Merc 470 alternator install - but sparks from the cable. Did I goof?

[boltonranger]

Probably not as dramatic as it sounds.
Wagner dc-60 kit with one wire alternator.

I wired as Bondo-o suggested (Thanks for the help Bond-o!)and used the Delco diagram.
removed the orange wire; and the alternator wire to the solenoid on the starter.
Cleaned the connections etc. All seems good.

Got rained out before I could put it on the muffs in the driveway;
But noticed a small spark when I put the battery back in the boat.
I have 2 large cables on the red post and 2 on the black post.
That's for the trim pump and the rest of the boat.

Both black cables disconnected will show 12.71 volts when bridged through my voltmeter to the neg. battery post.
Key not in the ignition. Lights and blower off, no radio or clock.
I've read some of the "sparking cable" threads and it's kind of a mixed bag.

Never had an alternator in the boat 'til now - just upgraded from the original setup.
Someone said a voltage regulator will spark the cable to set it self or something.

My only other thought was I left the red/purple wire on the original voltage regulator, the instructions said it was kosher to "abandon it in place on the regulator" Before rewiring my VR was putting out 17.2 volts - - could the regulator be causing a parasitic load?

I'm a little stumped.
Should I have done something different?
-br

 

[stonyloam]

Re: Merc 470 alternator install - but sparks from the cable. Did I goof?

Remove all of the wires from the old voltage regulator. Fold back and tape up the wires from the stator. BTW don't know how you did it, but for safety ALWAYS connect the positive cable before connecting the negative, and always disconnect the negative cable before removing the positive.

 

[boltonranger]

Re: Merc 470 alternator install - but sparks from the cable. Did I goof?

You think the old VR is drawing current Terry?
-br

 

[stonyloam]

Re: Merc 470 alternator install - but sparks from the cable. Did I goof?

You think the old VR is drawing current Terry?
-br

Any wire with purple on it is usually hot, so if the regulator is defective it very well could be. Best to remove everything.

 

[boltonranger]

Re: Merc 470 alternator install - but sparks from the cable. Did I goof?

Good to know.
Ok I'll remove red/purple in the morning and try again.
Also yes I did happen to put black cable on last.
Appreciate the reminder.
Thanks for the help Terry!

-br

 

[1977 SILVERLINE]

Re: Merc 470 alternator install - but sparks from the cable. Did I goof?

Is the wire connected to the alternator switched power or constant power?

 

[generator12]

Re: Merc 470 alternator install - but sparks from the cable. Did I goof?

"
...Both black cables disconnected will show 12.71 volts when bridged through my voltmeter to the neg. battery post..."

Hey guys, hold on. He's finding source voltage with a multimeter when he opens the circuit and measures across the open.

I don't know what type of meter he's using (analog, digital, 10,000 ohms/volt, etc.) but I can virtually guarantee the same results on any of our boats. Any circuit that can leak enough current to move the meter up the scale will do this - and that can be forty or fifty microamps.

Ranger, switch your multimeter to amps and put it into the circuit the same way - in series with one of the battery leads - with everything turned off. Then keep switching it into more sensitive ranges until you hit one that gives you a reading somewhere around mid-scale. If it's a few milliamps or less, don't worry about it. You can leak that much across wet or greasy terminal strip connections. It doesn't indicate a wiring problem. Now if you see 100 milliamps or something like that, start looking for something to disconnect to make it stop.

 

[boltonranger]

Re: Merc 470 alternator install - but sparks from the cable. Did I goof?

Well thank you for the reply Gen12.
I measure .3 amps with my clamp-on digital meter at the positive battery cable.
This is while everything is OFF.
Is this negligible?
Not sure what to make of it.
-br

 

[generator12]

Re: Merc 470 alternator install - but sparks from the cable. Did I goof?

Ranger, if your reading is accurate, it's too much leakage. That would be almost one/third of an amp, or about the same as a 4 watt bulb. (I assume your meter is capable of reading DC current, right?) If I were doing it I would double-check by opening the circuit and inserting an ammeter in-line. The magnetic-reading types in my experience are a little "iffy" and can vary depending on the positioning of the jaws when measuring. Okay for higher current stuff, but touchy in this range.

If you find it is in the area of .3 amps, I guess you'll need to begin opening circuits one by one until you see an impact on the current draw.

Harness wiring on any machine that vibrates is vulnerable to friction stress, and in a boat there is also typically moisture exposure. I've seen many examples over the years of wiring grounding out, short circuits, and cross-talk in similar situations (industrial machinery). Almost every time, it was a single spot in the assembly doing it and, when corrected, everything would work properly.

The process of finding it is specific to the design of the assembly. In boat wiring, it's usually a matter of taking each possibility one at a time and eliminating it.

Best of luck.