Bigbird65 wrote:
I would recommend that you buy a good inverter to take care of your 12v systems and charge your battery. If interested I can recommend a good one. If you haven't changed out your incandescent bulbs to LED, you should do that to save power.
Unless the OP is boondocking (which it doesn't sound like from his post), this would be a waste of money and effort. Even a small converter/charger will easily keep up with 12V loads if plugged in.
To the OP, check the cables coming off the battery. You should be able to follow them back to the converter. Even if the previous owner did a lot of customization, it would be very odd to totally eliminate charging capability but retain the 12v devices.