refrigerator will not run on DC with the engin running-gctid383898

[Guest]

I have a 1986 Bayliner motor yacht 38'. My refrigerator is a Norcol , it will run on the battery when at anchor. The minute you start the engine it will pop the breaker. So when on a trip I have to run the Jenny. I hope i am doing this right, my first time with a question.?? Thanks coach2254

[seaclusion]

Perhaps you should check the output voltage on your engine alternator .......voltage regulator may be to high or bad grounding OR D C CONNECTION AT REAR OF FRIDGE ......

[mmichellich]

Best guess, problem with boat/engine side and not refer. Likely either excessive low or high voltage.

[dmcb]

This is sure a head scratcher.

If there is a voltage spike you should also see it on the lights. They will get brighter.

Low voltage would mean the batteries were down but if the fridge is working before the engine starts, that wouldn't seem to be the problem.

As said I don't think its the fridge.

A loose wire shouldn't pop the breaker but it might if it creates heat. Vibration of the engine might trigger it.

Is any other high draw items also affected? Blowers for example.

I would measure the voltage of the alternator output. For discussion it should be below 15 volts.

If the batteries are wired normally one engine charges the house bank and the other the starting bank. Which is which escapes me at the moment.

If voltage proves OK, I would combine your battery switch so both engines charge both banks. Then try one engine, then the other to see if the alternator or one engine wiring is the cause.

If it does it on one but not the other you know where the problem is at least.

If it still does it on both, I would switch breakers in your panel and see if it is the breaker itself.

I think by this time you will have somewhat isolated it. Finding what it isn't is almost as good as what it is.

Sooner or later you hit the problem.

Another test would be at dock with your batteries down a bit so your charger is working, turn off the 110 volt switch at the breaker. That will force the fridge to 12 volt mode.

It should be about the same as a normal alternator as the voltage will be elevated to charge the batteries, just like the engine running.

If it does pop the breaker, I would lean towards a bad breaker.

Just a layman's approach to finding the problem. We have some good electricians here who may have a better idea.

Doug