by skilletky » Tue Aug 20, 2013 6:49 pm
The battery voltage wire going to the regulator goes through a few fuse able links and connectors. Being an old truck , there is quite a bit of resistance in the wiring. By time the volts get to the reg, it may have lost a volt or 2. So if your alt is charging at 13.8 volts , and you loose a volt or say 2 volts at the reg, it thinks its only charging 11.8 volts. Now it's gonna "ask" the alt to charge more until the reg sees let's say 13.8 volts, when really the alt is putting out 15 volts. The relay gives the voltage reg a "clean" battery voltage. As far as what kinda relay to use, I just used one I found at work.
92 d350, arp's, orings, 150lb springs, 4200 gsk ,ground pin ,64/71/14 ,ddp inj's, ats manifold, tim's tubez, ats trans, FASS, locker, timing + a tooth, bcdd intake
2001 2wd rclb dually 5sp, smarty, Bluechip FMS, TS MVP, 57/75 twins, stainless diesel pipe kit, valair clutch, airdog 150, DFI SAC 7x.014's, cheap a$$ intake, ARP studs, oringed head, CPP 115# springs