2013 Capacity loss, possibly just one cell?

[wb6otg]

A few months ago, my mother-in-law bought a 2013 LEAF with about 40k miles on it. My bluetooth dongle wasn't working at the time, so she bought it without a LEAF spy scan. (The price was low enough that it was worth it even if it was about to lose its first capacity bar)

It has seemed to have less range than our 2015 or the 2013 that we turned in at about 26k miles, and I finally got around to scanning it.
Battery SOH is 84%, Hx is 80, so that explains the range.
The odd thing is that all cells except for #3 show red, which I assume means that the balancer is drawing current from them. I observed the individual cell voltages from about 80% capacity down to 7%, and a couple of times while charging. Cell 3 is always blue and the others are always red. (voltages are fairly consistent between cells)
I assume this means that it has one weak cell and the balancers are dragging the other cells down to its level.
Does anyone know how much current the balancers draw? Could this one weak cell account for most of the capacity loss?

Bill

 

[dhanson865]

A few months ago, my mother-in-law bought a 2013 LEAF with about 40k miles on it. My bluetooth dongle wasn't working at the time, so she bought it without a LEAF spy scan. (The price was low enough that it was worth it even if it was about to lose its first capacity bar)

It has seemed to have less range than our 2015 or the 2013 that we turned in at about 26k miles, and I finally got around to scanning it.
Battery SOH is 84%, Hx is 80, so that explains the range.
The odd thing is that all cells except for #3 show red, which I assume means that the balancer is drawing current from them. I observed the individual cell voltages from about 80% capacity down to 7%, and a couple of times while charging. Cell 3 is always blue and the others are always red. (voltages are fairly consistent between cells)
I assume this means that it has one weak cell and the balancers are dragging the other cells down to its level.
Does anyone know how much current the balancers draw? Could this one weak cell account for most of the capacity loss?

Bill

Is the one blue cell a taller bar or a shorter bar than the rest?

What is the difference in mv (imbalance) at the bottom right of the leafspy screen 1?

 

[wb6otg]

The blue bar is towards the short end of the range of voltages, but is usually not the lowest. Voltage distribution was around 15mV when I checked. It does not drop more than the others on acceleration or rise above the others on regen, so the cell internal resistance seems to be ok.

 

[cwerdna]

Voltage distribution was around 15mV when I checked.

15 mV imbalance is not big at all.

 

[dhanson865]

The blue bar is towards the short end of the range of voltages, but is usually not the lowest. Voltage distribution was around 15mV when I checked. It does not drop more than the others on acceleration or rise above the others on regen, so the cell internal resistance seems to be ok.

If it isn't the tallest bar or the shortest bar it isn't bad in any way.

The red vs not red isn't significant in this case. Ignore it.

15mv spread is fine. Battery is just weak all over.

 

[wb6otg]

Am I correct in my understanding that red means the balancer is drawing current from that cell?

 

[dhanson865]

Am I correct in my understanding that red means the balancer is drawing current from that cell?

Each bar is for a pair of cells. The bar turning red means power is being shifted from one cell in that pair to the other. It isn't draining down, it's evening out. While some amount of power is wasted in the transfer it's almost immeasurably small. Not an issue for range.

 

[LeftieBiker]

Is the car set for 80% charge limit? If so, or if it hasn't been charged to 100% lately, try doing that, leaving it plugged in until all the charge lights go out and stay off.

 

[knightmb]

Is the car set for 80% charge limit? If so, or if it hasn't been charged to 100% lately, try doing that, leaving it plugged in until all the charge lights go out and stay off.

I was going to mention the same thing, if the car has been sitting for a while, you'll need to exercise a the battery a little if it is set for 80% charge range instead of 100%. At 84% SOH, has it already lost one bar?

It was also mentioned that the range was less, how much less than what you are accustomed to? There are many tips and tricks to maximize range if that is what is needed the most vs. just normal in town car utility.

 

[wb6otg]

I've been charging to 100% and leaving it connected until the lights go out.

I was wondering how it could be at 84% SOH and not have dropped a bar and then it lost a bar yesterday afternoon.

I've had a LEAF for over three years now (first a 2013 and now a 2015), so I'm reasonably aware of driving styles that reduce or extend range. I've been driving this LEAF for a couple of weeks while my mother-in-law is out of town, so it's basically a side by side comparison of it and my 2015.
She is quite happy with the car, since her longest drive is something like 30 miles, with the usual being less than 5. I'm just trying to understand what's going on.

Thanks for the help. Finding out that the balancer moves energy from one cell to another instead of draining energy was a big step in understanding.