What causes FG to finish high?

[alexipas]

I made 6 beers last month. I just bottled the last one today. The first two finished roughly 1.011-1.014.
the next 3 finished 1.019.
My assumption? Yeast was spent right? Except.... I the batch I bottled tonight finished at 1.011.

All batches were brewed with my Brewzilla with a grain bill of roughly 13 pounds. Am i not extracting all the sugars? Wouldnt that be reflected in my OG?

I will admit im lazy but im consistent. I have a mother yeast starter. After every brew day I steal 1 liter of wort and build my starter back up on a stir plate then fridge it. On brew day I pour half my starter into the wort then top the starter back up with 1 liter of cool wort and repeat etc

How can my yeast slowly get worse and then perk up? I realize that I dont measure how much yeast im adding so that doesnt help either. am i adding 100million or 500million each time? No idea.

Only differences between the first 5 batches and this one today were as follows.
All batches were these malts 5%cara crystal, 15%Munich and 80% 2Row

first 5 beers were 1.060 OG, IPA's, 5 oz of dry hops in each batch. Cold crashed FG= 1.019
last batch blonde ale with the same malts 1.044 OG, no dry hops, no cold crash FG= 1.011

I mentioned the cold crash because its the only other difference between batches( yes i did use the gravity temperature calulator)

My thoughts? Maybe I didnt add enough yeast to my higher grav beers???
This sucks because with high FG my beers are not dry/crisp and lack body.

I would just buy new yeast and start again except COVID19 has made that difficult and because my yeast clearly works haha.

Any pros have some thoughts or anything I can try for my next batch?

 

[RePete]

What is your fermentation temperature? I see you are in Ontario. I have been the same situation...brewing a lot more since the shutdown. I have a Robobrew v3, and have been brewing similar beers. My beers generally start fermentation well enough, but have just been very slow to finish. I did a Zombie Dust clone last month that took 4 weeks. It finished at 1.010. It went to the keg, tastes great, but I was nervous about it for a while. I thought maybe the dry hopping extended fermentation time. Mostly though, my beers are sitting on the floor in the basement, and it’s probably too cool. That’s what I am blaming.

I had a batch that seemed to finish after a week. It had stopped bubbling. I don’t have a good way to draw a sample from the carboy, so I went ahead and kegged it. When tested, FG turned out to be 1.020, when OG was 1.060. Since it was high I didn’t cold crash it, and am letting it finish in the keg. It is obviously still fermenting. I purge CO2 from the gas port every little bit. It is all foam from the tap.

 

[Jag75]

Are your OG readings hitting their predicted mark? 13 # of grain with a total abv of 5.38 seems a tad low to me. Could be your yeast , maybe it's not viable enough. Could be your mash temp . Maybe it's your hydrometer . Have you checked to make sure its reading correctly?

 

[OnePlate]

Are you using any yeast nutrients? Which yeast strain are you using?