Brown the ground beef in a skillet until it is fully cooked and has developed deep brown spots, then drain away the fat and transfer the beef to a 6 quart or larger slow cooker. The browned beef should smell savory and look crumbly rather than gray or wet.

Add the tomato sauce, drained kidney beans, drained pinto beans, undrained diced tomatoes, onion, celery, green bell pepper, cumin, chili powder, black pepper, salt, sugar, and beef broth, then stir until evenly combined. The mixture will look loose at first, with vegetables and beans suspended in a bright tomato broth.

Cover and cook on Low for 8-10 hours or on High for 4-6 hours. The chili is ready when the broth is thick and brick-red, and the celery and bell pepper are tender with a slight bite remaining.