Running a T-30/40 charger requires a 9500 RUNNING watt generator.. make sure that is running watt.
That gives you wiggle room for other power consumption (pump, fan, etc)
so 2 T-30/40 chargers will need 19kva
This charger should more than handle your application.
https://www.electricgeneratorsdirect.com/Westinghouse-WGEN20000-Portable-Generator/p117180.html