12V71 32V Alternator Question

[pmurphy]

I'm pretty certain my port engine alternator is not working. I'd like to verify it's the alternator by testing output directly at the alternator. Can anyone tell me which leads I should be checking to get the 35 ish volts? I'm guessing the leads marked 1 and 2, then move to 1 and 4. Also not sure what the black Newmar device attached to the alternator is suppose to do and how to test that. Thanks in advance.

 

[jmooney]

Check between 1 and 2 . The Newmar device is a noise filter. I removed both on our boat. I haven’t noticed any difference. But then I use a 12 volt bank for radios . Also I think it should charge at 37 volts.

 

[Captain Ralph]

Turn your battery chargers off for a few hours with some house lights on. Not to kill the batteries, just bring them down a lil that they will take re-charging current.
Then start up the engine and measure pins 1 & 2.

You should see a nice charge.

Diode isolators may keep your 30SI alternators from self exciting. Revving up the engine may help over come this.

There is already a noise suppression cap inside the alternator.
It is also a brush-less design. Never knew one to make electrical noise.

You can try to bypass that hang-on gizmo for testing also.

 

[rsmith]

Check between 1 and 2 . The Newmar device is a noise filter. I removed both on our boat. I haven’t noticed any difference. But then I use a 12 volt bank for radios . Also I think it should charge at 37 volts.

It was for loran C interference. Not needed for current radios

 

[divert00]

You may want to put a DC clamp multimeter on the positive wire to check amperage output.
I installed inexpensive (Amazon) digital amp meters to each alternator, so I can monitor alternator output during my engine room checks.

John McCarley - USCG 100T Master
Water Colors
Wrightsville Beach NC

 

[zigzag930]

FYI,

If no output, you can still find the internal voltage regulator boards online. My 32v alternator wasn't working. I popped a new VR board in there ($30) and it has worked perfectly ever since.

J