I put the following ingredients (which are always in my pantry) into a large crockpot before I go to bed and let them cook on LOW all night.
2 cups DRY navy beans (do not soak)
6 cups water
1/2 cup dark brown sugar (light brown sugar works well too)
3 teaspoons salt
1/2 teaspoon pepper
1 teaspoon dry mustard powder
3/4 cup sweet onion chopped small and sautéed
(1) 8 ounce can tomato sauce
small pinch of cayenne pepper
6 slices crisp cooked and drained bacon
Now, a word about the beans: Over the years, I've tried every kind of DRY bean there is and they ALL work, however, the tiny little "navy beans" work the best and tolerate re-heating without going mushy. I highly recommend that you use navy beans. Make sure you rinse and sort the dry beans, but do NOT pre-soak them.
Put everything into a large crockpot and cover with 6 cups of water. Stir well and set on low for 12 hours. The last 3-4 hours, prop the lid of the slow cooker open (just a little) with a spoon, to thicken the sauce.
Note about onions: When I decide to make these beans (and I'm out of fresh onions), I use a scant tablespoon of dehydrated onion flakes, they work well.