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 Post subject: Alternator, voltage regulator working but no charging....hmm
PostPosted: 12 Dec 2009 15:59 
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Able Bodied Seaman

Joined: 23 Dec 2007 23:08
Posts: 42
When I purchased my boat (#198, VANORA) the alternator was not working and no alarms sound on start-up (or any other time). The previous owner had disconnected the tachometer when replacing the alternator and couldn't remember where it was attached. Now, the tachometer works as do the water temp. and oil pressure meters. The meter showing amps "works" but shows zero when the motor is running.

I have taken the alternator and voltage regulator to two shops and both say they are working to spec. An electrician came aboard and was perplexed by the system (particularly as there was no ignition switch). We determined that there was no current to set up the field (when we jumped a wire directly to the field post on the alternator it caused the alternator to run "full-tilt" and the amps gauge jumped up to fifty amps). I believe he also checked the fuel switch and determined that we had a charge there at the output side. So, although my solar panels keep everything charged, I would really like to have the alternator working. Any tests for the fuel pressure switch that I can conduct that you folks know of? Any other suggestions. Oh, I have also checked and cleaned some of the ground connections to no avail. Lastly, on my ground post there are a series (three?) wires attached, all of whom are quite thin in gauge. Is this system grounded via the mounting or does the circuit run through those small gauge wires. The alternator is a Motorola with an external regulator.

Thoughts or suggestions anyone?


 
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 Post subject: Re: Alternator, voltage regulator working but no charging...
PostPosted: 13 Dec 2009 08:51 
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Skipper

Joined: 21 Oct 2006 15:36
Posts: 268
Falco-

I just checked the electrical schematic for the boat as originally designed. There original voltage regulator was supplied power from the downstream side of the fuel pressure switch. You can test this switch with an ohm-meter. With the engine off (i.e., no pressure in the fuel system), you should get infinite resistence (an open). With the engine running (i.e., fuel lift pmp operating) the pressure switch will close and you should be able to measure negligible resistence. Also, with the original wiring, the gage panel lights should go on, and the water temp. gage, oil gage, and the water temp and low oil pressure alarms should have power with the engine running.

In addition, the voltage regulator should have 3 wires going from it to the alternator. The red wire should go to the reg. connection, the green wire should go to the field connection, and the black wire should go to the ground connection.

I would first check to see if power is getting to the field connection (green wire). You can do this with a volt meter. If you get no voltage reading at the alternator with the engine running, then your problem is likely with that conductor. The first thing I would check would be to see if this field circuit was/is wired through the battery on/off switch. The better on/off switches have a small switch within it that can be wired to the field circuit, which denergizes the field if the battery switch is turned to the off position. This prevents damage to the alternator if the on/off switch is inadvertantly switched to 'off' when the engine is running. On my boat, this switch wasn't wired in but it is now!!!

If you're sure the voltage regulator and the alternator works, and you are getting power to the field, you have a real dilemma. If you have the original single stage voltage regulator, I would replace it with a 3 stage regulator. I have a Balmer 3 stage regulator, and it's been great. The single stage regulators don't properly charge your batteries, and I would recommend the change regardless. If that doesn't fix the problem, then the only thing left is the alternator.

Jim
Odyssey #191

_________________
Jim Voelxen
Odyssey #191
Home Port: Osterville, MA


 
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 Post subject: Re: Alternator, voltage regulator working but no charging...
PostPosted: 09 Jan 2010 22:36 
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Skipper

Joined: 16 May 2009 08:06
Posts: 236
When this happened to us, the problem turned out to be a failed connection inside the molded gang plug for the main wiring harness. I believe it was the wire that carried the alternator current from the alternator to the amp meter on the panel. I cut the wire and jumped it accross the molded plug and have not had the problem since. That was 7 years ago.


 
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