Cook ground beef in a skillet over medium high until meat is no longer pink. Drain off any fat.
Add the onion to the ground beef and cook for 5 minutes until the onion is soft and translucent.
Transfer the meat and onion from the skillet to the slow cooker. Add the ketchup, water, celery, lemon juice, vinegar, brown sugar, Worcestershire sauce, salt, and mustard. Stir well to combine.
Then add the beans, tomato sauce, and chili powder. Stir again and cook on low for 2-3 hours.
Serve warm with corn chips, saltine crackers, oyster crackers, cheese, sour cream, or over baked potatoes.
Notes
You can use ground beef, ground turkey, or a combination of both. My friend does a mix of half ground chuck and half ground turkey, I usually go with a lower fat ground beef because then I don't need to drain off as much rendered fat.For the beans, I generally do a mix of 3 beans, red kidney beans, cannellini beans, and pinto or black beans.