How to select eight out of ten cells for battery?

[carbon60]

I bought (an incredible three years ago now) 10 GFB (Ganfeng) 277 Ah cells (which should test higher), to keep on the shelf for second project: a van. I bought an extra two cells because I saw the uncertainty in the supply, and the quality, so I didn't want to end up with 7 good cells and no good way to move forward. I am about to build this 8S battery and now have them sitting on the bench to be top balanced.

How should I choose the 8 cells to use in the battery, putting 2 on the shelf as spares for the future?

 

[Q-Dog]

I would probably capacity test them all and use the 8 best. Short of that, I would measure their current state of charge and use the 8 that read highest. Then, as you use the battery take note of any cells that perform significantly different and replace them with the spares.

 

[carbon60]

I would probably capacity test them all and use the 8 best. Short of that, I would measure their current state of charge and use the 8 that read highest. Then, as you use the battery take note of any cells that perform significantly different and replace them with the spares.

Basically, you are suggesting to sort them by their current voltage and take the top 8?

 

[Q-Dog]

Basically, you are suggesting to sort them by their current voltage and take the top 8?

Yes, unless you can do a proper capacity test of each cell.

 

[MattiFin]

Capacity is not that important as even b-grade cells often come with reasonably close capacity. in many cases self-discharge rate would be lot more important parameter to match. Unfortunately it is not trivial to measure.
If you are not in hurry do a top-balancing for the cells and let them sit for a month. Measure cell voltages and drop out the two that are most faraway from group average.