Alternator issues with Cummins 6BTA

[Kevin Ornellas]

Aloha,
I have issues with my alternators not providing a charge to my batteries. Just installed new one and still no charging voltage at battery terminals. Alternators are Wilson 90-01-4400.
Mahalo for your help!

Topic

[Kevin Ornellas]

Thanks guys.
My partner and I reciently bought this company and trying to fix all the band aid repairs done by previous owners. We have 79 and 86 Bertram’s.
Wiring is bad and im cleaning it up. I have no diagrams so finding what I can via your website which I love!!

Installed new alt and battery. Not getting 14 volts at battery terminals. Checked voltage at battery on other boat (same engines) and got 14 volts. Noticed ground wire on alt to starter. None on the boat I’m working on. Installed ground wire and still no 14 volts. Switched out the diodes between boats, same results.

I have a 3 wire system alt system. Only two of the wires on plug are being used.

I’ll check again all connections.

[Rob Schepis]

You say “still no charging voltage at battery terminals” but have you worked your way through anything/everything in between the battery and the alt output terminal?
Lots of questions here, not a lot of info………….

[Tony Athens]

Your Wilson part # pops up as a “wanna-be” Delco 19SI…….But what I do not know is if its a 1-wire or 3-wire unit…………..Look closely at your alternator and send me a good picture like the one attached… Chances are, you are not wired correctly………..

Also, how about a DC POWER WIRING DISTRIBUTION diagram.. You are really lacking info if you want someone to diagnose electrical systems on boat. Just by change, you do have some sharp guys trying to help, but we still need good input.

Tony

[Philip]

You didn’t post any details about your wiring, but assuming it’s wired correctly, it wouldn’t be the first time a ‘new’ alternator is bad right out of the box.

Got any pictures of the engine from all sides?

[Kevin Ornellas]

Measuring voltage with Fluke multi meter. Battery is brand new.

[Philip]

Not sure how your engine is wired, but alternators are usually pretty simple. There is usually a ground wire at the alternator, and s positive wire that goes from alternator to starter and then battery. Make sure those connections are clean, solid, and tight. Then sometimes there a sense or excitation wire that tells the alternator how much voltage to produce.

Double check all wires for clean, solid, and tight and post up how your system is wired along with some good pictures of the engine as a whole from all sides.

How are you measuring voltage? And how old are your batteries?

[Author]

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