Spray the inside of a slow cooker with cooking spray.
In a small bowl, stir to combine salt, pepper, and chili powder. Rub the mixture on both sides of ribs.
Place ribs and chipotle chiles in slow cooker and pour Dr Pepper over ribs.
Cover and cook on low heat setting for 7 to 8 hours, or until ribs are tender. Remove ribs and discard liquid.
Brush barbecue sauce over ribs. To broil, set ribs on a baking sheet lined with aluminum foil and broil for 4 to 5 minutes per side, or until charred. To grill, place ribs on a grill over medium heat and grill for 4 to 5 minutes per side.
Let cool slightly before serving.