[Richard]

Doug gave good counsel. Two more things, unplug and do not run the gennie. Why? If the coach is powered the inverter charger is trying to charge the batteries. Disconnecting or arcing them could fry the charger. Second, connect ALL positive terminals first. Why? If you touch the wrench from a pos term to metal it will not arc until the neg terms are connected. If you touch a wrench from a neg term once it is connected you are already grounded.

Make sure your inverter is set for the battery type you are installing. Read the manual and set it up.