Low Alcohol content

[njersey1211]

I am still a new brewer and I am still using kits that I get from the internet. So far I have liked the beer that I am brewing. My only issue so far has been lower then expected alcohol content. I brewed an IPA and was expecting a 7.2-7.5% ABV but I came up with a 5.6%. Not horrible but the last few batches of beer that I have tried have all be 20-30% low. I have tried different kits and different suppliers with no change. Is this normal to be off by 20-30%? Thanks

 

[AVLbrewing]

Assuming you are topping off (and not doing full boil extract brewing) the most likely culprit is you aren't getting an accurate sample of your wort. Here is a thread detailing what could be the possible culprit:

https://www.homebrewtalk.com/f39/at...inal-gravity-reading-wrong-dont-panic-289735/

Essentially it is difficult to get the boiled wort to completely mix with the top off water. When you then take a hydro reading it is off, which would result in an off ABV%.

The only other thing is if you are doing full boils, in which case you are starting with too much water when you boil, and thus diluting your beer.

 

[NivekD]

Nope, not normal at all...can you tell us more about the kits and how you brewed them? Extract kits should come very close the expected ABV as long as you're not adding too much water.

 

[amandabab]

20-30% error with an extract kit means something is very, very wrong.

Are you using the gravity #'s on the hydrometer or trying to use the potential alcohol content scale?

The potential alcohol content scale isn't that useful for beer.

 

[njersey1211]

I am doing a full boil and the last kit I made was the Zythos IPA from MoreBeer! I have been following the receipt pretty closely. I start off with 6.5 gallons. My stepping gains took 45 min to make it to 170 F. The rest of my boil went correctly and I fermented for a week before dry hopping for 13 days.

 

[AVLbrewing]

I am doing a full boil and the last kit I made was the Zythos IPA from MoreBeer! I have been following the receipt pretty closely. I start off with 6.5 gallons. My stepping gains took 45 min to make it to 170 F. The rest of my boil went correctly and I fermented for a week before dry hopping for 13 days.

What's your boil off rate and how much are you putting into you fermenters, and ultimately bottling bucket/bottles. You are probably over estimating your boil off rate, or over estimating you loss of water due to hops/trub.

 

[njersey1211]

I am normally putting more then 5 gallons into the carboys. I have another kit and I will try cutting my starting water and try it again. Thanks

 

[wormraper]

I am normally putting more then 5 gallons into the carboys. I have another kit and I will try cutting my starting water and try it again. Thanks

if you're putting more than 5 gallons in the fermentor that's your problem. those kits abv is measured with exactly 5 gallons of beer in the fermentor.

 

[AVLbrewing]

I am normally putting more then 5 gallons into the carboys. I have another kit and I will try cutting my starting water and try it again. Thanks

A pretty common boil off rate it seems is around 1 - 1.5gal per hour. I went with this my first full boil and ended up with a low OG (and closer to 6gal in primary). My boil off rate is closer to .5gal/hr. I think most extract recipes call for partial boils, and then topping off to make 5gal in the primary. Do you remember how much over 5gal you put in the primary? Was it just a hair over 5 or closer to 5.5gal or even 6gal? The best way to calculate boil off is to do a test boil. Fill your kettle with 6gal, boil it for an hour, the measure the amount left over.

 

[njersey1211]

AVLbrewing- sorry its taken me so long. I boiled 5 gallons last night and I am losing about 3/4 if a gallon over the hour. I think my plan for my next boil I am going to cut my starting water to 6.5 gallons and if I am under then just topping the wort off.

 

[njersey1211]

Correction 5.5 gallon start