I put the following ingredients (which are always in my pantry) into the 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 *see note below
(1) 8 ounce can tomato sauce
6 slices crisp cooked 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 do NOT pre-soak the beans for this recipe.
Saute onions and fry bacon until almost crisp then drain well. 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 with a spoon, to thicken the juices.
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.