re-wiring issues

[kevsbox]

Hi all

Merry xmas and a happy new year to one and all

I am getting an annoying and worrying issue with the electrics on my Centaur. The switches for lights, radio, instruments etc etc have been moved to a new position which is easier to view and get to. Below is a photo of the project when it was half completed, there is now a 4 gang set below with 3 switches in use.



What I am finding is this, most of the time when I turn things on they work fine but every now and then the switches dim and sometimes they all stop working. The lights will also dim and if the VHF is on it will go off. The 2 leisure batteries and 1 starter are all less than 2 years old.

Also I noticed that today the VHF has a flashing b next to the Channel number display. The set is a ICOM IC-M59Euro, could this be related?

The other strange happening was a couple of days ago I started the engine (Beta 20) and ran her for a while then when I pressed the stop button nothing happened and the engine would not stop. After a few frantic minutes of checking wires etc the stop button worked. Today it worked fine.

The dimming issue has happened in the past before I moved the switches but appears to be more frequent now, almost as though I have touched something dodgy and made it worse. Any ideas on what is happening here please, is this a loose live wire or a loose neg wire?

 

[Aurai]

My suggested check, is to test voltage across service battery terminals and then follow this all the way through your install. To ensure, or not, you are getting the same voltage through the whole system. As in battery to switch to accessory. As for connections, do check every single one, to satisfy you that is not the problem if nothing else. You can get back to me via pm of you have done that and still have the issues. Ta

 

[penberth3]

.......The dimming issue has happened in the past before I moved the switches but appears to be more frequent now, almost as though I have touched something dodgy and made it worse. Any ideas on what is happening here please, is this a loose live wire or a loose neg wire?

This is often the problem - the negative/return side. (Don't call it "earth" on here!!!)

Carry on as Aurai said in Post #2, methodically end to end. Don't be afraid to give wires and connections a gentle pull, that might show a dodgy contact somewhere.

 

[William_H]

If you can not find a bad connection try fitting another stout wire between the battery negative and your switch negative bus bar. This may eliminate the problem.
It it does not then try a similar wire battery positive to switch pos common. Those tests should isolate prolem to pos or neg lines. Any isolation switch could ahve bad contacts also. ol'will

 

[Boathook]

Seems like a dodgy connection between the batteries and switchboard. When checking wires give them a gentle tug to see whether any are lose in the connectors.

 

[afterpegassus]

Seems like a dodgy connection between the batteries and switchboard. When checking wires give them a gentle tug to see whether any are lose in the connectors.

Dodgy 3rd rock from the sun.
Duplicate the connection as per Will H's suggestion

 

[PaulRainbow]

As per post #3, more likely a Negative issue.

 

[Stemar]

I'm with the others, my plan A would be to give a good clean to all the connections, starting with the battery terminals and the "earth" to the engine block.

Measuring voltage may not tell you much, because the resistance of a volt meter is much higher than that of a poor enough connection to cause problems in a 12v system.

 

[kevsbox]

Thanks all, good advice. I will be back on board on Saturday so I will check as suggested here

 

[Rhylsailer99]

I had the exact same problem with my Cobra 850.
If I measured the voltage across the lights it would read over12v, but as soon as a load went on, the volts would drop dramatically.
In the end I just ripped everything out and started from scratch, replacing every wire in the boat with new.

 

[kevsbox]

I braved the weather and went to the yacht today. Then I took off all the wires on the switch box apart from the VHF Radio. With the radio switch off I measured the voltage across the pos and neg into the switch box and I got over 12v, the I turned the radio switch on. The radio did not power up and I measured the voltage at 4.5v so a few more cables to check at the weekend.
The first will be the one on this little set which goes down to the engine and meets up with the 2 neg cables from the batteries.


I am also thinking about replacing the large neg cable which goes from here

Under the engine to here


Any thoughts please

 

[Boathook]

There doesn't seem to be a big cable feeding the negative stud (first picture) which won't help matters when a few items are on.

 

[andsarkit]

I also had an M6 stud for all the domestic negatives. This was fine when I only had nav lights and cabin lights but as I added more gadgets the stack of ring terminals increased to about 12 high. It was difficult to get enough compression to guarantee a good connection and I have now changed it to a bus bar.
Unless you are drawing a lot of current the voltage drop in the wires will probably not be significant but corroded connections will soon stop your equipment from working. If possible I try to keep all connections inside an IP66 box with cable glands even inside the cabin as dampness can still get to the electrics. These boxes are really cheap now so you might as well make use of them.

 

[VicS]

I braved the weather and went to the yacht today.
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Any thoughts please

To begin with , there are too many connections on the negative power stud

As Andsarkit suggests replace it with a bus bar

.

 

[kevsbox]

Thanks all, I m using bus bars in the new switch box but this stud is on the other side, however I do have spare bar so I will do that this weekend and the cable feeding down to the engine will be bigger also