A charging question

[mjs2011]

I was going out with the camper yesterday, got half way to my destination, and shut the truck off. It wouldn't start when I got back in, so I got it jumped and went on my way. When I got there, I unhooked the camper, went to start the truck back up, and it wouldn't start, the battery was completely dead. So I charged it all night. I just so happened to have a Honda Generator with me, that comes with an 8A battery charger cable. So I rigged that up to keep the batteries charged up to get me back home today.

I started looking at things and found that I am seeing no voltage change at the battery whether the engine is off or running. The voltage is always about 12.45 V. So I disconnected the positive terminal on the alternator and jumped a wire from the pos term on the alternator direct to the battery. Still no change. I then checked voltage at the positive terminal on the alternator, with ground on the battery as reference. This voltage was between 2-3 volts at idle. So I pulled the alternator out. Some pictures are attached.

A few things I've noticed: The ground terminal of the alternator has no wire on it, just that metal tab. I'm guessing it's been this way for years. But is that normal?

Also, I pulled the alternator, and set it up on the workbench. It spins freely, but makes a slight bit of noise as it rotates, and if I look from the top down on while its rotating, the pullys are rotating perfectly balanced.

My main question is, is this for sure an alternator problem, or are there other things I should investigate first?

 

[Wvdirtroad]

If your battery is not charging while running it's usually always an alternator problem. I would try putting a charged battery back in and turn on all your electronics etc. if the vehicle dies while running it's definitely a alternator issue. I think some places also load test them. I know on my IDI when I touch a voltmeter to the back of the alternator I hang around 13.5-13.8.

 

[mjs2011]

Well, the truck never died while running, but if I shut it down, it wouldn't even think about starting. It barely turned over it was so dead. I just want to be sure that its alt and not voltage regulator. I think my regulator is external, mounted on the inner fender well. I guess I'll see if I can get my LAPS to test the alternator for me. Advanced Auto or NAPA, anyone have any preference between the two?

 

[laserjock]

It could be the voltage regulator. Remember, it takes next to nothing to keep these things running if you are on a mechanical fuel pump. I think Gary (icanfixall) says like 9v to hold the fuel shutoff solenoid open. That's really all you need.

You could have a bad battery, alternator, regulator, or connection that might cause that.

 

[G. Mann]

You need the ground wire on the alternator. Without the alternator being properly grounded it doesn't complete the charging circuit, I believe.

One of the wires on the two wire plug that goes to the Alternator should have 12 volts when you turn on the key.. I believe that 12 volts then energizes the stator coils which make it "alternate". With the ground wire broken off, could be it's been finding ground some other way, and has now lost that connection. ??

Some years ago, I was advised by a long time ford mechanic to run a second ground wire from the voltage regulator mount screw to that alternator ground lug, just to be sure. I did, and I think it's a good idea.

Anyone here have other ideas? I could be off base on this..