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2 pack faling behind with charging and get unbalanced (update 9/07/2020)
#51
(08-25-2020, 08:54 PM)barry Wrote: yes my cells are 25/26 mΩ Big Grin it took me 1,5 year to harvest all the cells (14s60p) and all the measurements were taken with a YR1030 and all from the same e-bike brand make and model (LG/SAMSUNG/PANASONIC 85% off the packs) it took me a long time to get them exept the sanyo 

@wolf  
Question: Is the cell ratio pretty much the same in all your packs? YES

Then you did everything right in my mind @barry.
With 0.006V diff I think you are very much in the ballpark. I would even say you are in the infield.
Other than the 1 cell with the odd flame-out all is well. Smile Smile

Wolf
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#52
(08-25-2020, 04:08 PM)barry Wrote: Well unbalanced pack (other pack oke now) still gets unbalanced..and falls behind (over time, two 2 days) with the rest it is not mutch but it falls behind..
I charged the pack separate of the rest i had a 20 milli head start turned ballancing off now the pack is 5 millivolt behind so a differants off 25 millivolt

You say after 2 days it goes to about 25mV diff. But is this rate continuous? What is this after a week? two weeks? one month?
So if your packs are wildly different then you have some cells that are self discharging over a longer period of time. This is bad.

My packs differ anywhere from 5-25mV a day. I don't care about it. But it never 'drifts'. I can turn off my balancer for a month and my packs will stay the same.

Also what are your min/max balancing points? Are they too high/low that it's meeting the limit of the differences in your packs? Ie. you set your bms to balance at 4.1V and you also charge to 4.1V so one pack that has a lower amp pack reaching that max first then your balancer is discharging that pack thus sucking energy out of that pack. And when it drains it will now be 'unbalanced'. The only time it reaches 'balance' is at the top end (i.e. 4.1V). This the top end balancing. This is not necessarily a problem.
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#53
a little update.. Big Grin the pack is in balance now and the diff is now 0.003 so thats pretty nice to see Cool
i think i made a mistake in sorting i swaped 4 cells with 2000 mah for 2500+ mah and the pack is following the line of all the packs i think that pack whas low in cappacity and over time it whas falling behind with the rest of the packs.
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