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Assuming the 6.4s utilize dual alts the same way the 6.0s do, then according to Ford the computer randomly selects which alt to use. In practice I found this not to be the case. I ran for a while with just the upper alt and the truck charged fine. I then wired the two alts seperately so the secondary (lower) one only went to a 100a charge circuit to my Lance camper. The upper (primary) alt ran the truck loads.
The two alts are different and are not interchangeable. The mounting is different as well. OEM alts are good. Avoid auto part store ‘lifetime’ alts, as you will spend your lifetime exchanging it for a new one. DC Power alts are nice, but are likely overkill unless you have a high charging demand.
Decided to go with autozone parts for ease of returns and warranty.
kept the single in secondary position model
options at autozone was a 120 or 140 amp unit for that position. Bought the 150 amp.
removal was easy
install a little harder since I couldn’t find the belt tension release system.
got it in anyway.
started at 9:30 done at 12:00
inclusive of new alternator be batteries pick up and return of cores.
old alternator was shot pet my meter and batteries did not pass load test.
moral of the story is you either replace your batteries on time when they don’t pass load test or you will wind up replacing alternator as the alternator frys to try to keep weak batteries charged.
i dead to replace batteries every two years and never had to replace alternators even if a half dozen vehicles I had for over 10 years.
truck starts better than ever so I may have been running weak batteries from the start of my used truck ownership.
Ford single alternator to dual alternator conversion
Single alternator to dual alternator conversion
so been researching how to convert from single to dual alternator
so due to the nature of the gen mon and gen com signals its true that the pcm can only monitor 1 generator.
but it turns out that if you unplug the pcm plug from the alternator the alternator behavior changes from smart to dumb. In dumb mode it puts out a constant 13.75 volts. In smart mode it varies the output from 13.75 to 14.5 depending on the signal from the pcm.
so this means you can install the second alternator in dumb mode by not connecting a pcm control wire harness.
so now to test this. Need the new belt and a second alternator .
Make sure the lower alternator is clocked correctly. They are the same alternator but the lower one is clocked differently.
FYI you will also need an additional idler pulley:
I think this is a picture from an IDI OBS truck but it's the same routing as ours (gotta love Google Images).
Budget some time for this. It takes 10 minutes to swap the upper alternator but a lot longer for the lower. Remove the passenger's side fender liner to gain access to the area. It is very difficult to work from the bottom and when I upgraded to the larger 6G case through the side was the only way to go.
There are some drawbacks to this setup besides the obvious labor time and cost. The only way to pull your EBP tube is to remove the lower alternator bracket. While this may not seem overly difficult it is cumbersome and those who have to do this will understand what I'm talking about. Also, CPS replacement becomes a little more confined and tedious...especially if you're doing this on a hot engine while you're on the side of the road.
On the plus side I'm running twin 140A alternators so I'm not at a loss for juice, even at idle.
09-19-2018, 04:57 PM
