Fast Ferment and high ABV

[Kevbud]

New All grain brewer here, with a Robobrew on my third brew. It was a blind pig recipie kit. I only put 5 gallons in the fermenter and the OG was 1.071 which is on the high end of the target. I mashed at 151. I calculated a brewhouse efficiency of only 62% I pitched at 65 a packet of gigayeast ale yeast and allowed the fermenter to rise to 68 naturally and kept it there consistently. I just checked my gravity and its at 1.010 4 days later which i assume is pretty much done with the primary. I calculate an ABV of 8% which the recipie targeted 6.5%. I have a few questions.

I know some of my high ABV was a high OG but What caused me to ferment to a lower final gravity than what was expected by the recipie thus resulting in a high ABV.

thanks

 

[Rob2010SS]

Your final gravity in a recipe is always going to be an estimation. Yeast are living organisms and will somewhat do what they want. A couple of thoughts...

You say you mashed at 151. Are you sure? Did your temperature drop lower shortly after you started? How accurate is the thermometer you used to check temp? Was 151 what the recipe told you to mash at?

In the recipe you had, what was the target OG and the target FG? Is a majority of the difference on one end or the other?

Essentially you ended up with more fermentable sugars than what the recipe planned on, which isn't necessarily bad. Is there more details about the recipe you can share? Is there a recipe sheet that came with the kit?

 

[Jag75]

What did you use to check your FG? If I were you I would do starters when using liquid yeast. Sounds like you got way better then 62 % efficiency. You say you put 5 gallons into the FV , was your amount of wort right?

 

[Tallgrass]

The more beer kit? Their estimated OG is 1.065-.069. They also estimate 6.5 ABV. Are they assuming the yeast is going to stop at 1.020? What was their recommended mash temp?

I brew a lot of more beer kits with minor changes and the numbers are usually right on with closer to 6 gallons into the fermenter. I just ordered and almost bought that kit. Curious how it turns out.

 

[kh54s10]

The difference would be the OG and the FG and volumes of the brew as compared to the predicted OG, FG and volumes of the recipe.

Changes in any one will change your ABV.

Changes would be caused by many different factors including Mash temperature, grain milling, volume of preboil, volume of post boil, Yeast attenuation, among others.

Without knowing what the kit's predicted OG and FG were, anything advised now is just speculation.