You need to first start with the battery bank. If you have a bad cell in the bank the charger will continue to try to get the voltage up to where it should be and thus boil the cells of batteries in the process. Once you have a good battery bank, then test and diagnose if need be, the inverter/charger. Most of the time it is just bad batteries. Also make certain the charger settings are for the type and size of battery bank you are using. Good luck and keep us posted.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7