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Discussion Starter · #1 ·
I noticed some time ago when using LEAFSpy that the cell voltages under certain conditions appeared to have a peculiar shape, with three "humps". It was difficult to capture while driving as it only appeared under moderate battery load. Say accellerating on the motorway. Sat stationary the voltages would flatten out. But i did manage to get these screenshots nearer the start of June:

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The 55% SOC one was sitting on the motorway at speed, but on an uphill section that requires a decent chunk of power. The 93% one was full throttle accelleration having joined a dual carraigeway.

I kinda forgot about it, but the other day driving home i ended up running the car down to very low SOC. This was after about 5 miles of driving with both % and mileage showing ---, and the other screen showed 8 GID's left.

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Now i understand the huge spread is exacerbated by the very low SOC, but clearly this indicates that some of these cells are in poorer condition than others. The bit i cant quite figure out, is whats causing the peculiar shape? Its not one bad cell, its half the pack, and in a defined pattern...

@Dalathegreat Seen anything like this before?

Fully charged, the cells all sit with <10mv spread, and even when the SOC is fairly low, so long as theres not any load on the battery they tend to show a very small spread. I'll try and get some screenshots of low SOC but no load.
 

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The voltage drop under load for some of the cells compared with when not under load implies that they have a higher internal resistance. Is it that these cells are colder (because they are towards the front of the battery pack)? While the first two charts give the readings of the battery thermometers, your final one does not.
 

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Discussion Starter · #3 ·
Looking at the cell numbers, the bottom of the curve on the left side is the middle of the rear stack. So if anything they'll be hottest.
 

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Leaf 30kWh, HS PHEV
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IMO cells 5-45 display lower voltages and have likely lost capacity compared to the others. 4 in the group with cell 25 in particular.

When not under load, voltage tends to level out - characteristic of Li-ion cells


Sent from my iPhone using Tapatalk
 
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