You may want to double-check those voltages before you order a charger and configure your BMS.
Those Gen 1 Leaf modules have 4 x 30AH cell pouches connected as 2 series of 2 parallel cells.
The nominal useable cell range is 3.65v to 4.2v, but is recommended to stay below 4.1v/cell.
That gives you a usable voltage range of 51.1v to 57.4v.
You can go lower than 3.65v, but You may want to look at the discharge graph for those cells, the "knee" on the curve becomes really steep below 3.65v and the voltage comes down pretty fast.
