Gid Vs SOC and Cell Balance Issue

Vaggeto said:

Stanton said:

Nubo said:

Do you use an end-timer? I'm not sure if that allows a full cell-balance, especially if you use the car shortly after the end-time. Maybe someone else can clarify.

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That is a good point and basically true: if you really want to give the pack a chance to balance, you need to charge to 100% without a timer and sit for several hours (I think as many as 6).

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Does this apply even though I use both a start and end time? My Leaf always charges instantly at 8PM and never waits to finish charging by a specific end time. It usually sits around 8-9 hours at a full charge before being driven.

Thanks,
John

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My understanding is: yes, you need to run a 100% charge cycle without timers (use the bypass button). And let it set. Of course, there's no guarantee it will balance, but these are the necessary conditions to allow it.

Stanton said:

Vaggeto said:

Stanton said:

That is a good point and basically true: if you really want to give the pack a chance to balance, you need to charge to 100% without a timer and sit for several hours (I think as many as 6).

Click to expand...

Does this apply even though I use both a start and end time? My Leaf always charges instantly at 8PM and never waits to finish charging by a specific end time. It usually sits around 8-9 hours at a full charge before being driven.

Thanks,
John

Click to expand...

My understanding is: yes, you need to run a 100% charge cycle without timers (use the bypass button). And let it set. Of course, there's no guarantee it will balance, but these are the necessary conditions to allow it.

Click to expand...

John's start and end timer settings for his free power window are certainly sufficient to allow Leaf's LBC and onboard charger to charge to 100% and to balance the cells. I have start and end timers set for 9:10 pm to 8:50 am (9:00 pm to 9:00 am with 10 minutes to allow for differences between Leaf's clock and meter's clock) for off-peak charging, but usually plug in after 9:10 pm and unplug before 7:00 am. My car usually finishes charging (from very low battery warning) in 4 hours including cell balancing so John's car has plenty of time for cell balancing. The Leaf Spy screen shots clearly indicate he has a couple of somewhat weak cell pairs. They will likely get worse as time goes on.

Gerry

GerryAZ said:

The Leaf Spy screen shots clearly indicate he has a couple of somewhat weak cell pairs. They will likely get worse as time goes on.

Gerry

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They could improve.

My first CVLI via LEAF Spy Pro at about two and a half years old and two capacity bars lost had eight cell pairs showing weak.

After quite a bit of deep discharge down to high voltage disconnect and then recharging to 100% most went away.
And that was before Jim revised LEAF Spy Pro to require a much bigger error than the original 2011 manual CVLI test procedure.

The eight are still usually the weakest cells, but with deep discharge and rebalancing they now stay much closer.

Given the accessible capacity of the pack is limited by the weakest cell (pair) I wonder how much range is lost if there are obvious outliers, even if they only pop up below the LBW.

Vaggeto said:

DaveinOlyWA said:

run it down to around 80% and post a screen shot

Click to expand...

Alright... you can find a new series of screenshots at the link below.

http://imgur.com/a/O70cG

I started at ~75% and then another at about 45% and then took some others as I got lower all the way until I turtled.

The variance looked until half full but then it really started to grow. I also got one at exactly 3.712.

Do these provide any other insight? it's interesting that at about 11.7% it highlights the weak cells but at 3.9% turtle it says all cells are okay.

Do these provide any other insight?

Thanks again for your time and knowledge. It's appreciated!

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your variances are looking pretty normal here. did you take these screen shots

right after driving?

while driving?

several hours after driving?

DaveinOlyWA said:

Vaggeto said:

DaveinOlyWA said:

run it down to around 80% and post a screen shot

Click to expand...

Alright... you can find a new series of screenshots at the link below.

http://imgur.com/a/O70cG

I started at ~75% and then another at about 45% and then took some others as I got lower all the way until I turtled.

The variance looked until half full but then it really started to grow. I also got one at exactly 3.712.

Do these provide any other insight? it's interesting that at about 11.7% it highlights the weak cells but at 3.9% turtle it says all cells are okay.

Do these provide any other insight?

Thanks again for your time and knowledge. It's appreciated!

Click to expand...

your variances are looking pretty normal here. did you take these screen shots

right after driving?

while driving?

several hours after driving?

Click to expand...

These screenshots were primarily while driving or for the last one, right after driving.

