I do more or less the same but i get around 12-14 pints of ginger wine then 2 gal of alcoholic ginger beer from the same must. Put the ginger along with some water, enough so it processes in a food processor, i use approx 1 kg more wont hurt, dont peel just scrub clean. then add water to make a ginger slop of around 14 pints this goes into a bucket with 1 campden tablet, just has insurance against nasties on the ginger, its then left over night sealed . I then add a couple of teaspoons of pectalose and leave for two or three days sealed. then strain off the juice into another bucket , add a kettle of boiling water then yeast nutrient , juice and zest of 2 lemons and 2 oranges (zest not the white pith) or citric acid (this is adjusted at bottling) 4lb of dark cane or molasses sugar dissolved in boiling water couple of pints, and a sherry or dessert yeast ,you should have around 18 pints now ferment for 3 days in bucket then divide between 3 demijohns to finish. possibly add a little more sugar has it ferments, you want a sweetish finish to the wine. Then the ginger thats been filtered off is added to a bucket, with a fresh red chillis mashed, 4lb white sugar juice zest of 4 lemons, make up to two gallons with water yeast nutrient and champagne yeast, ferment for a week in the bucket strain , then bottle into carbonated bottles adding a good teaspoon of sugar and a few grains of champagne yeast to each bottle. then proceed as you would for beer, warmth then cold then drink. Makes a nice fiery ginger beer