View Full Version : Calculating ABV, With mulitple additions

11-10-2010, 10:29 PM
Ok, So here's my delima: I want to be able to calculate ABV% with the way I do my meads. The mead calculator either can't handle it or doesn't make sense to me.

Here is my method. I wonder if I am doing this wrong.

Primary: This is my general show batch.

18 pounds of honey
2 gallons of water+ 2 gallons added to cool down (chilled)
2 packets of Lavin D-47 yeast
1 tablespoon of yeast energizer
1 Tablespoon of Yeast Nutrient

General batch. How I start it off. I heat it until the honey is nice and integrated with the water, then toss the nutrient and energizer and wake up the yeast in a plastic cup with just a little must from discribed above.

The yeast gets all bubbly and foamy by the time the must has reached 90-98 degrees. Then I aeriate by stiring viggerously. (ok, spelling sucks) Then after nice and stirred I toss in the yeast and stir again and then poor into carboy. This is sealed up with an airlock. I take a gravity reading before I airlock it. I usually end up with around 1.12. A bit of a heavy gravity.

I then wait til we are at about 1 bubble every 45 seconds to a minute to rack. When I rack I rack onto fruit juice and possible fruit pureed that wont juice properly. I take a gravity reading before and after. Sometimes the diffrence isn't much to speak of or my Hydrometer can't tell the diffence.

Then Rack in about a month or two. I usually see little activity here. Toping up with water when racked. Sometimes on subsquent rackings I add spices, nuts, or oak it with oak chips. That is usually the 2nd or 3rd racking. I try to make only one addition each time. I loose a little by racking it about once every 2 months but it ends up clearing beautifully each time. I never had a stuck fermentation this way and the way I am guessing it produces a mead that is ususally 15-17% ABV.

How can I be sure?

I get that I can be sure from the primary to the first racking onto the fruit juice as I do check the readings but things get muddled when I add the fruit juice or top up with either fruit juice or water and even more so when it is nuts like sliced almonds. I am not sure that the spices affect it that much and although oaking does a lot to flavor and smoothness I don't think that it effects the ABV%.

My recient batch is a Raspberry. I did the show mead then Pureed and de-seeded the raspberry and hit up the pulp with pectic enzyme. I used 11.5 pounds of raspberries, which ended up being about 1 1/4 gallons of prime red pulp, no seeds, of raspberries, red.

I am about to rack off of the raspberries after about 1 1/2 months. I plan on taking a grav reading then.

The Mead calculator assumes that everything is in the primary and to be honest, I have trouble making sense if it. I am decent with math so if someone were to give me a formula I could follow it. I have been told that for normal mead the formula is (OG-FG)X 1.31 for the ABV%. This means for every 2 points I get about 2.6% of ABV%. SO if a mead goes from 1.12 to 1.08 then the diffrence is .04. .04X1.31 is .0524 or 5.24 ABV%. Am I correct? How does this change with the additions I make as I am adding sugar with the fruit?

Please help, Matrix

11-11-2010, 12:57 AM
For additions you can use the mixing formula: P1*V1 + P2*V2 = Pt*Vt where V is volume, P is some property you care about (sugar content, abv, etc), and 1, 2, and t are the two things you mix and the total.

Example: You have 5 gallons of mead with 12% abv. You add 1 gallon of water (0% abv). The total is then given by 5*12 + 1*0 = x*6, x = 10% abv.

For fruit, the mead calculator has some built-in estimates of sugar content for different fruits. If you have a better measurement, use it; if not, the ones in the calculator should be close. Using Brix instead of SG is easier when doing blending calculations.