Our new BT Crusier will not start after sitting a couple days. Installed a new battery and it still does it. We are not leaving anything turned on. Any idea what is causing this. Nothing in the coach runs off this battery, just the Ford.
Try disconnecting the positive battery cable and using an ammeter see how much current is being drawn with the ignition switch off. The radio memory and maybe some other small things draw current even with the switch off. If the draw is minimal (less than 1 amp) I say you got a bad "new Battery". It happens.
Be careful as most multi-meters are only rated for 2 amps or less in the current (amp) mode.
Also if you take it to an Autozone or NAPA store they will check it all out usually for free.
Do you have a battery switch on the dashboard that allows you to start your engine with the house batteries? It's the momentary contact switch with the battery symbol on it. Hold it down while you crank the engine.
Your chassis battery has various draws whether using it or not due to the electronics in the system. We had the same problem in our 2016 BT after about six months and found the battery itself was defective with two dead cells. After installation of the new battery, the problem disappeared