I have a 1999 dutchman lite I just purchased. It has a three way fridge. As I camp mostly in campgrounds without power and I leave it at the lake when I am not working the battery keeps running down every couple of days due to the fridge needing power to run even though it's running on LP GAS. It never had an owners manual with it. Is this working right or am I not finding a switch to make it independent of 12 volt as the older three way fridges?