Battery Charger Blows GFCI

[idearat]

Hi folks. I have a ProMariner ProSport 6 for occasional dockside topup, plugged into a GFCI outlet onboard. Lately it pops the GFCI every time as soon as shore power is connected. Is it likely the charger is hooped? Is there any simple way to test it? It's still under warranty, but I'll probably have to mail it somewhere, and I want to be sure it's the problem before I do that.

I've tested the shorepower outlet, the cable, and the onboard outlet every way I can think of. (The gfci is simply wired directly to the shorepower receptacle; i.e. there's no real AC circuit on board, I just use the shorepower cable (carefully!) as an extension cord.) The only other 3-prong appliance I have aboard is a laptop charger, which works fine in the same outlet, though of course it doesn't draw much. I've tried a receptacle tester with a GFCI test button, and everything checks out.

Thanks for any advice!

Perry.

[GordMay]

It sounds like you may have a ground fault in your charger.
Unplug the charger.
Using an Ohmmeter, test between the U-Ground pin and the smaller flat pin on the charger cord cap (plug). Should read infinite Ohms (open circuit).

[senormechanico]

What Gord said.
Further, if the meter has a diode check feature, use that.
Reverse the leads and see if it makes any difference.
There should be NO continuity between ground and either of one the power leads.
The meter may be able to measure your skin resistance, so hold the leads so you're not touching the metal bits.

[idearat]

Thanks very much... I'll try that check next time I get to the boat... possibly tomorrow.

Cheers... Perry.

[daddle]

Actually, since an infinite resistance (no continuity) is impossible to create or measure: simply test for something greater than 24,000 ohms. Best if it is much more. A GFCI will trip at about that resistance. Dampness in the charger, especially that due to salty air, can easily cause this problem.