Reading the charger speck, max charge on a LiPo battery is 1C.  So assuming a 4 cell 3000 mah battery it would take a 44W input to charge at 3 amps.  Doing 4 at a time would be 177 W.  5 Cells takes 222W.  6 Cells takes 266W (assuming 3.7V per cell: 3.7V x 3 amps x 6 cells x 4 batteries = 266W).  So even allowing for losses, charging voltages and etc. a 400 W power supply should do.  However the charger speck calls for 30A minimum power supply indicating a 450 W supply is needed.  So I recommend you look at what batteries you plan to charge and if it is less than 300 W you should be safe.
I am sure others may have experience on this matter and will comment.