Alternator/Battery Charging issues

[Waterproof]

Okay, here is my issue. My truck died while idling when I was letting it warm up. Went to start it back up and the batteries were totally dead, now keep in mind it started up perfectly 15 minutes or so prior. I figured my alternator went out, pulled it out took it to the parts store and it tested bad. Replaced the alternator, charged the batteries up for a while from an external source, started the truck back up and it ran fine for about 10 minutes or so and died again. The exact same thing that it did prior to me replacing the old alternator with a new one. Called the parts store back up and had them re-test the original alternator which now tested good twice. Took the new alternator back to the parts house and put my old alternator back in the truck. Replaced the regulator plug with a new one per the parts house suggestion. Truck seemed to run okay for a while. Now here recently the truck started acting up again doing the exact same thing. Replaced the alternator AGAIN, replaced the batteries with Two brand new batteries, and guess what, it is still doing the same thing. My truck is out of warranty even though it only has 89,000 (thanks Ford for the 5 year time limit) and shy of putting a stick of dynamite under it, what should I check to see what else it could be?

 

[BIG JOE]

Bad Ground. Bad Battery Cables. Bad starter. Dead short.

Tell us a little more 'bout yer truck. 07 ? any Mods ?

 

[Waterproof]

It is a 2005, no mods at all.

The issue doesn't appear to be anything to do with the starter as the batteries die when it is running (alternator not charging) and then the batteries are so low that it can't do anything but click-click-click-click when I attempt to start it.

I have metered the voltage off of the alternator and it jumps around from 11.2 volts to 13.8 volts. Same voltage reading at the back of the alternator and at the battery, so I don't think it is the fuse link on the alternator cable.

 

[snicklas]

Have you had the batteries tested? I had a problem with mine not charging. Thought it was the alt, replaced the alt 3 times... they kept going out. After the last changeout, a buddy who also has a diesel (90 IDI). One shop tested the batteries as bad, another as good. So we swapped batteries. Mine was fine. A couple weeks later, he was having starting issues. In troubleshooting we found the pass battery (same location it had been in my truck) had failed and actually swapped polarity. If you measured the voltage, it was a -9.7 volts with the pos on pos, neg on the neg. It did some wiring damage on his truck, and popped the glow plug controller. I would say have the batteries checked or replace them.

 

[Zmann ARGH]

My truck is out of warranty even though it only has 89,000 (thanks Ford for the 5 year time limit)

that was only covered under the 3/36

 

[Waterproof]

The batteries are less than a week old, I replaced them last week the day after I put the new alternator in.

Have you had the batteries tested? I had a problem with mine not charging. Thought it was the alt, replaced the alt 3 times... they kept going out. After the last changeout, a buddy who also has a diesel (90 IDI). One shop tested the batteries as bad, another as good. So we swapped batteries. Mine was fine. A couple weeks later, he was having starting issues. In troubleshooting we found the pass battery (same location it had been in my truck) had failed and actually swapped polarity. If you measured the voltage, it was a -9.7 volts with the pos on pos, neg on the neg. It did some wiring damage on his truck, and popped the glow plug controller. I would say have the batteries checked or replace them.

 

[Waterproof]

Thank you for that correction, do you have any thoughts on the REAL issue of my original post or just wanted to make sure I realized I stated the warranty coverage wrong for the alternator?

that was only covered under the 3/36

 

[Zmann ARGH]

I wanted you to feel more comfortable about missing the warranty coverage for the charging issue for one.
My first take is the alt is fine if it is charging like you tested at both the alt and batt terminals ,, you did state you replaced the batts also and have the same issue
so I am a little lost with your problem
i still suspect a poor connection or a diode issue

 

[Waterproof]

I didn't mean to reply with the tone that I did, I am just frustrated with this stupid thing and and really needing to get it figured out.

 

[W4RLR]

Bad ground and bad cables. Had the same problem with the wife's E-350 van with a 6.0 diesel. It was a pain in the arse to trace down, but that's what it was in our case.