Lightly spray the crock of your slow cooker with nonstick cooking spray. Add the beans, chicken broth, onion, salt, pepper, and about 1/2 of the bacon. Cover and cook on high for 4 to 6 hours or low to 6 to 8 - or until the beans are tender to your liking. Stir the beans a couple times during cooking. Serve topped with the remaining bacon pieces.