Xw6848 Pro Loud Noise & Vibration

I just finished installing 2 XW6848 Pro inverters. When I power them up on battery power everything is normal. I get a slight hi pitched noise that is not loud with no vibration on the case. When I switch on the breaker that supplies 240v to the AC1, it goes through AC qualify cycle. There is still no loud noises at this point. When it switches over to the charge cycle I hear a loud humming or buzzing noise, however you want to describe it. I also feel a vibration on the case of the left side inverter. These inverters are in a 5 foot wide by 3 foot deep room, with the doors closed standing outside I can still hear it. I have isolated each inverter and power each of them up individually as a split pase primary inverter. The right inverter makes no noise when it enters charging mode. The left one makes noise and vibrates. The batteries were basically fully charged when turning on this system, so the charging output was 1/2 amp. There are no major loads on the charging circuits at this moment. I have tested the voltage coming out of the AC1 breaker and it 240 across the legs, individual legs test 120 to neutral & ground. bulk/boost and absorption voltage settings are set at 50.4v as listed on the battery specs. This is set-up as 2-stage charging & lithium ion battery type. I have set charging output to 60 amps max on all charging modes. I am in need of some assistance in the next steps I should take.