Found out why my alternator wasn't putting out current ...

[Scott T-Bird]

Disconnected the ring from the stud and the cable just slid out without any resistance. Underneath that heat shrink, it seems that there is barely even a crimp. Cable strands were very clean as well ... no apparent corrosion.

Question ... if there were no amps passing thru that cable, will the alternator be ok or will diodes be ruined?

I started mounting a new external regulator but haven't made any connections yet.

 

[DArcy]

A flakey connection might cause the diodes to fail. If There was current flowing and then the cable separated it could cause a voltage spike that would fry the diodes. But if the cable was only hanging on by a thread there probably couldn't be enough current to cause the voltage spike. You pretty much have to check the diode pack to know if there are any damaged diodes. Or measure the alternator output under a bit of load and check for AC ripple.
I've been re-wiring lately and your discovery is why I pull test the connections after crimping just to make sure.

 

[RoyS]

Alternator diodes can be tricky. For years, while my alternator could charge my batteries, I had horrible static on my hand held VHF radio. Alternator eventually failed and I replaced it and discovered no more static on the radio.

 

[Daveinet]

It really depends on the alternator. If it is internally regulated, it will probably survive. If it is externally regulated, you may end up with an issue. If I was betting money, I would bet the diodes are OK. Semiconductors fail exclusively because of heat. Either the heat is generated quickly and they go bang right away, or they or they fatigue and fail over time. In the case of no load and no regulation, the voltage will rise till the diode conducts backwards (PIV). If there is enough current, the diode will fail. One thing to remember, the diode capability will likely match the coil capability. So as the current in the diode goes up, the ability of the alternator to put out more current diminishes. Coils usually survive overheating better than semiconductors, but the voltage will still sag - hopefully enough to prevent the diodes from failing.

ON EDIT: There is another senario. When you break the load connection on a coil, the voltage spikes. (This is the way your spark coil works) If you get multiple breaking and making of the load connection, the successive spikes could take out the diodes.

 

[Scott T-Bird]

Thanks for the replies! This is all a bit of a mystery to me. I had no reason to question the alternator or the external MC 614 regulator when I purchased the boat last year. Over the winter, I disconnected and removed both the alternator and the regulator to work on the engine. I removed the alternator cable at a fuse near the battery before disconnecting the alternator end. The battery end is where the cable was later found to be loose last Sunday. I was changing out parts to put a new fused bus in place and I found the loose connection when I pulled it off this time. I didn't notice the loose connection when I put it together last spring (but I probably disrupted its tenuous condition at that time).

So, aside from the alternator cable, I am almost positive I connected all the regulator wiring as I originally found it. I had a picture and the connectors make it fairly simple. The only questionable item that I found when I put it together in the spring was the brown ignition input that has a male spade connector at the end that is supposed to connect to the ignition. It was originally secured to a pair of wires attached to a connector that came out of a loom that went to the starter. The wires that came from the loom were attached to a plastic connector that had 2 female spade attachments. I'm not sure which of the 2 it should have been connected with or if it mattered. The instructions say that if the connection comes from the loom, it could be either an ignition switch or an oil sensor switch. Based on the color of the 2 wires, I think I can determine which switch is which when I connect my new regulator.

 

[MitchM]

you are one lucky man to have found that bad crimp the way you did ! congrats...

 

[garymalmgren]

1. Strip back wire.
2. Solder stripped end. ( Or tin the wire, if you prefer that word)
3. Apply flux on inside of connector.
4. Insert wire and crimp.
5. Heat up crimped joint so solder on stripped wires adheres to connector.
6. Cover with heat shrink if applicable.

This way you have a joint the is crimped and soldered.
It won't let go!!

gary

 

[Scott T-Bird]

Finished the installation on Saturday and all is well! After reading the regulator instructions, I'll go back and tinker with the programming.