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30KW Tekna (2017)
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Discussion Starter #1
So since my cell replacement I was told to give it a good balance.

just wondering how many days to charge to 100% to fully balance?

I have done 2 full charges now? Does anyone have experience on how many full charges it took to get to a point where your pack was as well balanced as it’s every going to be?
 

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A good balance would show that cells are as close to each other as possible.

The min / average/ max cell voltage will be close. Max duff will be low as well. My Leaf30 when balanced has a different of 11mV

Sent from my SM-G973F using Tapatalk
 

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Interested to know more info on your cell replacement, like how many were replaced and what was the mV difference across the battery when you got it back.
The reason I ask is I had 4 cells replaced when it came back it had a delta of 50mV, I questioned this at the time and was told that by normal usage and charging the battery would balance and the mV delta would come down, it never has, I am told that the reason for this is that the shunts built into the battery are so small they cannot balance properly if the delta is to high.
I think what this means is the car would have to be left in drive mode for an incredibly long time in order for the miniscule shunts to equalise the individual cells to within say 20mV , during normal usage (driving charging etc) the shunts will never be able to balance the battery if it is beyond a certain delta.
I think the max acceptible is 30mV, above this like mine at 50mV the BMS will not balance it.
 

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Discussion Starter #4
A good balance would show that cells are as close to each other as possible.

The min / average/ max cell voltage will be close. Max duff will be low as well. My Leaf30 when balanced has a different of 11mV

Sent from my SM-G973F using Tapatalk
Thanks Dave, I was just wondering how long it has taken people to get to a relatively flat view in LeafSpy.

Interested to know more info on your cell replacement, like how many were replaced and what was the mV difference across the battery when you got it back.
The reason I ask is I had 4 cells replaced when it came back it had a delta of 50mV, I questioned this at the time and was told that by normal usage and charging the battery would balance and the mV delta would come down, it never has, I am told that the reason for this is that the shunts built into the battery are so small they cannot balance properly if the delta is to high.
I think what this means is the car would have to be left in drive mode for an incredibly long time in order for the miniscule shunts to equalise the individual cells to within say 20mV , during normal usage (driving charging etc) the shunts will never be able to balance the battery if it is beyond a certain delta.
I think the max acceptible is 30mV, above this like mine at 50mV the BMS will not balance it.
I had a range of about 60-70 miles driving like a nun, and a differential of about 87-97 when charged.

They replaced 2 weak cells as a result of my LeafSpy findings and I now have a cell delta of 18mV.

My range has shot up, I can now do an easy 100 miles without really trying (got 112 to LBW) and my LeafSpy soc is nearer the leafs one, I basically had about 30 miles stuck in my battery I could not access which I now can.

Unfortunatly my SOH is still about 87 so that’s disappointing and my capacity at 100% is only 25.5kw, 329 gids and have an Hx of 74.19, so not the best battery in the world unfortunatly.
 

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Thats really similar to what mine was doing except mine is a 24.
But it looks like whoever did yours did a better job of pre charging your replacement cells than the person who pre charged mine.
Like you I had a big chunk of battery still in the battery that was not useable and eventually the car failed to start and through up several errors.
As for my battery condition at the last 100% charge soh was 93.7% 266 Gids Hx 92.1% so my capacity is approx 21.2kW.
 

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Is balancing done all the time you are in Drive, or does it only occur in the hour after reaching 100% SOC before the car terminates the charging? [I have found that I get a longer distance traveled per %SOC when I charge to 100% than when I only charge to 80%].
 

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Discussion Starter #7
Is balancing done all the time you are in Drive, or does it only occur in the hour after reaching 100% SOC before the car terminates the charging? [I have found that I get a longer distance traveled per %SOC when I charge to 100% than when I only charge to 80%].
Its the last 96-100% that balances, you'll see it takes forever to finish that little last bit because its balancing. Once the lights go out its stopped and you'll see on your app it stops charging, so will not balance anymore.

I know a lot of people say to keep it plugged for hours once its finished charging, but I think once all the lights are out and it says its finished charging its balanced all it can for that charging episode.

What I do want to know it how many successive charges to 100% it takes to get optimal balancing, I want to get mine as good as I can, but have no idea if its as good as its gonna get after 1 balance, or if I have to keep charging to full for a week or two.
 

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I was under the impression that the shunts are active all the time the car is either charging or ready to drive , hence why when using leafspy some cells show red and some blue, the red cells are being actively shunted ie discharged to balance with the blue cells.

I also think the last part of the battery charging cycle takes a while because
1. it is nearly full and only drawing a low amperage and
2. by design to allow a decent amount of time for the battery shunts to balance the cells as much as possiblein the time given.

Having said that I refer to my previous post where I stated that if the battery delta is far enough out the shunts can never do their job effectively.
I have tried all sorts to balance mine over the last 9-10 months but to no avail
!
 
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