When on inverter am I using the batteries?

dougrainer wrote:
Msturtz. You have "experience"? I have 38 years as an RV technician and still working. I guess I have experience also:B From just one of the various RV Transfer switch makers instructions. Doug

BEFORE TESTING:
Ensure air conditioning units and other high current users are switched off. It is
harmful for the transfer switch to switch over power sources while under load.
Shut down all power sources to the RV
Label power sources clearly that testing is in progress.
If accessible, remove the lid of the ATS to visually check function

Are you saying that you have documentation from the ATS manufacturer(s) that state that all power must be removed when switching power sources? If so, I would absolutely love to see it. I have seen some crazy things in the RV world that would arguably not comply with NEC or any other rational code. That said I work for a heavy truck manufacturer in the Research department. I have specified, removed, & installed large UPS systems as well as I have installed standby generator system with 100 AMP split phase computer controlled transfer switch. I have also installed split phase 240 VAC EVSE equipment that similar to ATS equipment the transfer is ALWAYS done "under load". Your point about arcing across the contacts is possible especially with very old and slow switch gear but with modern switch gear the components should last the life of the coach. Having said all this it is usually a good idea to turn off large loads when switching especially when switching from shore to generator. The reason is many generators are under powered and will sag voltage and spike current when a sudden load is transferred over. It is better for the generator to have a smaller load transferred. In my coach the generator is biased by the switch gear so if the generator is on it is powering the coach. I also have an EMS system with a 2 minute delay timer. The net effect of this is the incoming power is delayed by two minutes before cutover. Also my coach as an AGS (Automatic Generator Start) system. By definition, I would not be able to run around switching off power before the system starts the generator. It happens automatically without any intervention from me. If it was damaging or unsafe to "hot switch" between inverter and generator power I'm quite sure that the coach manufacturer would not have installed such a system.