Reverse Polarity Problem

[dabfd]

I purchased Dr. John's Tomcat recently. We trailered it to the west coast from OK last week with no problems. Have been going through the boat in the driveway and am finding most of the systems working.

However when I supplied the boat with shore power from the Honda 2000 everything worked great until the Guest 2621 charger is turned on. At that point the reverse polarity light comes on and the battery charger will not work. When I turn the charger off the reverse polarity light goes off. I own 2 Honda 2000 generators and tried both with the same result. I also checked the wiring at the panel and the charger, they appear to be correct.

Having owned a prior boat I know about ignoring the reverse polarity light when using the Honda and everything works great. Our previous boat was equipped with a much larger inverter/charger. However the Guest Battery Charger has reverse polarity circuit protection. Does this protection keep the charger from working when reverse polarity is detected? If so what is the option with out installing a new charger.

Dave

[matt_unique]

Welcome to the litter as they say!

I would not ignore the reverse polarity indicator. It means there is a short of some kind and you narrowed it down to the charger.

Verify with Dr. John that he used it before and it worked OK. (Mine was wired wrong when it was brand new and had to be fixed). If yes, I would start examining every wire.

I only once had a reverse polarity issue and it was due to a short in the wire connecting the reverse polarity switch to the main bus board. (See my album under installation and fixes). It was not readily evident until I got right in there to do a close inspection with a flashlight.

Good luck - you have a fine vessel!

[Larry H]

If the reverse polarity light only comes on when running the Honda gen, then the generator is the problem.

It does not mean that anything is wrong with the Honda. The Honda generators do not have a real 'ground'.

My trawler does the same thing, the RP light comes on (flickers) when I run the Honda 2000 generator.

My battery charger operates normally with the generator, and the light never comes on when plugged in at the dock.

You may have to replace the charger with one that does not have a reverse polarity sensor.

[Sea Wolf]

The Honda generators do not have a ground, just two wires carrying a 60 cycle ac (alternating current) 120 volt current that is developed by an inverter powered by the 12-volt alternator coupled to the Honda gas motor.

They call it a "floating ground", but it's really no ground at all.

I imagine your charger is sensing that there is no connection between one of the "hot wires" supplying the current, and the ground wire, which is the normal situation when connected to any shore power/normal household outlet.

First thing I'd do is try shore power and see if you get the Reverse Polarity light. If not, the "floating ground" is probably the problem.

I would also call the Technical Representatives at 1) the charger manufacturer and 2) at Honda, as they probably get this problem presented to them routinely. They should be able to tell you if you have a real malfunction, or just a problem that can be fixed, and how to go about it.

(I also get the "flickering Reverse Polarity" light on my Sea Ray when using the Honda 1000i generator, but the charger does go ahead and charges the batteries.)

Good Luck!

Joe.

[jkidd]

The 2000 does have a ground screw on the front of it. Try grounding the Invertor and see what that does to the light. With a multimeter you should see roughly a 120 volts across 2 flat blades or the Hot and Neutral. From the Hot to the ground you should see 120 volts and from the ground to the neutral there should be 0 volts. Without the ground you might read some voltage there. That is what would cause the reverse polarity light to come on or flicker.

Without the ground you have the possibility of touching something like a toaster or toaster oven and getting a shock. It's a safety thing.

On edit:
This is out of their manual.

GROUND SYSTEM
Honda portable generators have a system ground that connects
generator frame components to the ground terminals in the AC output
receptacles. The system ground is not connected to the AC neutral
wire. If the generator is tested by a receptacle tester, it will not show
the same ground circuit condition as for a home receptacle.

So taking the above measurements might not show the readings that you normally see. But the ground wire should get rid of the problem. Now you just need a really long wire to carry around with you.

[Captains Cat]

[hardee]

Boat US magazine had a fairly extensive write up on this in there Q&A technical section, I think the last or next to last issue, (a green cover, closeup of the bow of a green boat with a peek of a sampson post.) Seems like it was the same kind of idea that it is made to sense a real ground and with the generators there isn't one. Advised to contact Honda and the battery charger company, if I remember right.

Harvey
SleepyC

[thataway]

I am going to say about the same thing that Joe said. The Honda I series are Inverter Alternators--not generators. Thus do not have a ground. The 120 volts floats off the inverter (same as using an inverter off the battery might cause the reverse polarity to come on--if it was in the circuit). The reverse polerity is "normal". I don't believe that gounding the frame of the generator to the boats bonding sysem ground, or the ground of the AC input will get rid of this problem.

I have installed a second battery charger, which is not affected by the reverse polarity, and is far more powerful than the factory Guest battery charger, which I just use to maintain batteries at the dock.

[dabfd]

PROBLEM SOLVED-Hey thanks for all the input. It was all very helpful.

After talking to the Guest Battery tech and emailing previous owner it caused me to double check the wiring of the charger.

Turns out the marina were the boat was kept had recently installed a new charger and had switched the ground and the neutral wires. Now everything works great and NO reversed polarity light when the Honda 2000i is supplying the power.

Time to get on the water, their calling for 80 degrees on Thurs.

Dave

[Doryman]

I posted a message in another thread that readers of this thread may find interesting.

Warren