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 Post subject: W50 alternator high voltage
PostPosted: 01 Jun 2019 09:51 
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Tactictian

Joined: 25 Apr 2016 10:25
Posts: 110
The voltage on my batteries while running the engine is 15.5V which seems high to me as I believe it should be 14.4V.

How do I test the voltage regulator on the alternator? I believe it is external and by the secondary fuel filter. There is also a large capacitor next to the alternator that I'm not sure what it is for.

Is it possible to just replace the regulator if that is what is bad or do I need to replace the entire alternator? Should I get one with an internal regulator?

Any tips on how to debug this high voltage?


 
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 Post subject: Re: W50 alternator high voltage
PostPosted: 02 Jun 2019 19:01 
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Midshipman

Joined: 15 Jan 2010 16:13
Posts: 54
Where are you getting the high reading? First thing I would do would be to put a volt meter on the batteries to make sure of the reading. If indeed it is 15.5, then my guess is that it is the voltage regulator. Depending on your system, if you have an external one, it is easily replaced. Just take it in to an auto parts store and you should be able to find an equivalent replacement. What alternator do you have?


 
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 Post subject: Re: W50 alternator high voltage
PostPosted: 03 Jun 2019 16:25 
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Skipper

Joined: 29 Dec 2006 09:38
Posts: 556
I will second the questions—-where are you measuring the voltage? Are you sure your voltmeter is reading right? Right off he back of the alternator and before an external regulator, it could be that high. If you have an external regulator, you are correct it should likely be lower 14.8 or so if it is in bulk stage. Less when the unit has been run for 20 minutes. External regulators are often programmed to run for 8-20 minutes and full tilt before they start sensing and reducing voltage to float levels: 13.6 or so. The external units vary in their programing but are largely have similar sequences and voltage ranges.
if it is an external smart regulator, I do not think you will find one at the autoparts store (I could be wrong about that). You probably need to go on line to get one for marine application.
Ray Durkee


 
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 Post subject: Re: W50 alternator high voltage
PostPosted: 04 Jun 2019 16:38 
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Tactictian

Joined: 25 Apr 2016 10:25
Posts: 110
The voltage measurement was taken at the batteries with my meter. I'm confident it is correct as I have a fluke meter and also a separate battery mornitor and they both agreed on the reading. I checked the connections and the regulator terminal on the back of the alternator along with one of the grounds were slight loose. I tightened those terminals and now I am reading about 13.8V when charging which seems on thelow side. so I think the high voltage problem was caused by the regulator sense wire not making good contact so the alternator was running at full tilt. I need to take a voltage drop measurement from the output of the alternator to the positive battery terminal while charging. I suspect the cabling is undersized and since it goes to the ammeter in the cockpit first then to the starter it it likely has some significant drop in it.


 
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 Post subject: Re: W50 alternator high voltage
PostPosted: 04 Jun 2019 22:30 
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Skipper

Joined: 14 Jul 2012 20:36
Posts: 396
I was thinking the sense wire. Its the blue wire in my set up with an external Balmar and is the first place I would look. A low voltage reading will call for more field voltage. All my charging and starting wiring is greatly oversized. I think you're on the right track. Did you say what type of regulator you have. The 13.8 is a float voltage. Are your batteries sitting on the house changer, fully charge, is it secured? With an internal regulator they always start with a voltage higher than 14.5.

_________________
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 Post subject: Re: W50 alternator high voltage
PostPosted: 06 Jun 2019 16:42 
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Skipper

Joined: 29 Dec 2006 09:38
Posts: 556
Honestly, it seems that you have found the problem and everything is fine.
Ray Durkee


 
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 Post subject: Re: W50 alternator high voltage
PostPosted: 06 Dec 2019 02:54 
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Tactictian

Joined: 25 Apr 2016 10:25
Posts: 110
Well I continued to have problems with my alternator charging at low voltages over the last few months. I finally bought a replacement regulator and ran a new cable from the alternator to the starter. I was thinking about running it directly to the battery switch, but this is basically the same thing and the cable run is a very similar length. Plus I coulnd't find the appropriate lug size for the battery switch where I'm located now, and was able to get the starter lug size.

I believe I also found the original source of the problem when I was adding the thicker wire (1/0 gauge). The old charging circuit came off the alternator then went through a wiring harness before it goes to the ammeter in the cockpit. I separated the wiring harness and there was significant corrosion inside and the connection for the main power line off the alternator was broken. So I was getting poor contact and high resistance. I don't believe the setup was ideal to begin with due to the long thin cable run.

There is almost no voltage drop now between the battery bank and the alternator. I cleaned up the rest of the wires in the wiring harness with corrosion and things seem to be running well. The new regulator I purchased is just a replacement for the original on the boat (automotive style, but adjustable voltage level). It is currently set at 14.45V. Do you think I should change the output voltage to something different? I have golf cart flooded batteries in the boat.


 
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