The problem with that argument is that the “bigger” rotor is from a 12v alternator, the “smaller” rotor is in a 48v alternator.

the jump from 14v to 56v is 400%, the jump from 48 to 56v is 16%.

I can’t buy the argument that to go from 48 to 56v you need a rotor from a 12v alternator because the 48v one can’t handle it.

It’s also arbitrary to claim to know the exact difference in these rotors they could just be a different coil finger shape. The manufacturer themselves say the 48v and 56v alternators are the same save the regulator. The manufacturer doesn’t view the rotors as significantly different. It could be as simple as a minor revision.

 

I respect the guy I’ve been conversing with lately but here is the problem with his facts.

I asked him if he could/would take ohm readings of the parts and to take an A/C reading of the output. He doesn’t want to. That’s fine. But we don’t know if the rotor was defective because he wouldn’t test it. We don’t know if they capacitor was causing the overheating because it was defective or if the diodes are going bad and the capacitor is creating a short circuit.

his diagnosis was guesswork with parts swapping. He got it working which is awesome but he doesn’t actually know what the problem was.

I tested my alternator voltage with a drill after my regulator swap and didn’t have the issues he had with overheating or low voltage. Same alternator, same regulator, factory rotor. I have not load tested it due to my diesel not having a muffler and I respected my apartment neighbors enough not to run it for testing. Now it’s in storage it eventually when I get the new house I’ll post my results of a load test, good or bad.

 

The problem with that argument is that the “bigger” rotor is from a 12v alternator, the “smaller” rotor is in a 48v alternator.

I wasn't saying to use a 12V rotor. Just gave that as an example of how a rotor works. That regulation was by a fraction of output voltage, only the amount needed to create the necessary magnetism.

But somewhere in the not too distant past in this thread, one of you was talking about 12V being needed for this. Or I misunderstood what was being said.

 

The rotors in the 48v and 56v alternators are also used in 12v alternators. This is a real world issue with real world parts not an intellectual exercise. We are talking about 12v rotors. The field cools are fed 12v even though they are not 12v alternators.

 

I just take issue with saying the manufacturer is wrong, that the rotor must be swapped to get 16% more voltage. No tests have been reported on the diodes, rotor, or capacitor. Diagnosis by swapping parts leads to situations where you’re not sure what the real cause was. Especially when you install different models of parts without first swapping in a know good exact replacement. (A known good 48v rotor was never put in). We aren’t even sure if the capacitor was the real problem.

 

I don’t want to bash the guy, and I apologize if that’s how it sounds, but to have other people read this thread possibly years from now thinking that they need to swap parts when a full diagnosis was not performed is irresponsible to the community.

 

the jump from 14v to 56v is 400%, the jump from 48 to 56v is 16%.

Not trying to argue but just to learn/expand my knowledge. Your saying a 48V stator is the same as a 56V one? I didn't know you could get higher voltage from an alternator by without increasing the number of turns of wire in the stator. It's my understanding that the number of turns increases volts, and the guage of wire increases amps.

The field cools are fed 12v even though they are not 12v alternators.

So your saying there has to be a way of supplying 12V and have 48/56V too? Again, not trying to argue but learn.

 

The stator is fed 12v on these alternators.

the manufacturer themselves say there is no major difference between the 48v and 56v alternators besides the regulator which can be interchanged between them.

these are not like car alternators where they can stand alone independent, they require an existing 12v system to be used.

starter motors almost always are 12v, it’s reasonable for the manufacturer to assume there will be a 12v system on the motor anyway so it’s not a negative really.

 

Just happened to come across this and want to mention we make adjustable voltage and amperage control kits for these 48V alternators.

 

Who is we? A google search of your profile name doesn’t come up with anything