Put all the ingredients into a slow cooker. Add enough water to cover the ingredients plus at least two inches.
Turn on the slow cooker to low and let cook for 5-6 hours. You’ll know they are done when the beans begin to open up.
Turn off the slow cooker. If you would like to puree the beans to make refried beans, scoop out all the beans and place them in a separate bowl. Add about 1/2 cup of the water from the crockpot to the beans. Use an immersion blender to puree them, or puree in batches in your blender or food processor. Add more water as needed.