You just have to weed through the BS and listen to the people who make logical sense, I think about 90% of the people here got it right.

With regard to the jumper wire, you’re correct. If you hadn’t done it that way, then the your original link would need to be replaced after the first time you started the car with a dead battery. There is one caveat though, and that’s that if you are going to split the current through a pair of wires, the length of the wiring needs to be fairly close. Copper has got a positive resistance coefficient, which helps, but if one of the wires is significantly shorter than the other, than the lower resistance of the shorter wire will cause it to carry more current than the longer wire.

With regard to where to connect the relay, steveg75 gives a good explanation as to how and why it should be done that way, the problem being that the alternator will see the current spike of the fans when they turn on and load dump when they shut off. You can get away with connecting it to the alternator using relays, but it’s not the best way to do it. As far as the battery not charging, 30A through a pair of 10 gauge wires of that length results in about 1/10 of a volt drop across the wiring. Given that even the factory GM regulators are specified to be accurate within ½ a volt range, it’s hardly significant.


Try again genius