Please explain change in ABV

[suzanneb]

i made a 5 gallon batch of honey porter.
after 2 weeks in primary abv was 1.020 i bottled 4 gallons and put one gallon in secondary with more honey. i added the honey to give it more of a honey flavor as well as raise the abv a bit maybe. it bubbled and bubbled and 2 weeks later the abv is now 1.017.
so how come it went down. shouldn't with the extra sugar it go up????
please explain.
j

 

[kh54s10]

That is SG (specific gravity) or FG (final gravity) if it originally stopped at 1.020 that would have been because the yeast converted all the sugar available. You added more sugar that was easily fermentable so the yeast went back to work.

I guess the added sugars made the yeast take the gravity even lower than the first part of the fermentation.

 

[wailingguitar]

What you are reading isn't ABV, it's Specific Gravity... Specific Gravity, essentially, is a measurement of density relative to water. It is supposed to go down as the beer ferments... the yeast is breaking down sugar, part is released as CO2, part is turned into alcohol (which is less dense than water)

Your hydrometer may have a "potential alcohol scale" on it. The idea is that you take a reading before fermentation begins, and another when it ends. Subtract the final reading from the first to get an approximation of ABV. Example; your hydrometer shows a 'Potential Alcohol' of 6.5% before you pitch your yeast... when it is finished it shows a reading of 2%... 6.5-2= 4.5% ABV

 

[nascarazy]

Your abv would be your original gravity (OG) minus your final gravity (FG), then multiply the difference by 131. Your numbers are your FG.

 

[suzanneb]

ok.
orignal was 1.080
final as of right now is 1.017

so 1.080-1.017= .063

.063 x 131 =8.25%
does that make sense

whereas the one i bottle at 1.020

1.080-1.02=.060
.60x131= 7.86%

wow that sounds really high.
the o.g. was supposed to be 1.056 and i got 1.080 does that mean the honey i used was extra potent or that i got really good efficiency. keep in mind this was a extract and partial grain recipe.

 

[Wig]

you were shooting for 56 and got 80? That is way more than improving your efficiency.
Did you have honey in the main part of the recipe? Did you account for it as a fermentable? Please post your recipe.

 

[iambeer]

My opinion as a newcomer to brewing is ... you are definitely gonna get drunk drinking this stuff.

 

[ajf]

ok.
orignal was 1.080
final as of right now is 1.017

so 1.080-1.017= .063

.063 x 131 =8.25%
does that make sense

whereas the one i bottle at 1.020

1.080-1.02=.060
.60x131= 7.86%

wow that sounds really high.
the o.g. was supposed to be 1.056 and i got 1.080 does that mean the honey i used was extra potent or that i got really good efficiency. keep in mind this was a extract and partial grain recipe.

Was this an extract batch? [EDIT] Sorry, you said it was an extract batch. [/EDIT] If so, and you ended up with the required volume, your O.G. would probably be very close to 1.056. So why did you measure 1.080?
My guess is that you added top-off water, and you didn't mix it thoroughly before taking the O.G. sample which you took from the bottom of the fermenter (or you took the sample before adding the top-off water).

As for the 1gal that you added the extra honey to, how much honey did you add? Assuming that the O.G. was really 1.056. You would have to increase that by 0.042 for each # honey you added, so if you added 1/2 # honey, you would increase the O.G. (for the purpose of ABV calculation) by 0.021.
i.e. 1.056 + 0.021 = 1.077
1.077 - 1.017 = 0.060
0.060 * 131 = 7.86% ABV

-a.

 

[suzanneb]

here is the recipe i used
http://hopville.com/recipe/1342086/robust-porter-recipes/panama-honey-porter

i can cut and paste if you want.

i added 16 oz of honey and boiled for 60 min.

not sure about the 1.080 i did add a 1/4 -1/2 gallon of water to make it up to 5 gallon batch. so it is possible about the added water and taking a reading but i am pretty sure i shook it up first.

then i lost about that much in intitial fermentation out the blowoff tube.


as far as the 1 gal batch i only added honey after 2 weeks of fermentation can't remember how much but maybe 4-8 oz or so. not alot.

i am guessing this beer is not 7 or 8 percent but more like 5 or 6. it just doesnt taste that strong. is there a way to know exactly what the alcohol content is?

 

[suzanneb]

one other thing i didn't weigh my honey i used 16 fl oz. not sure if that means i used too much or not enough. i know a pint of water weighs a pound but a pint of honey who knows?

 

[Wig]

ok I think we are closer to an answer. The pound of honey was not accounted for in the fermentables

I plugged the recipe into beersmith and got 1.056 WITHOUT the honey. With a pound of honey i got 1.063. With a half gallon boil off, I got to 1.073. If you measured your gravity hot, at around 105, that would give you a corrected gravity of 1.080.

So, when you took your measurement, was the wort hot? and was it before you topped off with water?

The only way to know the alcohol content is to know the original gravity. The mini batch with additional honey won't be much more. The yeast might not do much with it if they are tired or beyond their alcohol limits. Even if all the extra honey fermented, 8 ounces would only add around .004 gravity points.

 

[suzanneb]

it wasn't hot when i measured. and there wasn't boil off i just didn't sparge with enough water i guess. i wasn't keeping track very well and came up short.
but it is much closer.

that stinks there is no other way to find out other than o.g. i just made another batch of something and forgot to measure it before i added yeast. i guess i wil have to guess based on the recipe.