If you plan on being off grid and using a generator to charge, make sure you get a good battery monitor that tracks actual amps in/out of the battery. This way you will get a better idea on just how much you are using, your battery condition, and can even monitor the charge rate. I use the
Trimetric 2030, but there are other options too.
For true 50% discharge of a 100 A/hr battery, figuring 15 A/hr charge rate to 90% capacity would require 40 A/hr which is 2.67 run time. After about 90%, your charge rate will start to drop.