I never use carts, I always dry smoke. So with that in mind I will generally use three drips. With the 510 however, it doesnt matter how many drops you are putting in the 510 as long as you have the manual battery because the manual batteries are completely sealed. So if you have a manual battery on your 510 put 30 drops, who cares, it's not going to hurt anything, it will just get all over you hands.