Hi,
With different cell ratings you have to expect a different time for charging, which changes the 20, 40, 60, etc., points.
For example, with a cell rated at 2 ampere hours that's 120 ampere minutes, so 24 ampere minutes means 20 percent charged. But for a cell rated at 1 ampere hour that's only 60 ampere minutes so 12 ampere minutes means 20 percent charged.
With different cell ratings you have to expect a different time for charging, which changes the 20, 40, 60, etc., points.
For example, with a cell rated at 2 ampere hours that's 120 ampere minutes, so 24 ampere minutes means 20 percent charged. But for a cell rated at 1 ampere hour that's only 60 ampere minutes so 12 ampere minutes means 20 percent charged.