Alternator Cutting Out

[gamefanatic]

So a while back I had to limp home almost in the dark because my Alternator quit charging on the way home.
I did the typical, oh its the Alternator, without diagnosing. After replacing the Alternator with a new one, I found it still wasn't charging. This time I started probing and low and behold the 30 Amp fuse had blown.

Now she's charging again, until I hit about 5200-5700 RPM. The battery light starts to flicker and voltage drops to ~13V at least until it shifts. Now that I have a strong fuse, I know the root problem was not just a fuse...

I don't hear any squealing at the time so, not sure if its just a belt.

Any suggestions on how to go about diagnosing this as it only appears to be a problem during that rev range and was likely affecting both the old as well as this new alternator...

 

[E1]

LOL

You got a regular Windstar Alternator.

It fits, it works, but it has the less expensive low cycle speed diodes in it. Once you spin it up too fast they can't keep up and just stop working. Bring down the RPM's and all returns to normal.

I wouldn't worry about it too much unless you spend more than 15 minutes at a time over 5500 RPM's.

 

[gamefanatic]

Well, I know the old one was not, but I will double check the new one. I could see the contactor bouncing around being a problem or the voltage regulator. If its wrong its a lifetime warranty, so I'd just take it back.

 

[SHOZ123]

Make sure the pulley is the same size as the original. The SHO took a special size and most aftermarket don't give you that.