Ongoing Brew Problems - 8th batch

[jimbrew_jr]

I just finished brewing my 8th batch and I continue to have issues with carbonation and alcohol content. I am a extract/Partial mash brewer. I brew 5-5.5 gallon batches.

My last two beers I added 150g dextrose prior to bottling. One beer ended up over carb'd champagne style bubbles. The other beer ended up flat as juice. I just dumped my 8th batch into the fermenter and I do not want to run into these same problems again. I can provide additional details on my procedure/recipe as needed.

Alcohol content Issues:
My last batch had
4lbs briess light LME
4 lbs Briess Wheat LME
6 oz brown sugar
3.6 lbs roasted pumpkin. In a 5.5 gallon batch i got an OG from 1.045 to a final OG at about 1.012 4.33%. I anticipated a higher abv%. Did i just not account for my fermentables correctly?

Lastly:
I tried to jump to partial mash this batch despite my previous issues.
Fermentables:
4lbs Rahr 2 row
4lbs Briess gold LME
12oz crystal 90
4oz carapils

I got an OG of 1.043. Much lower than I wanted on the 5 gal batch.
Questions about partial mash. I mashed at 150-165 for 50 minutes. I have an electric stove and struggle with maintaining a constant temp in the 144-154 range. I then briefly sparged by pouring water over the muslin bag of mashed grain and then steeping the grains with all of my wort at a higher temp about 170. Then I dumped the 4 lbs LME and cranked heat to get the wort to a boil.


I apologize in advance for my stream of conscious brew issues rant. I just want to be able to improve and correct any bad habits I have established. I appreciate any help anyone can provide.

 

[Euphist]

Depending on temperature and style, 150g per batch might be a bit much. As for the flat batch, I would try swirling the bottles to rouse the yeast and place them in a slightly warmer place for a couple more weeks.

As to your first batch, your OG is either a result of incorrect measurements of ingredients, of a faulty gravity reading. Odds are, it is the second. It is very common in extract brewing to get incorrect gravity measurments due to incomplete mixing.

As to the second batch, I plugged your recipe into BeerSmith and it gave me an OG of 1.046. I would say that the OG that you got is pretty respectable, especially for your first PM. Your procedure seems pretty sound. If your pot will fit in the oven, that will help you to maintain mash temperature.