Low charging issues

[slyhog022056]

91 ford f 350 7.3idi
Having charging issues, first installed a rebuilt 70 amp alternator 3 months old, then 2 different new electronic voltage regulators, all 4 batteries have tested good, only 1 year old. When i run my a/c or headlights or led light bar i have very low voltage, my turn signals wont work at idle ever with a load and have to put truck in neutral and rev engine up to about 1200 just to get voltage regulator to begin charging. When i start it up i the voltmeter swings between half way to about 3/4 way at the rate of about 2 times a second for about 30 seconds. this is before adding any load. once i turn on any load like compressor, s/c, headlights etc it swings until i get above 1200 rpm. I have checked for loose wiring, corroded connections, wiring from alt to voltage regulator. all my batteries are wired with common positive and common negative with 2 grounds going directly to engine and 2 grounds fron engine to frame and body. all are 1/0 wire with all ends silver soldered on, top bolt lug style batteries1180 cca each. anyway i can seem to figure out why this thing wont charge right at idle. I wanted to swap the alternater out under warranty but oreileys wont let me do that as long as it test out ok. Cant seem to find a manual voltage regulator anywhere.
Any suggestions from anyone??? I cant seem to figure this one out other than getting a 1 wire alternator and starting all over.

 

[Dieselcrawler]

just swap to a 3g alternator. simple to find in junk yard and pretty much a bolt on. they are 130 amp.

 

[franklin2]

We need real voltmeter readings on the battery when you do your tests, not the ones from the dash gauge. Take a reading also on the battery before you start the engine to give a baseline before the alternator is turning.

 

[slyhog022056]

ok, got 12.8 at the battery all the way back to alternator terminal not running. runnning i get 13.2 all the way from alt to battery at idle. rev to 1200 rpm i get 13.2... but then i found the problem, got to poking around wires and harnesses and suddenly it jumped to 14.6 so i tried to trace it out and ohming every wire couldnt find a problem. then i unplugged the field wires from the alternator and i am damned if the field terminal in the alternator wasnt connected to anything. flashlight in hand i saw that the wire in the altrernator that was supposed to be hooked to the terminal had come loose and was intermittently making connection. pulled alt and regulator and went to get a warranty replacement.
I am just glad i didnt ruin 4 batteries and had the knowledge of electrical. sure woulnt have wanted to pay someone to troubleshoot it.

Thanks folks appreciate the help.. now .. onto the cracked injector line problems