No Alt output leads to melted wiring harness

[Bobg]

A while ago, my alternator wasn't putting out, however the tach still worked, so I tightened the belt, cleaned all the electrical ends, that didn't work so I took the alt in, it tested bad, bought a new one from Blue Circle, it wouldn't put out either, started following the wires, that's where I found the problem.

I erroneously assumed, (should have read the archives better) that if I had a voltmeter, the harness upgrade had been done. It wasn't.  In fact the plug behind the instrument panel was horribly melted and corroded, (luckily no fire) resulting in no continuity in the Alternator wire.

The gist of this post is not the Alternator problem, but to remind other owners, that no matter how many neat upgrades are done, how much electrical has been added, or how nice everything is, PLEASE SEE IF THE HARNESS HAS BEEN UPGRADED.

Stu and Ron and others have been warning us of this problem many times, but due to the fact I had a voltmeter, I didn't pay attention as close as I should have, I now know that in 88 we had voltmeters but still had the old harness. (in fact if someone were to ask me it the upgrade had been done, I would have said yes)

I am going to cut that plug out of there and either use a terminal strip, or hard wire the ends to the instrument panel.  Then check the engine end.  according to the archives,  I should be able to run the  output wire from the Alternator to the batteries instead of up to the switch as before. "right"?

The PO was a member of this site, many upgrades had been done, dedicated starter battery, combiner, propane locker, 4 T105's, glow plug solenoid upgrade, ect, and was very particular in what he did on the boat, all these neat things  except the most important, the harness upgrade.  So please  check it out as I should have. (It is so easy to take a peek)

As Stu and Ron say, this is one upgrade that can save your life

[Stu Jackson]

...I should be able to run the  output wire from the Alternator to the batteries instead of up to the switch as before. "right"?

Conceptually, yes.

As you've learned, the devil's in the details.

Run the alternator output to the house bank, not just "the batteries."

Then check the wiring from your 1-2-B switch to the engine compartment.  The C post, which used to go to your alternator output, and then with a small wire from the AO to the starter solenoid, should be changed to run directly from the C post to the starter solenoid, eliminate the small wire between the AO and ss.  Reply #11, here: http://c34.org/bbs/index.php/topic,4949.0.html

You will need to LEAVE the wire from the 1-2-B switch to the engine compartment and run a NEW wire from the AO to your house bank.

Draw it out on paper first.

Thanks for the report, Bob.  All the best.

PS --- And with a voltmeter in the cockpit panel, what was alternator output power still doing up at the panel?!?

[Bobg]

Thanks Stu, I'll go up to the boat and do the upgrade, The Pos output wire went from the Alternator output to a black junction box on the engine, then the orange wire went from that junction box to the ignition switch on the instrument panel.  I don't know why they didn't just run the wire to the switch, I mean whats up with the junction connection.  all it was was two tabs set in some kind of rubber with continuity.
  Anyway I'll have to really see what I have, I do know I have a combiner in the mix, and a on off switch that activates the starting reserve battery, (one of those switches with the red removable handle)

I will eliminate that long run from the Alternator and connect it to the house bank, somewhere, or just to the starter solenoid as some others have done.  And do some testing to make sure all the banks are getting charged.

Interestingly, when I brought my Alternator in the guy had a big sign on his wall saying that Alternators are not Chargers, they are battery maintainers.  He encouraged me to run my Honda 1000 for awhile after a few days at anchor before starting the engine, to charge the batteries through the onboard 3 stage charger I have, to reduce the load the Alternator has to put out to charge batteries that are way down.
Thanks for your help Stu
Bob

[Stu Jackson]

Interestingly, when I brought my Alternator in the guy had a big sign on his wall saying that Alternators are not Chargers, they are battery maintainers.  He encouraged me to run my Honda 1000 for awhile after a few days at anchor before starting the engine, to charge the batteries through the onboard 3 stage charger I have, to reduce the load the Alternator has to put out to charge batteries that are way down.

That's pretty much true, 'cuz running the engine for the time it would take to get the alternator to fully charge the house bank would take forever.  See the Battery Acceptance topic, here:  http://c34.org/bbs/index.php/topic,4787.0.html  

It's not so much the load on the alternator, in that he's only partially correct, but it is the time it would take as the charging tapers off because of battery acceptance.

For alternator load upon startup with a depleted (overnight on the hook) house bank, see Small Engine Mode, here: http://c34.org/bbs/index.php/topic,4669.0.html  That wouldn't work without an external regulator.

[Ron Hill]

Guys : Any C34 thru the 1992 production year could have the original "screwed up" wiring harness.  If you have an ammeter instead of a volt meter and a big wad of black electrical tape covering the 8 pin trailer connector - that's a dead giveaway, but it's not the only item to check.

Look and see if there is a single short wire about a #10 gage going from the alternator output to the starter solenoid (distance of about 6 inches).  If that wire is not there and the alternator output wire disappears in to a wire bundle, you don't have the wiring harness upgrade - it's that simple !!!