drop at this point, though I'm still applying 100% throttle.

See in Fig 6 that the max cell voltage difference corresponds to a drop of the lowest cell to 2V, which is ridiculously low, but this low voltage isn't an outlier, and the average cell voltage line is nearly halfway between the min and max voltage difference lines. This can be seen as well in the three pairs of bar charts and histograms corresponding to the min and max cell voltage difference time points (blue and green shaded lines in Fig 3 respectively). The center (green shaded) cell voltage histogram that corresponds to the max voltage difference shows that the voltage difference is spread somewhat evenly across the cells. I suppose you could list bad cells in order of lowest voltage (those close to 2V).

I can't believe this didn't throw a DTC, but perhaps the quick-charge plots below will make more sense of this.

Quick-charge from 7% charge plot cluster

This one's simpler, and same plots as above. I drove around to get to where the car was reporting 7% remaining charge.

Time 0 to ~6 minutes I had been intending to follow the instructions for a cell voltage loss inspection (on EVB-161), but the dealer put my dashboard back incorrectly such that I wasn't able to set it to full heat. Regardless, during this time the max cell voltage difference was around 35mV, and I didn't see the dropoff in voltage from one or more clearly "bad" cells that I had expected to see; they all drop together.

Likewise, during quick-charging the max cell voltage difference increses from ~25mV at idle, smoothly ramping up to a peak of ~45mV. The car never charged faster than 30kW, (though it was a 50kW charger and I expected a full 50kW based on the below plot from https://support.fastned.nl/hc/en-gb/articles/204784998-Charging-with-a-Nissan-Leaf-e-or-e-NV200). The charge starts throttling at about the 10 minute mark, which is at a SOC of ~25% which is where the below plot anticipates it should. This results in the corresponding decrease in cell voltage difference, though I suspect that had the charge not throttled the cell voltage would have continued to climb.

In Fig 2 you can see that the same culprit cells from the tutle-mode case are responsible for the lowest of the low voltage values, however here they don't achieve anywhere near the same voltage difference.

Why no DTCs?

I'll hazard a guess that voltage imbalance DTCs don't throw under high-load, and instead require a rather more smooth and controlled set of conditions such that those described on EVB-161.

 

[nlspace]

Isn't each module 2S/2P configuration ? So 5V on a module would mean 2.5V on an individual cell which is fairly low for Li battery IIRC.

goldbrick for the win! This is the module configuration. Believe it or not, Nissan FSM actually calls individual cells a "cell" and the 2S2P cell units a "module".

Lithium cells can become unstable if discharged below 2.5V and then recharged, which is why some sort of cell management circuitry is found in every product that recharges lithium cells.

 

[LeftieBiker]

Isn't each module 2S/2P configuration ? So 5V on a module would mean 2.5V on an individual cell which is fairly low for Li battery IIRC.

It is, so that replaces a too-high number with a too-low one...

EDIT: so the 2.5 volts per cell is the low cutoff voltage. That makes more sense. So Nissan deals with modules the way they should deal with cells, because a good cell in a module will mask a marginal cell paired with it. This is, I'm guessing, the issue the OP has: a failing cell in the same module as a good one.

 

[SageBrush]

Isn't each module 2S/2P configuration ? So 5V on a module would mean 2.5V on an individual cell which is fairly low for Li battery IIRC.

Talking about the 24 kWh pack,
We know there are 96 serial elements
And Nissan says 24 modules and 4 cells per module. 24*4 = 96

So is it actually 8 cells per module and 4 serial elements ?

 

[SageBrush]

Why no DTCs?

I'm just guessing here, it is because you have multiple cells that are weak.
I can understand a Nissan POV that says you do not have a defective pack, you have a degraded pack.
OTOH, a pack that goes into TURTLE mode from trying to merge on to a motorway at a SoC of 30% is Nissan's problem, whether a DTC is thrown or not.

 

[nlspace]

Read up on the Fail-Safe section of the FSM; there are 4 modes A thru D, and mode C results in reduces power and limited charging, which appears to be your symptoms. There are only 2 DTCs that are mode C, the two that i identified earlier, P33E6 and P33ED.

For P33E6, the DTC can be thrown but it does not illuminate the HV error lamp in the dash because it is a F-S code. Notice the conditions for this DTC:

With the power switch ON and no load condition, the difference between the maximum voltage and minimum voltage exceeds the allowable range.

So not when it is being driven at full throttle.


The best chart worth anything is the one showing the cell voltages collapsing under high load, but they seem to quickly recover. This is how worn out cells behave. Failed cells don't recover.

The pack was down to 243 V. If it had dropped below 240, then i think a HV lamp would light up for a different DTC related to pack voltage out of range.

 

[LeftieBiker]

So is it actually 8 cells per module and 4 serial elements ?

Two cells per module. My Vectrix has 18 modules and fully charged the pack is about 144 volts, with the modules charged to about 8 volts each. (No BMS, BTW.)

 

[twilsonco]

OTOH, a pack that goes into TURTLE mode from trying to merge on to a motorway at a SoC of 30% is Nissan's problem, whether a DTC is thrown or not.

I agree, it seems like more than simply capacity degradation. There's degradation in several cells resulting in such high resistance that the car "fails" to perform a typical and expected function. Then again, the cells are still rather close in voltage under no load.

I understand that's different from a "failed" cell that's permanently failed under all conditions. And I suppose that the "failure" to perform a task is a clear distinction from a "failed" part.

I have three months left under the 8-year battery warranty. Wonder if I can expect sufficient worsening of this condition in order to gain coverage?

 

[twilsonco]

Read up on the Fail-Safe section of the FSM;
...
The pack was down to 243 V. If it had dropped below 240, then i think a HV lamp would light up for a different DTC related to pack voltage out of range.

I'll read up on that; thanks.

Wonder if the pack voltage out of range is sufficient cause for warranty coverage, or if that too needs to be when not under load.

Next weekend when I have more low temps I'll be able to reproduce this issue at a variety of loads, and probably get the pack voltage out of range DTC.

 

[SageBrush]

I have three months left under the 8-year battery warranty. Wonder if I can expect sufficient worsening of this condition in order to gain coverage?

Perhaps, but I am not optimistic due to the number of failing cells.

In your shoes I would document the unsafe performance with a dealership tech along for the ride and then complain to the regulatory authorities if Nissan remains blind, deaf, and stupid.

By the way, your documentation skills and understanding are coming along really nicely. I lot quicker than I could manage, that is for sure. I think a video screen capture of TURTLE MODE is a fine idea.