Recently I've noticed my battery indicator light will come on at about 2400rpm and then go back off after dipping below 2400rpm. The longer I drive it seems to come on at lower rpm (2100rpm after 30mins driving). Anyone know what could be causing this? Battery is approximately 1yr old. Alternator not meeting demand at higher rpm?
Thanks in advance!

Forgot to mention...1999 F250 LD.

Oops...I'll repost in electrical.

 

You have a bad alternator

 

My truck did this too. It worked that way for about 3 months, then the battery light stayed on all the time.

It was the alternator.

Replace it before it leaves you on the side of the road!

 

It'a an alternator.
Do yourself a favor - intall a new one. You don't want to sit in a stalled car.
Alex.

 

Small addition to the previous post.
In my case I had like an hour between the battery went off and the battery went dead without an alternator. I was towed

 

I don't understand, everybody says REPLACE THE ALTERNATOR.
I had a truck just like yours, and had the same problem, but instead of blowing $200.00 or more on a new alternator, I checked the brushes in the internal regulator first, and that's wherein the problem was. It's a very easy fix, and since you're gonna pull the alt anyways, it only takes another five minutes to check the regulator(which is bolted to the back of the alt and held on by four small torx screws). New brushes are only about $15.00, so do yourself a favor and check, now with that being said, it could be a fried alt, but it doesn't hurt to check and possibly save a few bucks.

 

Well you thinking a bit narrow.
It is the alternator.
Many people won't touch the unit, so they have to replace it!!
But good for you.

 

Huh or should I say eh? I didn't say it wasn't, I just mentioned it could be a component of.

 

Our Battery Light just came on this morning. I got a new battery 8 months ago. I have the original belt on there 60K miles. Should I try and change that first, or should I get a new alternator too?

 

Go somewhere and get a load test done. A load test will test both the battery and alternator. Just b/c a battery is new doesn't mean it's good, and if it is the battery, at least you will still have warranty. Also, if it turns out to be the alternator, do yourself a favor and check the regulator, it can't hurt. This thing is what determines voltage output anyways. As far as the belt goes, it wouldn't hurt to change it out, they're not expensive.

 

I took off the alt. and had it tested. It was only pumping out 10 volts. The voltage reg. and the stater <sp> were both bad.
I bought a reman with a life time gar.
Pretty easy job really. Like all easy jobs I found ways to make it hard.