I am going to re-iterate that it looks like you might have a couple slightly weak cells, but nothing I would call defective. This test really shows the car is running fairly well and the BMS is balancing out the differences. My 7-bar battery had significantly worse values than this, although it was a canary pack and heavily degraded.Marktm wrote:Depleted battery totally today with mix of highway, suburban, sitting with drive on. The final SOC was 2.4% with 4 GIDS. Full power was 80,000 watts right up until turtle. When turtle kicked in, the max was around 7000 watts (LeafSpy battery bar readings). At present L1 charging (for the next 12 hours of so!).
The battery values at shutdown:
Your car looks fine to me. I would not try to stress it to bring out the "defect", as I don't think you have one. You're likely to just wear out your battery more quickly.Marktm wrote:Yes, now the decisions about how to make that happen quicker vrs extending battery life - within the confines of acceptable usage and care. I believe the "defective" is 10 years. However, a replacement "Lizard" start date might be in question??
This weak cell test *should* be performed dynamically, while the car is putting out maximum power. That is where the weak cells will matter, because they will cause the car to limit power or go into turtle despite a SoC that is otherwise high enough to not trigger those conditions.Lothsahn wrote:
The first LeafSpy you linked showed an average cell voltage of 3.45V, whereas the new graph shows a voltage of 3.1V. While this sounds like a huge difference, it's actually very small for the 24 kWh cells. See the SECOND discharge curve on this page: (the top discharge curve is the new 40 kWh cells):
https://pushevs.com/2018/01/29/2018-nis ... eal-specs/
The second curve shows the voltage falloff occurs at around 3.6V (use the top light blue line, as you were presumably not driving while getting the LeafSpy screenshot, which means you should be using the 1/3C line). If you look at this graph, you can see the difference between 3.45V and 3.1V is less than 1 Ah. Each cell holds 30 Ah, so a 1Ah difference is very small.
I get that the test should be performed at maximum load, but we're talking about the state of the cells and the LeafSpy that was pulled. In that graph, it shows that the weak cells are at most 2-3% lower capacity than the rest (excluding effects from cell balancing). This is not a significant difference and it doesn't indicate a cell defect. Encouraging the owner to try to "stress out" the pack to get those cells to fail quickly likely won't work--these cells were slightly weaker, but only slightly. Furthermore, those cells were not showing low voltage again in the next LeafSpy screenshot.SageBrush wrote: This weak cell test *should* be performed dynamically, while the car is putting out maximum power. That is where the weak cells will matter, because they will cause the car to limit power or go into turtle despite a SoC that is otherwise high enough to not trigger those conditions.
We have been told in multiple threads that Nissan will not perform, or will ignore cvli results unless a specific DTC is logged. It is tempting to guess that DTC occurs when the system hobbles power output, but that would occur only if the power demand exceeds the system allowance.
Put another way, I suspect that sustained maximum power is the way to expose weak cells and log the needed DTC.
What is sustained ? I'm not sure. 30 -60 seconds sounds reasonable to me since it could be seen in mountain driving.
I would not. Turtling a battery is hard on it, as it gets the charge level quite low. Unless he starts to see evidence of an actual cell failure, you're not likely to trigger a DTC and you are stressing out the battery pack.SageBrush wrote: If I hard Mark's LEAF I would stress test it every 6 months or so, and a week before the warranty lapses.
Has anyone seen evidence that the severely degraded 2011,12,13's will start setting the DTC and fail the CVLI test as the battery reaches end of life (2,3,4,5 bars)? If so, is there any way Nissan can back away from the warranty based on the "language". I'm simply wondering if the 10 year defect warranty might offer some "opportunities" for another round of replacements?GerryAZ wrote: ↑Wed Jul 24, 2019 7:14 pmMarktm's "weak cells" are not weak enough to be of concern at this time. For example, I had 363 mV difference last night on my way home. I also see VLBW come in with pack voltage above 360 volts (indicates a lot of energy is left in stronger cells). My experience is that results of CVLI tests are quite variable. LEAF Spy Pro performs the CLVI test whenever the average cell pair voltage is low enough to meet the guidelines in the service manual and the car is in neutral or park. I sometimes see LEAF Spy list 1, 2, or more weak cells and other times see it show all cells are OK when battery SOC is near VLBW or lower. So far, it has not set DTCs and there has been no power limitation (other than risk of sudden turtle mode or shutdown if high discharge rate is sustained long enough to keep minimum cell voltage low for too long). LEAF Spy did not show weak cells when I took the car in for the annual battery test in January so I was not surprised that Nissan did not do anything under the defect warranty--will see what happens next year. Regardless of whether LEAF Spy shows weak cells by module number or not, I can see from the cell pair voltage graphs that several modules located at the front of the battery are weak (very low voltage under load and higher voltage while charging compared to other cells). I will try to post some screen shots when I get a chance.
What 10 year defect warranty? It's only 8 years/100K miles, whichever comes first.Marktm wrote: ↑Thu Aug 15, 2019 2:08 pmHas anyone seen evidence that the severely degraded 2011,12,13's will start setting the DTC and fail the CVLI test as the battery reaches end of life (2,3,4,5 bars)? If so, is there any way Nissan can back away from the warranty based on the "language". I'm simply wondering if the 10 year defect warranty might offer some "opportunities" for another round of replacements?