Place the roasted chicken carcass in the body of a large electric slow cooker. Add the apple cider vinegar, onion, carrots, celery, bay leaves, peppercorns, and salt. Pour water over the top to cover the chicken.
Cover with the lid and cook on low for 24 hours, or until the bones of the chicken crumble when pressed between your fingers. When it’s done cooking, ladle the broth through a cheesecloth or fine mesh strainer to remove the solids. Let cool slightly, then store in lidded mason jars in the fridge for up to 3 days. Enjoy as a warming beverage in the morning instead of coffee, or as an afternoon pick me up.