reverse polarity light

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Jul 3, 2006
13
Hunter 336 Noank
I have a Hunter 1996, Hunter 336. The boat is wintering in the water this year in Conn.I was down there today to charge the batteries. I plugged the boat in at the dock like I always do and turned the battery selector to ALL. Turned on the AC side of the panel on and turned on the outlets and the charger for the batteries and noticed the reverse polarity came on. It only come on when the charger is switched on. I have owned the boat for 5 years and have not made any changes to the electrical system. Any thoughts?
 
Dec 2, 2003
1,637
Hunter 376 Warsash, England --
I suggest you may have no neutral connection to the boat, or there is a disconnection of the neutral wire in your shore power lead or even within the boat.
Also, there should be a GFCI, GFI or RCD in the line and it should trip and the charger should not come on.
If it does come on then there would appear NOT to be one of these essential safety devices in line.
If you do not understand the real situation I suggest you get a competent person to look at it.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
I'd second Donalex. the polarity light only comes on when the neutral has power supplied to it. not very likly that the shore power circuit changed on the dock side and since you did not change anything on the boat the only thing left is the shore power cord and plugs. Try wiggleing the plug in the outlet while watching the polarity light.

You can also check with a multimeter
WM has the plug wiring diagrams so you can determine which terminal is hot, neutral, and ground for your specific plug. On the boat side you should get a circuit (voltage) between hot and neutral and hot and ground and no circuit between neutral and ground.
the other possibility is the battery charger is bad. I probably just need s stern talking to or slap in the back of the head. that will teach that charger to be bad.
 
Jul 3, 2006
13
Hunter 336 Noank
Bill, when i plug the boat in and turn on the ac side the light does not come on. So it would seem that it is not the dock. It only comes on when the charger is turned on. Your best guess is the charger?
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Marine bat chargers

Marine battery chargers use an AC transformer to step down the voltage from 120 to 12 volts AC then rectify it to DC. The step down transformer has the hot and neutral leads on the on the high voltage side isolated from the hot and neutral on the low voltage side. If a connection is made between the two the unit could still function correctly (auto bat chargers have just this arrangement) but you would be risking some galvanic corrosion related problems. Turn the unit off and test for a connection between the neutral on the high voltage side and the case ground of the charger. There should be no connection.
The great Roosack predicts that you will find that there is a corroded neutral wire connection either going into the unit or inside on the circuit board which is restricting current flow back along the neutral and dumping it into the ground circuit.
 
Dec 2, 2003
1,637
Hunter 376 Warsash, England --
sole pleasure

Hi,
I have made a diagram explaining my reasoning for the Neutral wire being open circuit.
Sadly this site re-compresses it so it is no longer legible so I have had to delete it.
Then I made it into a .pdf but that facility is not available here either.

Anybody wishing to see this explanation please Private Mail me and I will forward the diagram.
i.e. Go 'Forums' >'Private Messages'. Then 'Donalex'.

Regards,
 
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