A charging system upgrade I did on this beautiful Dave Harris tug with sweet 30hp Sabb 2JHR engine.
Original alternator was a low output Motorolla. I fitted a 110amp 12V marine alternator with custom 60mm XPA pulley, 50mm cables; Adverc system; Victron BMV700. Replaced 3 * 110ah domestic batteries with 4 * 6 volt Trojan T105’s. Installation has transformed the domestic charging system. Excellent output (50 amps) at tickover.
On this job I fitted a extra small 60mm pulley which I’ve had made. Using a smaller alternator pulley reduces belt contact area and puts more heat into the belt. You have to use Gates XPA Quadpower belts and it’s a compromise between belt life and alternator performance at lower engine speeds. Smallest pulley size you can go down to is 55mm and generally I fit 65mm.