3G alt. with external regulator?

[Broncobowsher]

I've heard of plenty of issues with the battery selector switches over the years. That wouldn't surprise me.
Where do you have the "sense" wire hooked to? Try the battery itself. That way the regulator can actually see battery voltage and not alternator output voltage.

 

[ntsqd]

I need to look at that. I don't recall moving any of that, but I could have as I did that work almost 3 (?) years ago. Everything battery cable-wise on the truck was about to age-out, so I made new cables. Carolprene 1/0 welding cable, Greenlee hex die crimper, adhesive HS bridging from the jacket to the lug. The selector switch is Blue Sea Systems part.

 

[Broncobowsher]

I was saying that because the typical retrofit install is just loop the sense wire to the alternator output. But if you have losses in the cabling it would help explain the not full charge you are seeing. And why Ford put the seperate sense wire from the regulator to the battery, to see what is really happening at the battery. Although now that I think of it, there is nothing to account for losses on the ground side. But a battery cable directly to the block should be pretty good.

 

[ntsqd]

Wasn't just Ford that did that, but like you say, most alt. upgrades or conversions just loop back to the positive stud on the alt. This does have the E-250's 130A alt. on it in place of the stock 90A or 95A, but I left the wring for it alone after deciding that the charge wire was large enough for the higher output alternator.

As I recall the stock ground cable (this is a '96) had a mid-span tab in it that grounded to the chassis before jumping across to the engine block. I duplicated that, but with separate cables. Even the Aux battery is grounded to that same chassis bolt.