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Old 12-14-2011, 11:49 AM   #1
sivdrinks
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Default Calculating ABV with added booze?

Not sure how to do it. Added 8oz of 80 proof Jim Beam Black to the secondary of an 8.4ABV Imperial Stout, 5 gallons. Any ideas?


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Old 12-14-2011, 12:52 PM   #2
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A quick search turned up this formula:

(Beer Volume(oz) * Beer ABV %) + (Liquor Volume(oz) * Liquor ABV %) / (Beer Volume + Liquor Volume)

If I'm doing this right in your case it would be

(640 * .084) + (8 * .40) / (640 + 8) = 0.0879.. so about 8.8%

Hope that helps. Now this may be a stupid question, but what would be wrong with taking another gravity reading after adding it and simply recalculating the ABV? I figure that would work unless the extra alcohol somehow messes with the reading.



Reason: math error!
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Old 12-14-2011, 05:38 PM   #3
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Ya lost me on the math there. The beer is already bottled, took over three months to carb! Guess I should have taken another reading before bottling.
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Old 12-14-2011, 06:09 PM   #4
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Sounds about right. He just calculated the percentage for the whole batch. Each bottle will be about 8.8%.
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Old 12-14-2011, 06:18 PM   #5
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K, did it. Came up with 10.17. Thanks!
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Old 12-14-2011, 06:19 PM   #6
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Quote:
Originally Posted by theveganbrewer
Sounds about right. He just calculated the percentage for the whole batch. Each bottle will be about 8.8%.
Now I'm lost again.
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Old 12-14-2011, 06:23 PM   #7
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(640 * .084) + (8 * .40) / (640 + 8) = 0.0879.. so about 8.8%

That was for your specifications. The only reason is I'm doing the same recipe right now and I've come to 8.8 as well. How did you get 10.17?
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Old 12-14-2011, 06:28 PM   #8
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My bad, disleksic. You're right, thanks again!
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Old 12-14-2011, 06:35 PM   #9
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Very timely thread for me. Thanks, folks.
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Old 12-14-2011, 06:55 PM   #10
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Quote:
Originally Posted by bomberman View Post
Now this may be a stupid question, but what would be wrong with taking another gravity reading after adding it and simply recalculating the ABV? I figure that would work unless the extra alcohol somehow messes with the reading.
That gravity reading wouldn't do you any good because you're comparing it to the OG reading which was before the additional alcohol was added.


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