Vaggeto said:

DaveinOlyWA said:

Vaggeto said:

Alright... you can find a new series of screenshots at the link below.

http://imgur.com/a/O70cG

I started at ~75% and then another at about 45% and then took some others as I got lower all the way until I turtled.

The variance looked until half full but then it really started to grow. I also got one at exactly 3.712.

Do these provide any other insight? it's interesting that at about 11.7% it highlights the weak cells but at 3.9% turtle it says all cells are okay.

Do these provide any other insight?

Thanks again for your time and knowledge. It's appreciated!

Click to expand...

your variances are looking pretty normal here. did you take these screen shots

right after driving?

while driving?

several hours after driving?

Click to expand...

These screenshots were primarily while driving or for the last one, right after driving.

Click to expand...

well then, I have to say your pack appears to be in fairly good shape. my delta stays under 20-25 mV until I hit the teens on SOC. This is where I see wild variances quite regularly. I do see up to 400mV and more sometimes. As far as the weak cells? I would keep a close eye on them paying attention to which # cell is having the most issues. the real issue starts when you have range issues so its hard to say what I would do in your case but if it were me, I would literally have no choice but to take it in for a cell check. I need all the range I can get plus some.

DaveinOlyWA said:

well then, I have to say your pack appears to be in fairly good shape.

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Speaking of which, does anyone know how the SOH is calculated exactly? My pack seems to give delta of 6mV after balancing and overall stays looking very nice under all conditions. Yet the SOH is reading is 87% and I'm not sure I see any considerable difference in range to new. Car is 2012 SL with 35 000km in it.

jmk said:

DaveinOlyWA said:

well then, I have to say your pack appears to be in fairly good shape.

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Speaking of which, does anyone know how the SOH is calculated exactly? My pack seems to give delta of 6mV after balancing and overall stays looking very nice under all conditions. Yet the SOH is reading is 87% and I'm not sure I see any considerable difference in range to new. Car is 2012 SL with 35 000km in it.

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Nissan engineers know but they haven't told anyone outside Nissan the secret.

Even in Finland a 2012 has probably lost 13% capacity just due to time.

TimLee said:

Nissan engineers know but they haven't told anyone outside Nissan the secret.

Even in Finland a 2012 has probably lost 13% capacity just due to time.

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Maybe, but I hear funny stories from people here that say how SOH keeps changing. Some say 91% reading jumped to 99% after balancing and quick charging. Also in my case I can't really confirm any actual capacity loss, car goes quite happily 150km on single charge and I'm not sure it has ever done any more than that. Drive very very carefully and I think that 160-170km is doable. Yet 13% should be noticeable already..

Vaggeto said:

DaveinOlyWA said:

run it down to around 80% and post a screen shot

Click to expand...

Alright... you can find a new series of screenshots at the link below.

http://imgur.com/a/O70cG

I started at ~75% and then another at about 45% and then took some others as I got lower all the way until I turtled.

The variance looked until half full but then it really started to grow. I also got one at exactly 3.712.

Do these provide any other insight? it's interesting that at about 11.7% it highlights the weak cells but at 3.9% turtle it says all cells are okay.

Do these provide any other insight?

Thanks again for your time and knowledge. It's appreciated!

Click to expand...

These screenshots show hat SOH means squat... how can this battery pack be at 99-100% SOH ?

Vaggeto said:

DaveinOlyWA said:

Vaggeto said:

Alright... you can find a new series of screenshots at the link below.

http://imgur.com/a/O70cG

I started at ~75% and then another at about 45% and then took some others as I got lower all the way until I turtled.

The variance looked until half full but then it really started to grow. I also got one at exactly 3.712.

Do these provide any other insight? it's interesting that at about 11.7% it highlights the weak cells but at 3.9% turtle it says all cells are okay.

Do these provide any other insight?

Thanks again for your time and knowledge. It's appreciated!

Click to expand...

your variances are looking pretty normal here. did you take these screen shots

right after driving?

while driving?

several hours after driving?

Click to expand...

These screenshots were primarily while driving or for the last one, right after driving.

Click to expand...

Taking these while driving does account for a bad cell warning verses the last one that does not flag any cells because you are not moving.

It would be interesting (and time consuming) to take shot immediately after driving and one say 30 mins later to see how much if any equalization happens.