My answer to that, Bill, would be that, before hand, they probably were getting less than 11 volts ... tired wires, poor connections, long wire runs that lose voltage because of distance, etc., etc.
I ran an 8-gauge wire from my battery's +-terminal to terminal blocks on my firewall and powered my fuse box, headlights and electric fan directly from that source -- and my alternator reads that source (instead of the usual BAT connection), too.
That, along with the use of relays, makes a very big difference. The truck runs better, too!
See Here
