Place a large skillet over medium-high heat and sauté beef until it releases fat (4-5 minutes), breaking it up with a spatula.
Add onion to the skillet and sauté until tender (4-5 minutes).
Add minced garlic and seasonings: cumin, chili powder, garlic powder, dried oregano, salt and pepper.
Cook another 30 seconds stirring constantly.
Transfer mixture to a 6 Qt slow cooker.
Add rinsed and drained beans, diced tomatoes with their juice, diced tomatoes and green chilis with juice, and tomato sauce into the slow cooker.
Stir to combine.
Cook on high for 3-4 hours or on low for 6-8 hours.
Season to taste if desired and serve warm.