What you are describing is how CC/CV charging works. The charge starts in CC (Constant Current) mode which is pretty much how we're used to seeing charging. At some certain point (90% capacity or so?) the charger switches over to a CV (Constant Voltage) charging mode where the battery is maintained at a pre-determined voltage and charging current gradually drops off.
ANY battery charged at constant 1C (LiPo or NiMH, etc) would take approximately 1 hour to charge from complete discharge. Having the algorithm change off so the last 10% or so of capacity is charged at an ever reducing rate makes 83 minutes total seem quite reasonable.
That said, right now my batteries are taking something less than 3000mah to recharge after a heat (13.5 SuperStock class) so the recharge at 4.9amps (1C) takes about 45-50 minutes.