Battery max mV sudden increase

[Marktm]

I captured this battery screen on LeafSpy - never seen anywhere close to this delta mV. After charging it has gone back to the 20-30 mV range that is normal - even at low SOC's. The battery is a year old with 10,000 miles on it.

IMG_5639.PNG

Shocked me, however, I've always been suspect that the cell numbers in the 70's and 80's were not well matched in this "new" Lizard battery. The Ahrs seem to be dropping more rapidly in the last two months also.

Any comments/suggestions?

[Nubo]

I'd probably drain it close to zero and do a full charge, repeat that for a couple of days, and then take a look at the balance at the 16% SOC level for comparison.

[DaveinOlyWA]

I see this occasionally when SOC is low. Usually in the 30-50 mV range at that SOC but occasionally in the 100+ range although generally on SOC < 10%

[Marktm]

I recall that there was a OP that had a bad cell and that he eventually was able to obtain warranty work on a defective battery (I believe it was under the 10 year warranty?). I'm concerned that I should be initiating some record of suspect battery voltages - maybe with a local dealer. If the situation worsens or the high delta mV's cause even more rapid degradation, it seems reasonable to alert Nissan. However, if this extremely high delta mV is just some "normal/fleeting" point in time, I don't want to "cry wolf". I realize any LeafSpy chart has no validity to Nissan - I wonder if the "logging" done by Nissan's firmware/software has similar resolution that Nissan can actually see similar high mV excursions at times? If I recall, there is a DTC that is thrown if the mV's exceed a certain level?

[GerryAZ]

I routinely see that much or more delta mV when my 2015 is down into VLBW. In fact my car is charging right now. It was at 7 Gids when I parked with the following stats: AHr=46.68; SOH=75.17%; Hx=53.65%; V=347.06; ODO=50,402; QC=106; L1/L2=824; min. Cell=3.560V; avg=3.615V; max cell=3.679V; delta=119mV. Battery temperatures were 88.8, 87.4, and 84.4 degrees F with 6 temperature bars displayed. And yes, I recently lost my second capacity bar. Battery voltage at full charge is typically 394.5 to 395.5 with a cell voltage delta of 9 to 11 mV.

Based upon the stats I routinely see, I would not worry about your battery unless the cell voltage delta gets a lot higher. Another thing I notice with my car is that internal battery resistance and cell voltage delta drops for a while after quick charging so you could do a QC or two if you have access to quick chargers.

[DaveinOlyWA]

I recall that there was a OP that had a bad cell and that he eventually was able to obtain warranty work on a defective battery (I believe it was under the 10 year warranty?). I'm concerned that I should be initiating some record of suspect battery voltages - maybe with a local dealer. If the situation worsens or the high delta mV's cause even more rapid degradation, it seems reasonable to alert Nissan. However, if this extremely high delta mV is just some "normal/fleeting" point in time, I don't want to "cry wolf". I realize any LeafSpy chart has no validity to Nissan - I wonder if the "logging" done by Nissan's firmware/software has similar resolution that Nissan can actually see similar high mV excursions at times? If I recall, there is a DTC that is thrown if the mV's exceed a certain level?

a bad cell will standout with SOC as high as 70%. In a normal pack, deltas are normally 10-50 mV from full to under 20-30% SOC.

a bad cell will have deltas approaching and exceeding 100 mV at relatively high SOCs. I would imagine that the very earliest signs of cell failures may not be noticeable until the SOC is lower but still the difference will easily be 2-3X any other "good" cell

[Marktm]

After studying the 2012 EVB manual, specifically P33E6 logic for diagnostics/repairs (pg 138-141 - at least for my 2012), this seems to be the logic:
1. DTC P33E6 must be Registered -otherwise no further action is required
2. DTC's P0A1F,P3062 in conjuction with P33E6 is a battery controller issue
3. DTC P33ED in conjuction with P33E6 is a "battery parallel diagnostic"??
4. Otherwise the "cell voltage deviation diagnostic" procedure is followed.
5. The various procedures that followed seem quite convoluted/unclear logic, however, it is clear that the 3.712 mV is only used as the required value to discharge the minimum voltage cell (via consult) to below the 3.712 threshold before further testing with Consult - don't believe it has any other significance as the battery is simply discharged by turning on all big users until the minimum cell is 3.712 mv or below.
6. There are many steps that follow using Consult to confirm the cell/module to be replaced AND to check all other internal battery components - I'd guess to ensure against any false Consult results and/or weak/damaged hardware components.
7. Replacement of the bad module and any faulty wiring/hardware. Interesting that if there is evidence of "condensate", the battery is simply replaced - no further explanation. I'm not sure of the logic because it seems the modules are replaced on two separate parts of the procedures - that makes no sense.

Maybe someone that has used Consult to do an actual module replacement can explain the actual logic flow of steps 2-10! It could also be that the later model year procedures have been revised? Maybe I missed something.

Bottom line to me is that unless you have "thrown" DTC P33E6, there is no bad cell replacement under the manufacturer's warranty against any defects.