Season the chuck with 1 1/2 teaspoons of the salt, heat the oil in a skillet over medium-high heat, and brown the roast for 3 minutes per side.
Place the roast in a 6-quart crockpot and add the onion, chili powder, tomatoes, all 3 beans, broth and remaining salt.
Cover and cook on low for 7 to 8 hours until the beef is fork-tender and reaches at least 145°F.
Transfer the beef to a board, shred it into bite-size pieces, and discard any large pockets of fat.
Return the beef to the crockpot, stir, and cook uncovered on high for 15 minutes until the chili thickens.