charging issues

[dentexpowerstroke]

I'm stumped on this. Batteries died on friday, I jump started it and let it idle a little bit to warm up. I walked back out about 20 minutes later and the truck had died, so dead it wouldn't jump start again. Batteries had got down to 11.5v. I got the truck home and charged the batteries, tested the alt and it showed it was only putting out 11.5v. Saturday I started messing with it and the alternator was putting out 13.8. Drove it today and checked it with the live wire and it's back to putting out 11.5v. What would cause the alternator to intermittently drop to 11.5v? When I had it tested about 2 weeks ago it tested good, batteries are still testing good. It's normally at 11.5 when the glow plugs are on and then kicks to 13.8 but now it just stays at 11.5. Any ideas? I've also had a couple guages on the cluster freak out lately so I'm starting to think it may be a bad cluster causing all this.

 

[Slate]

I had an issue with my 7.3 where the alternator was only putting out 11.7v. My issue was my GPR was drawing 80amps anytime the key was one. It was stuck open. I would test the amps to see if your drawing too much from somewhere.

 

[Mdub707]

Just for whatever it's worth, it seems the alternators don't even run until the glow plugs go off on these. Mine are usually sitting around 11.5 all the time with the truck off or with the truck on and the glow plugs on, once they're off and the alt kicks on, it jumps to 13.8-14.2. So you're saying you're seeing it at 11.5 while driving down the road sometimes now? To me, that says the alt isn't charging.

 

[ghohouston]

Id bet the cluster gauges acting up are from the alt not charging. My 7.3 would **** the entire cluster down on extremely cold mornings, like I was telling you about how my alt acted up when REALLY cold

 

[Mdub707]

Good point, any time my batteries were dead and I tried cranking, the gauge cluster freaks out.

 

[dentexpowerstroke]

Yes driving down the road it's at 11.5. It's weird that it's right at 11.5 because that's where it is when the glow plugs are on. Is it possible for the gpm the mess up and leave the glow plugs on.

 

[Trqmnstr]

Every alt ive dealt with never just died, they would charge good one run and bad the next. Got sick of pulling them only to have them test good then reinstalling only to have them shyt out 2 days later.

Eventually i resorted to just swapping out for a new one when i had the problems your having.

Of course this was back when i drove POS trucks with $150 alternators. Lols