The alt wire is a 8AWG resistive wire for safety. If the diodes ever go out in the alt, the wire is supposed to burn up instead of draining the battery. Dead battery or wire on fire, you take your you choice. It can only carry about 50amps from your 100-135amp alt. I added a 4AWG wire from the alt (+) to the (+) battery and from the (-) battery to the chassis for ground and now everything works much better.