Repackr dot com Vs Capacity cells sorting


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507PowerWall

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Jun 6, 2020
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103
Hi All,

I have been reading that each parallel should have cells within 50 to 100mAh

But in Repackr.com when I usi it, give me in each parallel block on top 2600 and the bottom of the "p" 1800mah ones....

Can you please clarify what im missing :(


Thanks!
 

Korishan

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Perhaps do a screen capture of what you are seeing and highly what you mean.

From what I understand, the rePackr will show the cells in numerical order from highest capacity to the lowest for each parallel group.
 

507PowerWall

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Korishan

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Capacity is individual cells listed. It doesn't matter what order you paste them in.

When rePackr spits out the results, the capacity is total capacity for each "parallel" block
 

stevelectric

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Nov 2, 2018
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45
507PowerWall said:
I have been reading that each parallel should have cells within 50 to 100mAh

Never heard of such a thing . The goal of sorting is to make each parallel have the same capacity, this means the sum of all cells. Both methods achieve that by optimally mixing stronger an weaker cells.
 

daromer

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Oct 8, 2016
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Same capacity in each pack
same amount of cells in each pack
same amount of low capacity cells in each pack
same amount of high capacity in each pack.

This is VERY easily done without repackr.
 

507PowerWall

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Jun 6, 2020
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Guy Thanks!, thanks for open my eyes.... still harvesting laptop batteries ... looking for a 14s100p, Thanks again!
 

UncleZeb

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Nov 10, 2020
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daromer said:
Same capacity in each pack
same amount of cells in each pack
same amount of low capacity cells in each pack
same amount of high capacity in each pack.

This is VERY easily done without repackr.

Same model/manufacturer ? On a scale of 1->10, how important ?
Same discharge current ? On a scale of 1->10, how important ?
 

daromer

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Depends on your application. If its lower than lets say testing current of max 0.5-1A its more important.
There is no way i want to scale that because noone have done any testing in a sense that its worthy to scale it.

Of course the more equal a pack is the better. Best is to use new cells
Lets say
Old cells = 1
new cells = 10.

There you have your scale ;)
 

OffGridInTheCity

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Dec 15, 2018
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2,032
I've deployed 84 packs (6 batteries of 14s)of 88p to 120p so far - e.g. 260ah/pack is the design.

I've found that it's best if a 'battery' (e.g. a 14s unit) is made up of thesame cell types orequally distributed counts/capacityof compatible discharge curve cells. For example, grey LGABB41865(s) play nicely with NCR18650A(s) and I have a battery that is 50% of each. The cells in all my packs add up to261ah - 263ah at initial construction.

Once deployed, about 10% of these packs needed 'adjustment' to be more perfectly balanced. I added between 3 and 6 cells to about 10% of the 'weak' packs and wa la, a set of 84 packs that run for 5 months with no balancingin the 50% DOD range. After 5 months the normal low of40mv max difference and high of 60mv max differenthad drifted up to 80mv max difference - so I did a Batrium auto-level balance for a few days and its right back down to 40mv to 60mv max difference for the last month and counting.....

Some things I learned:
1) Healthy packs need very little balancing.
2) If you leave room in your pack design - you can 'touch up' a pack by adding (or even subtracting) a few cells - to fine tune things. Patience is good as it can take several days of charge/discharge/balancingto fine tune things.
3) Stick with better cells - all minewere 85% of original capacity and good IR
4) All cells grouped by 100mah capacities - and evenly distributed among the 14s packs of a 'battery'. For example, if a 14s100p = 1,400cells... and you have 140cells at 3000mah, 140cells at 2900mah, 140cells at 2800mah, .... etc - then each pack would have 10 x 3000mah cells + 10 x 2900mah cells + .. etc. Just round robin the different capacities thru the 14 packs so they are evenly distributed AND add up to same ah per pack.
5) Don't overload (discharge) more than you test OR more than the cells are designed for - you may get unacceptable voltage drop and if so, that's hard on the cells as well. For example, I use 500ma discharge testing... and my powerwall averages 300ma discharge/cell... all is good. On the other hand, I did some APC 7s7p packs and found that 'laptop' cells really don't like 2a/cell discharge- thevoltage dropped significantly as the load hitand thendegraded prematurely to cut-off within minutes - way faster than it should'per calculatedcapacity. Don't be surprised if you fail toget useable max discharge amps thatyou might readabout for your specificcellunless you actually test for it :)
 

UncleZeb

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Nov 10, 2020
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Makes perfect sense ... really appreciate those expert explanations/recommendations. Thanks muchly :heart:
 
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