A 2003 model Sunline, What power converter do you have?
If it is an American Enterprizes and looks like this, pull out the qty 2, 30 amp green fuses in the top slots. Those 2 fuses feed the DC bus bar in the converter panel to the battery. See this pic.
If you re really into this, you can see the Red battery hot lead, then it splits to 2, 30 amp fuses to feed the rest of the circuits.
Switching off the 120 breakers will not do anything for draining the battery. It is on the AC side of the fence.
I do not know your exact model or the fuse under the bed. But my 2004, T310SR, made in Oct 2003, had the disconnect switch on the frame. I had heard that the 2004 year model was when the rotary disconnect came about. If that fuse under the bed, is the 30 amp to the battery, then yes it too will detach the battery. The converter box maybe be handier then under the bed pending your layout and converter. Yes unhooking the battery will for sure do it. But dealing with that Attwood battery case strap if one real pain in the foot after each camping trip. That is if yours has that same strap. Every time I take mine off, I have to refigure out how it goes back on.
Good luck and hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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