Piggybacking cells to help weak cell groups


Photon Sorcerer
I have some of those large 24v batteries from Battery Hookup. The cells are welded in. It looks like 2P8S, about 100ah cells. I started to bottom balance one of them and cell group 7 voltage went down first, meaning its capacity is less. I can’t take more power from the battery without that one cell group going too low.

So I was thinking…I have some small LiFePo4 cells that I could piggyback in parallel with the cell group, raising the capacity of the cell group. That should allow more of a balanced discharge.

Note, it is not uncommon that people build batteries of out of a mixed capacity of 18650 cells, grouping a large number of cells in parallel to make one cell group and maybe a slightly different number of cells for the next cell group, just to keep each group with the approximate same capacity. So it would be reasonable that one could bolster a cell group with some add-on capacity.

Any thoughts?