130A Alternator?

[8thTon]

While reassembling the engine after a timing cover gasket replacement (3.0) I took a look at the alternator - it's about at the end of its life with not much left of the brushes and big grooves worn near through the slip rings. Given how easy it is to replace I'm going to get a cheap replacement, and I see a 130A unit on RockAuto. I suspect mine is 95A. Is there any reason I can't use that?

 

[85_Ranger4x4]

Check the mountings and connections.

 

[RonD]

No, no electrical reason not to use a higher rated alternator

An alternator only generates the AMPs needed by the vehicle when engine is running
So if electrical system is stock the 130amp alternator would only ever get to about 60amps with all electrics on, so wiring from alternator to battery doesn't need to be larger gauge

If you are going to add more electrics to the system then you may need to change to larger gauge on the B+ to battery wire, or add a 2nd wire with fusible link

Stock Alternators are rated at about 35% more than max amp load of stock vehicle, this is because an alternator can only generate about 65% of its rating at engine idle RPMs
If one of the three Fields in an alternator fails you will see dimming lights at idle, because you have lost 1/3 of the capacity of alternator

 

[Eddo Rogue]

I tried upgrading to a 130A alternator. I purchased the Bosch unit from Rock auto. It blew in 300 miles. I went back to my old stock 95amp Motorcraft, which I thankfully had saved.

 

[8thTon]

My simple ranger has very little electrical load, so it's probably silly to use a higher output alternator anyway. There's only lights, blower fan and engine, not even a defroster.

 

[85_Ranger4x4]

Defroster?

A/C delete truck or what?

I have a 130 on mine, it is way overkill but works fine.

 

[Eddo Rogue]

I wanted it for when I switch to electric fan and maybe add some more lights or sound.

 

[8thTon]

Defroster?

A/C delete truck or what?

I have a 130 on mine, it is way overkill but works fine.

Sorry, I meant an electric rear window defroster like on many cars - one of the bigger electrical loads, but of course a truck doesn't have that.

 

[8thTon]

I decided to get the cheapest "Valuecraft" 95A off the shelf at AZ this time. I want to put it in now while I'm working on it even though I could run this one a little longer.

Interestingly the only thing wrong with mine is that the very narrow brushes cut clear through the slip rings. I've never seen that before. If it had been a higher output unit with fatter brushes that had more surface area I bet it would have lasted longer. Still, it made 130k miles and I guess that's good enough.

 

[8thTon]

I put the cheapo alternator on and it works fine. Time will tell how it holds up but I'm happy with it so far. It appears to have been rebuilt in Mexico and uses a Motorcraft regulator. They supplied it with an output performance plot which I liked: