Brown the ground beef in a skillet over medium heat; drain excess fat.
Chop the onions and bell peppers into small pieces.
In the slow cooker, combine the browned beef, chopped vegetables, and garlic.
Add canned tomatoes, beans, chili powder, cumin, and salt.
Stir everything together to ensure even mixing.
Cover the slow cooker with the lid securely.
Set to low heat for 6-8 hours or high heat for 3-4 hours.
Stir occasionally if possible to blend flavors.
Before serving, taste and adjust seasoning as needed.