I think a few things come into play here like chemistry of the cells.

From personal experience i have laptop pulls that where 2.5v and the input between 2.5-3v is only a few milliamps they cells jump up voltage really quick fairly low capacity cells. I have some Sony VTC5 that got over discharged to 2v and the same story not any really noticeable capacity below 3v if i remember correct under 100 milliamps.

You could always setup a test rig with a resistor in line and drain the cells to 2.5v and charge them using a charger that has a MAH reader.