alt to batt doesn't need a fuse, and neither does batt to batt, but my back battery to amp didn't have fusing so I fused it further up the line, as far as I know, gp's, sunfires etc don't come fused from alt to batt, it goes alt pos, to starter, to batt positive, no fusing, new vehicles do come fused, but its a pain in the ass if you pop that fuse in the middle of the bush or far away from a parts store.