Bad alternator or something else?

[00XLS]

Yesterday I replaced my battery, which I think was stock because it was a motorcraft brand, with a diehard SUV.That battery wasn't dead but on really cold morning, around 5* it took a bit long to start so I figure I'd beat that out before I found it dead. But anyway,last night while driving I had the heater on full blast normal electronics on and when I came to a red light my voltage gauge dropped almost to the line. Once I started going again, lights brightend back up and the gauge went to the middle. Is my alternator dying out? Anything else could explain this ?

 

[Glen4X4]

Kinda sounds to me like an alternator if you've replaced the battery. Although are your battery terminals pretty clean that the bare metal is touching the battery posts? Sometimes even cleaning them don't do the trick that replacing the whole terminals will help.

 

[00XLS]

I cleaned the battery terminals with a wire brush, the looked to be bare and clear. How difficult to replace those?

 

[Glen4X4]

Well I too have done the cleaning with wire brush and seemed to have low voltage sometimes so I had replaced the terminals and lights were brighter, they didn't dim when say the heater was on high. It helps to have a wire stripper or wire cutters to cut off the old terminals then use a knife or wire cutter to strip some plastic off the cables, the terminals usually come with a clamp and two bolts so all you should have to do is strip the rubber off the cables and put the cable on the terminal and tighten that clamp so the cables are snug on the terminals, not hard. They may also come with a green and red fiber ring, they are suppose to help fight corrosion they slide down the post and sit on the battery.

 

[00XLS]

I'll take a look at that, I tried those fiber things and the one ripped as I was putting it on, useless in my opinion. Thanks for the imput, any other ideas?

 

[Glen4X4]

Its deff. a power issue that I suspected as the alternator, (thats what I thought was wrong with my truck) so I replaced the terminals first since they're cheaper than an alt. If that don't help then I'd deff. look into the alt. depending on the miles of your truck it could be reaching the end of its life.

 

[Pensa]

If you have an Auto Zone nearby have them check it out. They do it for free.

 

[Glen4X4]

I don't think there's an autozone in State College is there? Just pepboys and advance auto that I can think of.

 

[00XLS]

I'm in Frackville right now, we have one fairly close, can they do the testing with it in the truck, or would I have to take it out? BTW the truck just turned over 97K, so its prob on its way out.

 

[Glen4X4]

When I seen commercials they always had the alt. in hand on a machine in the store.

 

[aldive]

What is the voltage at the alternator when ideling? at 2000 RPMs? What is the voltage at the battery when ideling?

 

[00XLS]

I'll check into that and get back to you.

 

[Pensa]

Auto Zone will check it in car, no need to take it out and take it to them.

 

[aldive]

Auto Zone will check it in car, no need to take it out and take it to them.

All he needs is a voltmeter to check the voltages.

 

[Pensa]

True, but I think their equipment will put a load on it and see if it breaks down under load. A simple volt meter test wouldn't show that up.

 

[aldive]

If it were mine, I would be more concerned with the voltage at this stage in the diagnostics.

 

[Pensa]

Re-reading the original post this problem seems to only have shown up since he changed the battery. I would suspect something other than the Alternator. A dirty cable or bad ground maybe.

 

[00XLS]

I cleaned both contacts with a battery brush. I simulated last nights circumstances and it didn't show a drop or anything, might be a fluke but I'm going to get readings on it tomorrow and see where we're at.


Thinking ahead, any brand of alternator to stay away from? I seen advance has a 130amp for a decent price.

 

[aldive]

I would recommend going with the 130 amp unit.