Smoky Bean Casserole

2- 15 oz cans kidney beans
2- 15 oz cans butter beans
2- 15 oz cans pork and beans
1 onion
1 cup ketchup
1/4 cup brown sugar
1 T. liquid smoke
3 T. vinegar
1 tsp. salt
1 tsp. pepper

Cook in crock pot 6 hours or in oven at 350* for 1 hour.