Oztops ABV

[BonezAU]

I'm currently doing my first brew with Oztops and juice from the supermarket.

I bought a hydrometer so that I could check out what sort of alcohol level I'm getting and have some questions.

The first brew I put on was Woolies brand Apple & Blackcurrant juice, in a 2L bottle. I poured 1 cup of juice, added 150g of white sugar and half a cap of the supplied No. 1 wine yeast.
The SG was 1.063 after adjusting it for temperature. I did check the SG before adding the sugar and it was around 1.041, from what I've read this is quite normal for off the shelf juice.

After 7 days of fermenting (at between 20-28C), I chilled it overnight in the fridge and then opened it to take another sample. It was 1.020 exactly, which to my calculations brings it to about 5.78% ABV, a little disappointing to be honest as I was hoping it would be closer up around the 8% mark, but hey - this is my first batch and it's all about trial and error, right?

The bottle still felt a little "puffed" but there wasn't very much activity going on and hadn't been much in the last few days either. I decided to take it out of the fridge and add another half cap of yeast to see if I could get it going again. It got a bit excited and I could hear air coming out of the Oztop for a while but it's now gone fairly quiet again - it's not in the fridge any longer.

Can anyone with more experience please tell me if:

a) adding more yeast was a bad idea
b ) with an SG of 1.063 and 7 days of fermenting, should I have expected the FG to be lower or is 1.020 about right?
c) did I add enough sugar to get an ABV around 8% or would I need the SG to be 1.070+ to get a higher ABV?
d) do you have any other tips on how I can produce 7.5-9.5% ABV cider with OzTops? I don't mind if it's dry.

I actually did taste it and it was still reasonably sweet, it wasn't super dry at all so I'm wondering if perhaps the yeast had died off before it had finished it's job or if I'd done something else wrong. Any tips would be super helpful for a newbie...
Cheers!

 

[decr]

I can't comment on your calculations as I'm too lazy to use a hydrometer, but 1020 is waaay too high. A couple of things come to mind. Were there any preservatives in the juice? What about the yeast, its alcohol tolerance might be really low? At 1020 with simple sugars that sounds like a stuck ferment.

Nothing wrong with pitching more yeast if the batch has stalled. My 23l store bought juice batches ferment all out (yeah, I don't measure but it's bloody dry), I use EC1118 yeast and even that beast takes ~2 weeks to chew through it. I did an experimental batch using coopers kit ale yeast and that took 3 weeks to finish. Smaller batches might finish quicker, the smallest one I've ever done was 4l but even that took way over a week with proper yeast.

Others will be able to comment on your calculations and other points. Hope that helps any.