How do you calculate ABV when adding another batch of yeast starter in secondary fermentation?

[BonJoey]

Sorry if this was covered elsewhere. Just want to make sure I know how to calculate appropriately for my target ABV. Here are my stats:

OG: 1.045
Target FG: 1.005 (~5.25% ABV)
SG after primary fermentation: 1.014
SG after adding yeast starter: 1.019
FG to achieve 5.25% ABV: ?

Right now, my SG is sitting at 1.017. Not sure exactly how to calculate ABV at tis point. Do I just add the ABV from the pre- & post-primary and the pre- & post-secondary? Thanks.

 

[Sandy Feet]

What yeast are you using that will ferment down to 1.005?
Take the SG with a hydrometer as you are transferring into the fermenter post boil. I usually do mine about 1/2 way.
The difference between SG and FG (FG is taken after fermentation with a hydrometer) will determine alcohol. You use a calculator. There is one on this site.
You may also want to invest a few dollars buying the John Palmer book. It is a very good starting point for brewing.

 

[BonJoey]

What yeast are you using that will ferment down to 1.005?
Take the SG with a hydrometer as you are transferring into the fermenter post boil. I usually do mine about 1/2 way.
The difference between SG and FG (FG is taken after fermentation with a hydrometer) will determine alcohol. You use a calculator. There is one on this site.
You may also want to invest a few dollars buying the John Palmer book. It is a very good starting point for brewing.

Sorry if I wasn't clear in my original post. I'm good with calculating ABV. My primary fermentation stalled, so I added a yeast starter for secondary fermentation. I want to make sure I'm calculating right for my final ABV after my secondary fermentation is done or I achieve my goal ABV.

 

[dmtaylor]

https://www.thehomebrewforum.co.uk/...yeast-starter-to-a-stuck-fermentation.101447/

 

[Minbari]

ABV is a function of OG and FG. doesnt really matter how it got there

 

[TetersMillBrewing]

Sorry if I wasn't clear in my original post. I'm good with calculating ABV. My primary fermentation stalled, so I added a yeast starter for secondary fermentation. I want to make sure I'm calculating right for my final ABV after my secondary fermentation is done or I achieve my goal ABV.

Adding fresh yeast to your secondary should not effect your overall ABV because you have not changed the sugars available for the yeast to consume. Yeast attenuation and alcohol tolerance of the new yeast may play a small role on your final gravity, but it shouldn't make any significant difference. Now, if you happen to add something like glucoamylase amylase enzyme, which helps break down the complex sugars, you would get a higher ABV and would finish out somewhere around 0.998 as the final gravity (Not a good plan, makes your beer VERY dry)

 

[Ozarks Mountain Brewery]

https://www.homebrewtalk.com/threads/calculating-abv.701301/
https://www.brewersfriend.com/2011/06/16/alcohol-by-volume-calculator-updated/

 

[BonJoey]

https://www.thehomebrewforum.co.uk/...yeast-starter-to-a-stuck-fermentation.101447/

 

[dmtaylor]

FYI -- the resolution to this one that we reached on the other thread linked above is that the Tilt was not reading accurately. My guess is there was yeast or hop schmutz stuck to the Tilt. The other two readings are consistent at approximately 1.011 plus or minus a point. Didn't achieve his FG goal of 1.005 (impossible with Kolsch yeast and recipe), but DID achieve his ABV goal of ~5.0%.

 

[Zefram]

FYI -- the resolution to this one that we reached on the other thread linked above is that the Tilt was not reading accurately. My guess is there was yeast or hop schmutz stuck to the Tilt. The other two readings are consistent at approximately 1.011 plus or minus a point. Didn't achieve his FG goal of 1.005 (impossible with Kolsch yeast and recipe), but DID achieve his ABV goal of ~5.0%.

Band name: Hop Schmutz