1994 K3500 extended cab dually

[n8in8or]

Yeah, they're the same size pulleys. I'm not following how they could be fighting each other if they weren't spinning the same speed.....

 

[dbrannon79]

the higher RPM sometimes can allow one to push more amperage. something I was always told when running dual alts that each having their own built in regulators. iirc for them to work properly they would need diode isolators. I don't recall all the details though

 

[n8in8or]

the higher RPM sometimes can allow one to push more amperage. something I was always told when running dual alts that each having their own built in regulators. iirc for them to work properly they would need diode isolators. I don't recall all the details though

Hmmm..... I'm not sure that's rectifying in my brain (pun maybe intended), at least the amperage part. I doubt 2 production alternators on a dual alternator setup are capable of outputting the exact same amperage, not to mention if one fails and gets replaced with an aftermarket replacement. But more importantly, I think of amperage in this situation as being a pull, not a push, and it's just the alternators ability to feed that pull or not. If the alternator isn't big enough, then it can't satisfy the need all of the accessories in the truck are asking for and that's when you see lights dimming and such. So in my mind, the alternators are only putting out what is needed, and not forcing juice into the system beyond what is required, and so in that situation, I can't picture them fighting each other either as they would both be just sending their power into the cable.

I was going to say that I could maybe see a diode of some kind being needed, but then I believe that would counter my statement above about pull vs push, so I'm also thinking that isn't a thing. I was curious, so I just looked at the RockAuto catalog to see if it had listings for alternators in single or dual applications for a 1998 K3500, and it didn't say that. I also tried looking at a GM catalog for a 1998 K3500 and it only listed the alternators with 3 amperages, and not if it was single or dual alternator. I looked up both a 1998 and 2002 C3500HD to see if there was anything for single or dual alternators since it would be more common in that application, but unfortunately they don't even list the alternators at all for those.

I was able to grab the harness from the truck I removed the brackets from and I didn't see anything like a diode or anything in the harness - it was just a harness that plugged into the main harness and joined the plugs of the 2 alternators together. There didn't appear to be any more magic than that.

I could be wrong, and maybe I'll find I'm wrong when I go to wire these up and consult the wiring diagram in the factory service manual, but so far I don't see any evidence that makes me concerned about the alternators fighting each other in any way. I'll definitely report back if I do though.