32v Alternator Wiring

[sixty]

I have been having alternator issues on both12v71ti engines since I bought the boat and could never get them working. The alternators that came with the boat only had one insulated terminal so I assumed they were one wire alternators. I finally bought these new alternators from rare electric which should be the direct replacements however they have two large insulated terminals. I installed the alternators but cannot get them to charge. I jump both terminals and get a little spark but still no charging. I have run the engine rpm up with no difference. I have full battery voltage at the alternators and solid grounds so that shouldn't be the issue.

I have reached out to Rare electric but don't expect to hear back form them over the weekend.

Any ideas on the wiring or where to check?

 

[SKYCHENEY]

Do you have the Hatteras wiring schematics?

 

[Captain Ralph]

Your picture is of the original Delco 30SI. Probably the back bone of 32Vdc alternators on Detroit 2 strokes.
What a work horse.
The two large terminals are negative and positive. The case is not tied to ground / negative.
The two regulator spade/blades should be tied together just inside the square opening and read battery voltage on both when not running. When tied together, no loose wire should be on them.
If they are not tied, one post will have to be connected battery feedback.

I have the same on my 12V71TIs on our boat. I can go over all from my ER if needed.

 

[sixty]

Do you have the Hatteras wiring schematics?

Thanks, good Idea. The Detroit manuals don't cover alternator wiring!

 

[sixty]

Thanks Captain!

They are definitely workhorses.

I do believe they are a version of 30si. There is a big case ground and no markings on either insulated terminal. I will look closely for the spades but do not recall seeing them.

Your picture is of the original Delco 30SI. Probably the back bone of 32Vdc alternators on Detroit 2 strokes.
What a work horse.
The two large terminals are negative and positive. The case is not tied to ground / negative.
The two regulator spade/blades should be tied together just inside the square opening and read battery voltage on both when not running. When tied together, no loose wire should be on them.
If they are not tied, one post will have to be connected battery feedback.

I have the same on my 12V71TIs on our boat. I can go over all from my ER if needed.

 

[Captain Ralph]

Thanks Captain!

They are definitely workhorses.

I do believe they are a version of 30si. There is a big case ground and no markings on either insulated terminal. I will look closely for the spades but do not recall seeing them.

Look at the web pic you posted. B+ to stb, B- to port.

Male spades, side by side, inside the square hole below the B- post.
You may see just _ _ or the two connected deep _-_ in the square before the white colored regulator.

I received one 30SI with a rubber plug covering the square hole. Before you remove the plug, mark with a Sharpie pin its orientation to the case. That plug could be a jumper over those spades that make the alternator work 24 OR 32Vdc.

 

[sixty]

Thank you captain for your help! You were correct that one terminal is ground and the one positive. If you look at the delco 30si diagram it shows the small stud on the left is for reference voltage however on this alternator it is a large negative terminal. I verified this on my neighbor's boat which happened to have the same 30si alternators. Once I had the alternators wired correctly they charged great, about 37.5v. Much appreciated!