Alternator has gone unserviceable

We are cruising from Pender Harbour to Desolation Sound. About 2 hours into our journey, the gauges (Tach, oil and temperature) shut down. The amps in/out on the bank had gone negative, indicating no output from the alternator (Amptech125). The Voltage regulator is a Balmar MC612. With a clamp meter, I have verified there is no output from the alternator. The clamp meter confirms output to and from the house bank. I have selected the Blueseas ACR between the House and Start banks to off. The Magnum charger panel provides amps in/out to the house bank and voltages.

Current situation: solar panels are approximately maintaining the house loads and the house bank is at 91% SOC. I have a northern lights 5 kw genny.

I have a mechanical oil gauge on the engine indicating normal pressure. Digital laser thermometer indicates normal temperature. Digital tachometer indicates cruising RPM.

I suspect the Amptech alternator is the problem. I have a new identical unit, which I intend to install in place once I’m at anchor. However, what is the likelihood that the MC 612 is the issue and how would I diagnose that situation?

Any other advice/recommendations most appreciated.

Jim

The balmar 612 pdf has a troubleshooting section. Have you checked that?

check the field voltage using the engine ground. If the tach is driven off the alternator I would suspect the alternator. The only caveat is the other gauges not working which sounds like ground issue

Gauges and alternator down sure sounds like a bad connection somewhere.

David

Well! How do I describe “50 shades of Red?” I’ve been working with a TF member offline. After many tests and checks, he deduced it was an ignition problem. Key was as on…but the breaker was off. I’m pretty certain it was accidental when I flipped a switch to check the analogue voltage gauges.

Jim

I wish I could say something like that has never happened to me, but alas....

I'm sure I have done that some or other. I can't remember when but I'm sure I must have, but my memory is failing

That has never happened to me…wait it did last week and I have been around boats my whole life and have been a certified marine electrician for 22 years.

If you look at the Tecma Solenoid thread you will see I would never do that!

Rob

The Blue Sea Toggle Guards are a wonderful thing for those of us with fat fingers, poor eye sight, dyslexia, etc. I have at least a dozen of them on my boat, and you know why.....

Thanks TT. I shall get some on my return!

Jim

Damm gremlins

JDCAVE said:

After many tests and checks, he deduced it was an ignition problem

Click to expand...

But the troubleshooting was spot on!!! I am quite certain everyone learned something going through this exercise! lol.

When I was in the Marines I took over a troubleshooting problem on a Helicopter APU that would not start. I did some beautiful troubleshooting that pinned it down to a fuel issue in the fuel tank area. Yes...the tank was EMPTY. Spent 2 days doing that...never once bother to check fuel level.

Part of my problem was/is, I have never explored the vagaries of the MC612. It is way down low and partially obscured by the battery box. It requires weird tools to change settings. It worked so I had never paid any attention to it until yesterday. A simple check of the lights on it (again, difficult to see), would have revealed it wasn’t getting power. I guess the brown wire supplied power to the MC612 from the ignition switch. Once we determined it was a power issue, we checked the ignition. The key was turned on, but the breaker was not.

Jim