Multiple Stages and ABV

[fendermallot]

I want to make sure I get this right.

if my OG is 1.054 and I want to add some juice to the brew after it's been fermenting but want to try and keep track of the ABV should it go something like this:

OG - Gravity reading before new fermentables introduced = XXX% ABV

Add fermentables

Grav Reading after adding extra fermentables added - FG = XXX% ABV

then add the two ABV's to get final ABV?

Did that make sense?

I just used the wife's steam juicer to juice 3#'s of pie cherries!

 

[Daze]

not quite. If you add the ABVs you will get a reading much higher than it really is. you need to do an average. lets say you have 15 cups of 5% ABV and then you add 1 cup of 10% ABV for a full gallon the final result will be 5.31%

(15c*5%) + (1c * 10% ) = 85

85/16= 5.31%