Alternator wiring - where do these wires go??

[HRK]

1980 Aristocraft I/O - 2.5L mercruiser engine. I attached a photo of a large harness connector. Coming out of this connector, are all of the wires that run to the front of the boat - dashboard, bow light, breakers, etc. I removed and rewired everything forward of the engine (left all engine wiring in-tact). Everything is functional, EXCEPT I can't get the alternator to charge without it bogging the engine.

I have three thick wires coming out of that connector - thick red, thick black, and thick orange. Black is ground. Continuity test tells me that the orange is from the alternator BAT terminal, and the red is from the S (sensing) terminal. However, when I connect both to Battery positive, the engine bogs immediately and idles rough - almost like it's down a cylinder. It revvs up fine, and charges fine, but idles like crap and the alternator gets crazy hot to the touch (not sure how hot is normal). If I disconnect those wires, it idles beautifully (but doesn't charge the battery obviously). Tried hooking up a dummy light between the sensing wire and battery terminal (like a dashboard idiot light), but it doesn't light up with ignition on / engine off like it's supposed to.

Alternator is brand new - actually my second brand new one. Battery and coil also brand new. Coil is getting proper 9V through a ballast resistor.

Any ideas? I'm assuming it's not normal for the alternator to create that much drag on the engine, so I'm completely stumped. Would love any thoughts. Here's the connector I'm referring to:

 

[bruceb58]

Show us where you are connecting these wires on the back of the alternator.

 

[HRK]

I don't have a photo of the alternator wiring itself, but it's part of the factory harness - the entire engine harness is un-touched. So it pops out of the harness at the alternator as an orange and red wire, and the other end pops out at the large connector in the photo as an orange and red wire. The large connector then goes to the front of the boat. That connector is where I have a thick orange and thick red wire. The diagrams show them going to the dashboard ammeter gauge and power distribution block in the dashboard, and then back to B+. So I'm just bypassing that step and going straight to B+, but obviously something is amiss.

 

[HRK]

I'll also add, I tried wiring the alternator direct to the battery, bypassing the entire engine harness. BAT terminal to B+ on battery, S terminal to idiot light and then to B+ on battery, and exciter wire to coil. Exact same problem. So I guess my real question is, what's causing the motor to bog so heavily as soon as an alternator is hooked up to the battery?

EDIT: Now I'm reading that many alternators do get very hot when in "bulk charge" mode, and calm down when the battery gets close to charged. Maybe I'll put the battery on a trickle charge and get it fully charged, then see how the alternator behaves.

 

[GA_Boater]

HRK - Moved this thread out of the the Electrical section. This is specific to Mercruiser wiring. Also deleted your same thread in the Aristocraft section, again because this is an M/C type of question.

 

[HRK]

Thanks! Sorry for the inconvenience, new to the forum stuff.