I removed and reinstalled my battery the other day to have room to work on other things. Now the battery light on the dash comes on at 2,000 rpm and above. I did my usual wire brush / dialectic prep on the posts and cables during reinstallation. I have a 200 amp alternator, which was installed several months ago, and so far has been fine. Any ideas?

 

Had that on MY E250 started off like at 4500 rpm then 3000 then 800 took a year to go all the way only other sign was I notice the head lights a little dimmer

 

My truck did the same thing after unhooking the battery to change the starter. Over about 3 days, it would come on at progressively lower RPMs until finally the alternator quit completely. While replacing the alternator I had the battery (which was less than 3 months old) ckecked and it was also bad. If I were you I'd have both the alternator and battery checked out. In my experience if one goes bad, it is often because the other is bad also.

 

Per the posts above, my charge light is coming on at progressively lower rpms. I had my battery load tested and it is in good shape. I checked the output of the alternator, and it is 13.5 where it should be 14.5 - 15. It looks like the regulator is shot. So, repair or replace. It is under warranty, but has to be shipped...what a PITA.

 

I really don't know too much about the internal workings of alternators. I do know that in these trucks the voltage regulator is a part of the alternator and I don't think you can buy a regulator separate. I also don't think the voltage regulator is your problem. I believe all that does is make sure the alternator doesn't put out too MUCH voltage. I think the brushes inside the alternator probably are worn out. But like I said, I'm not really an expert on the subject so you're going to want to do a little more research before you make a decision. I think I would take the alternator to an automotive electrical shop and see what they would charge to repair it. Then you just have to weigh the cost of fixing it against the time it would take to get a new one through the warranty.