Rinse beans; soak in water overnight. Drain and place in slow cooker (4.5- to 6- quart pot). Stir in brown sugar, ketchup and chipotle chili; set aside.
In skillet, cook pancetta, onion and garlic over medium heat for 8 to 10 minutes or until onions are soft and pancetta is lightly crisp. Scrape into slow cooker. Stir in 2½ cups boiling water. Cover and cook on HIGH until beans are tender, about 5 or 6 hours. Sprinkle with green onions before serving.
• Substitute diced bacon for pancetta if desired.
• Adjust the heat by adding more chipotle chilies to taste.