Split voltage from portable generator resulting in reverse polority onboard

[BeaverAggie]

Howdy,

I am just looking for a couple of answers or some troubleshooting hints for my parents as they are cruising in Panama and still two weeks from civilization.

My dad purchased a Honda EU2000i about 7 months ago to help in charging the batteries of his catalina 42 during their resting periods in bays, unfortunately he lost the receipt. The main problem he has encountered is that there is equal distribution of voltage between the hot(positive red/black) side and the common white wire. Here is the e mail he sent me. Any suggestions would be greatly appreciated and I know they will try and contact a honda dealer in Panama City but they are still 2 wks away from there.

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Thanks for checking into the generator for me. Here's what I can tell you. I was running the generator charging the batteries through my inverter which has a built in charger. I went down below and my reverse polarity light was flashing. Normally reverse polarity means that the voltage is coming in on the white common wire and not the black or red hot wire. I didn't believe it was the generator at first, but after checking all the outlets and the cord from the generator to the boat, I discovered that the problem was the generator it self. Normally when you check the voltage you check at the plug with the volt meter first you check for 120 on the hot side by touching the ground plug to the hot side. You should have 120 volts give or take. when I checked it it was 62 volts on the hot side. I then checked the common side which should have no voltage and it also had 62 volt. combined you get the 124 needed, but because half of it is coming from the common side the boat reads it as reverse polarity. I took the generator apart as much as I dared and found no burnt or obvious shorted wires. As far as I could tell nothing had come unplugged everything looked normal. Everyone I have talked to says its impossible to have split voltage like that. If it was a short between two wires both wires would have 120 not split evenly with 62 on each side. The 12 volt side of the generator doesn't seem to be affected, but I will verify that tomorrow. The funny part is the charger in the inverter is putting out 93amps of perfect power. I am just afraid that running it with voltage on the neutral may ruin my inverter which costs about $2000, so I don't want to screw with it. It just doesn't make since. It is a Honda EU2000i, it is only 7 months old it would be under warranty but I don't have the receipt and I am out of country.

Thank you again for taking the time to look and offer some assistance!

 

[Silvertip]

Re: Split voltage from portable generator resulting in reverse polority onboard

When checking voltage at the generator the meter is connected across the hot (the narrow slot in the receptacle) and neutral (the wide slot in the receptacle). That should measure 117v give or take. The next check is to measure from the hot slot to the ground slot. That too should measure 117v give or take. If you measure from the neutral to the ground slot you should read zero since these two lines are essentially parallel. If you do measure a voltage (any value) there is indeed a generator problem. A single phase unit showing a reading of 62 volts says one half of the 60 Hz sine wave may be missing which may account for light flashing. But don't overlook the fact that the power cord between the generator and the inverter may be the culprit, especially if someone has replaced a plug or receptacle on it and inadvertently swapped the hot and neutral or ground leads. However if that has worked in a similar application before it should work now. Other than that I don't see how you can end up with a split voltage from a single phase system or why you measure voltage from neutral to ground except due to an issue with the generator.