Place the turkey carcass in a very large pot. Add the onion, celery, carrot, bay leaves, rosemary, thyme, peppercorns, and apple cider vinegar.
Fill the pot with water. This will likely be close to 16 to 18 cups of water, but this depends on the size of your pot. Some of the water will evaporate during the cooking process.
Bring the water to a boil. Once boiling, reduce heat to low, cover, and cook for 12 to 24 hours.
When the cook time is complete, pour the broth through a large fine mesh strainer set over a separate large pot. Discard the carcass/scraps from the cooking process.
Allow the broth to cool completely before pouring into wide mouth mason jars. Fill the mason jars about 3/4 of the way to allow for the broth to expand once frozen. Store in the fridge for 7 to 10 days or freeze for about 3 months.