Pentalobe/pentaleg tops, could these be Shenzhen BAK made?
Henrik, I think the calculated internal resistance figure in your charts needs a fix. “Cold” or barely warm cell DC internal resistance can be inferred from the discharge curve graphs. An easy algorithm could be “at ⅛ capacity figure value x-axis position read V(IREF) and V(IMAX) voltage values, then work out Rcell = (V(IREF) − V(IMAX)) / (IMAX − IREF)), whereas IMAX is the maximum current at which the cell succesfully completed discharge without issues or overheating and IREF could be the closest amperage value for which a measured discharge curve exists at ≈¼ of IMAX. In this particular case (values taken at 250mAh point):
Rcell = (3.83V − 3.4V) / (20A − 5A) = 430mV / 15A = ≈28.67mΩ.
