wina exit strategy

ltosolini

100 mW
Joined
Apr 17, 2016
Messages
48
I had a lousy experience with Wina 50ah in 20S configuration on my electric scooter as from my previous post: https://endless-sphere.com/forums/viewtopic.php?f=14&t=83669
Given also other negative feedback collected on the net, I have decided to abandon this brand and replace it with Winston 40ah prismatic which has more or less same size.
But I don't want to throw away all the Wina cells right away, I would prefer to use their residual capacity; so I was thinking of the following substitution plan:
- I will replace immediately the 4 wina cells which are almost dead and run on 16x wina + 4x Winston
- gradually replace wina cells individually as they are close to death
- finally reach an 20S target based solely on Winston
The rational behind this approach being:
- first of all, not to throw away cells with residual capacity, which makes me fell bad
- when there is a mixed pack, the wina will be always be the weakest link while Winston will be the strong one; so it will be the wina to suffer for deepest discharge and wider cycle while Winston will have easy cycle; therefore the new Winston cells will not suffer in the mixed usage.
I forgot to tell that I have a very efficient balance charger that will be able to balance charge the pack even in condition of huge disalignement.
What do you think of this approach?
Thanks!
 
Makes sense to me.

What I'd like in the same situation would be a way to easily check voltages of each cell. This way you can identify which cell is the weakest at all times, and keep an eye on that cell to know when to stop for charging.
 
I must make late justice to Wina cell and take my share of responsibility.
I have opened the scooter and removed the cells; i found out the following enlightening result.
Out of 20 wina 50Ah cells:
- 8 cells that were housed in low compartment, reaching to half the size of the cell, are swollen in the higher half of the cell and capacity degraded to as low as 11AH
- the remaining of the cells housed in higher compartment reaching the the entire height of the cell, are in perfect shape and still full capacity; I did a discharge test getting figures as high as 52Ah!!
My kudos to Wina and shame on me for poorly housing those cells.
Lesson learned: the cells must be contained with uniform pressure on the side!!
This was a bitter and expensive lessons learned: 8 cells to throw away :-(

Now, considering that at least 10 cells are as good as new, I am still considering sticking to Wina 50Ah rather then Winston or Sinopoly 40Ah; it makes a big difference 10Ah+.
 
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