DrkAngel wrote:WinForce 3s 5700mAh (20C) discharge test
2 cells of poor "comparative IR" dropped out early.
Oddly ... voltage recovered and equalized properly after discharge removed.
This seems to indicate that the "poor" cell can output the same mAh, at tested discharge rate, as the better cells ...
but that the mAh are only available at a lower voltage ... summing up to lesser wattage - actual capacity, from the cell! ... ?
Whether happenstance or some design function???
With some recently tested packs ...
Monitored cell level discharges seem to confirm a comparative IR as a reasonable (Yardstick method) indicator of actual capacity.
While voltage sag lets 1 cell hit LVC earlier, actual static voltage might still be equal with the better cells in series.
This seems to indicate that poor IR cell still outputs a similar percentage of its capacity as the good IR cells.
Severe voltage sag lets the poor cell output the same amps as the good cells.
Poor cell average discharge 3.40V x 5Ah = 17.0wh
Good cell average discharge 3.90V x 5Ah = 19.5wh
Poor cell at ~85% capacity of good cell diminishes pack performance severely!
Other tested packs quickly showed some poor IR cells as of obvious lower capacity!
"Showed" by rapid discharge voltage loss matched by static voltage loss.
IR is a definite factor in battery capacity among same manufacture cells!
Poor IR can either indicate poor capacity (cell discharges at lower voltage) or bad capacity (cell empties early)
Cells of poor comparative IR (within same brand-model cell) should be eliminated from any build!