I have a XPS dual bank 10/10 charger, vsr, battery switch, and two Optima Blue batteries. The charger's normally plugged in and the switch set to off so the banks can charge independently while garaged. I like to flip the switch and run the stereo while working on the boat. It's just over 1000 watts total & never crank it too loud in the garage - maybe 1/4, so ~20 amps @ 14V. The charger has "Tranfer On-Demand" so that supposedly all 20 amps are available to the stereo battery if the house battery is charged.

Will I damage the charger if I keep it plugged in while playing the stereo? Will a plugged-in charger act as a transformer & keep from draining the battery while the stereo's playing?