Place the bones or chicken carcass in the pressure cooker.
Top with add ins, if you have chosen to use them. (Vegetable scraps and ends like onion, garlic, carrots, or even fresh or dried herbs; optional.)
Cover the bones with water. Use 16-24 cups (1-1 ½ gallons) depending on desired strength of bone broth. That's 16 cups (1 gallon) for stronger bone broth, or 24 cups (1 ½ gallons) for lighter bone broth.
Seal the electric pressure cooker as directed and set on manual setting to high pressure for 2-3 hours time. 2 hours for lighter broth, 3 hours for stronger. Don't go over 3 hours, as that can be too long.
Allow the pressure cooker to release steam naturally, carefully remove lid away from face and let cool.
Pour the cooled broth through a fine mesh screen to strain out pieces. (Use either one large pot to divide the bone broth up later, or pour directly into storage jars.)
Chill the strained stock in the fridge to allow fat to solidify and separate, then skim it off the top to remove from stock.
Store in plastic bags in the freezer, or in the fridge in air tight containers.