If using uncooked bratwurst, prick casing and steam for 10 minutes to release excess fat. This step may be eliminated if using fully-cooked smoked sausage or kielbasa.
When the sausage is cool enough to handle, cut into 1-inch pieces (do the same if using kielbasa)
Brown sausage (or kielbasa) in a large skillet over medium-high heat.
Add browned sausage to slow cooker.
Add the sauerkraut, juice, sugar caraway seeds and potatoes. Stir to combine.
Cover and cook on high for about 3 hours, low about 5 hours (times are approximate)
Notes
You can use more caraway seed if you really like them.