Voltage Fluctuations and intermittant Battery light
Been fighting this battle for a while in some form or another...long story but you can see what all has been done.
maybe 2 years ago, noticed this problem under load initially, and then once in a while at idle. Batt light would flicker on and I could see headlights slightly dim most noticably when I stomped the gas.
everything tested/checked good (belt, tensioner, pulleys, wiring, alt tests)
gave up and shotgunned an alternator in (from Oriellys). seemed to have done the trick for a while. Prob came back after a couple months, not a real big deal as I didn't have any charge probs and drove fine.
Winter came, killed my batts. Replaced both with Optima Red Tops.
prob still there on occasion but rarely. Hard to chase down due to being intermittant.
Over the year I'd see the light come on but seldom, mostly only at night with all the lights on.
Moved up to NC this past fall and pulled my Jeep. Changed belt, oil, and cleaned and tightend all connections prior to the trip. Wife drove the Ex while I drove the Penske. she calls me and say the light is getting worse and her headlights are going in and out. I confirm by seeing her headlights dimming a bit. We call it a night and shut down. Next morning check everything out and all is well. I think maybe the alt is getting hot and cutting out. Proceed to drive the rest of the way with no issues (daytime- no heater, lights, A/C).
So after we get settled I look into the issue again. I notice the new belt is shiny and has some wear so I order another one along with a tensioner from RockAuto. Noticed the cheapo belt I had used as a replacement prior to the move was about 2" longer than the motorcraft belt I had just bought. That would prob account for the shiny worn belt and possibly some of the issues.
So I changed out the belt and tensioner and everything is grand until my wife calls at work a couple weeks ago and wife says the light is back. No big deal, she goes and does her thing. I go out to start the truck yesterday evening as we get ready to go to church and the batt light is on flickering but mostly on at idle, door open lights are really flickering, and the battery guage is all over the place (down to as low as 8 and as high as 18-20). I didn't drive it and am about to go to parts store this morning.
Hopefully the prob will show when I go test it again.
I'm prob going to see if I can find the charge circuit harness for my own piece of mind though it meters good.
I'm headed overseas and momma needs this thing to work!