Correct polarity with generator

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oddbod
Posts: 37
Joined: Mon Oct 10, 2016 7:56 am

Correct polarity with generator

Post by oddbod » Sun Jul 08, 2018 10:45 pm

Hi Forum, hoping someone can help with a technical issue.

Just returned from a lovely long weekend away on the boat. I took my Honda 1kw generator and plugged it into the shore power socket yesterday to run the Outwell coolbox and top up the batteries. All ran well. Disconnected it overnight.

This morning went to run just the Outwell from the generator but couldn't get the coolbox to run from the 240 plug. Looking on the AC control panel, the red POWER light was on but only one of the polarity lights. (Two red lights should illuminate when correct polarity is met) Tried a friends generator but the same issues.

Got back to the marina this evening and plugged the same cable into the marina shore power and had full 240 shore power supply!

Any suggestions?

Thanks in advance.

DACS
Posts: 38
Joined: Sat Jul 19, 2014 10:59 am

Re: Correct polarity with generator

Post by DACS » Fri Jul 13, 2018 12:12 pm

Earthing on portable generators is always problematic and means that the lights on the control panel will probably indicate a fault.

Electronics can be damaged by the output from a generator, especially if the output is not a pure sine wave or is badly regulated. What sort of generator are you using? Cool boxes are pretty simple electronically. Yours probably has a built in power supply to provide 12v from the mains input and this may have been damaged. If so, your simplest remedy may be to use an external power adapter to supply 12v to the cool box.

Since your cool box can probably run on 12v, it may be safer to run the cool box from the battery and use the generator to keep the battery fully charged.

oddbod
Posts: 37
Joined: Mon Oct 10, 2016 7:56 am

Re: Correct polarity with generator

Post by oddbod » Wed Jul 18, 2018 9:07 pm

Thanks for the reply.

I was at the marina at the weekend. A friend had an earth meter that confirmed a good earth on the boat when plugged into the marina 240v, but no earth when running the generator (A Honda EU 10i). I tried to rig an earth from the genny earth but no success. However, running the genny again at the marina, although the same polarity issues were displayed on the AC panel, this time the coolbox was working!?

I will follow your advice and run the coolbox from the 12v and run the genny to keep the batteries charged up.

Thanks again.

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