Grandma Gwen's Beans

4 medium-size yellow onions, sliced
1/2 cup light brown sugar, firmly packed
1/2 cup apple cider vinegar
1 teaspoon salt
1 teaspoon dry mustard
1/2 teaspoon garlic powder
2 cans butter beans, drained and rinsed
1 can lima beans, drained and rinsed
1 can kidney beans, drained and rinsed
1 28 oz. can baked beans

Preheat oven to 350°.
Cook bacon, in batches, in a large skillet over medium-high heat 8 to 10 minutes or until crisp.
Remove bacon, and drain on paper towels, reserving desired amount of drippings in skillet.
Crumble bacon.
Sauté onions in hot drippings over medium heat 8 to 10 minutes or until onions are tender.
Add brown sugar and next 4 ingredients.
Cover and cook 20 minutes.
Combine butter beans, next 3 ingredients, bacon, and onion mixture in a 13- x 9-inch baking dish.
Bake at 350° for 1 hour.