Jump to content

Stray 12Volts


antonywardle

Recommended Posts

Hi everyone

I've been trying to track down 12 volts that shows up on the multimeter when I go from the + on the battery to the hull. (Hull is a plate boat). I've disconnected everything in a few attempts to sort this out. The only thing I can think of is that the engine boat to the transom aren't insulated.

 

Could this be the cause? Does an outboat been to be insulated from the hull? I have the backing board between the engine and the transom but the bolts simply bolt on.

thanks

 

 

Link to comment
Share on other sites

They have just used the hull as an earth return. The engine electrics will be earthed through the motor as well, motor won't be insulated from hull.

 

Problem with running a hull earthed system in the possibility of electrolisis and the resulting corrosion.

  • Like 1
Link to comment
Share on other sites

No... what you are seeing is common to every aluminium boat I have seen.

It is not a problem unless the hull IS USED as part of an electrical circuit.

EVERY electrical device on the boat should have a +ve and a -ve wire going to it..  The -ve wire MUST be connected back to the battery  either directly or by a joining to another cable.

Using the body as a part of the circuit is OK for cars... but not for boats.

 

  • Like 2
Link to comment
Share on other sites

41 minutes ago, dmck said:

It is not a problem unless the hull IS USED as part of an electrical circuit.

EVERY electrical device on the boat should have a +ve and a -ve wire going to it..  The -ve wire MUST be connected back to the battery  either directly or by a joining to another cable.

@dmck has said it MOST succinctly.  100% agree. 

If you want further confirmation please look at the post by "kmorin" on the following link - he goes to great lengths to explain exactly what our Don has summarised in 3 lines...   http://www.aluminumalloyboats.com/viewtopic.php?f=3&t=2260&view=previous

Do earth the -ve of the battery to the hull (similarly the motor will have a -ve attachment somewhere on the head and then to the hull through the mounting bolts).

Do NOT use the hull as part of the electric circuit (run a separate -ve and +ve wire to every device). 

With this set up, if a stray current does appear, it would follow the path of least resistance (the dedicated -ve wire) back to the battery rather then use the hull. 

Cheers Zoran

  • