My 4 gauge wire install and more related information.I left my original plug wires intact and still use the existing wires in parallel to the new 4 gauge wire installation. The highest charge voltage I would get on the factory wires was about 12.6 volts. With the new 4 gauge wire, I get up to 14.2 volts on high idle and 13.9 volts most of the time at the TC batteries. I wired the new 4 gauge wire directly to the alternator as it eliminates about 9 feet of wire if the positive is wired direct to the truck battery. Length of wire is the enemy. Look at my install above. Should give you some good ideas. The 4 gauge continuous duty solenoid is powered by the activate wire for the factory cube relay to charge the TC batteries. The wires are both in use and in parallel. More wire = thicker wire and better conductance.
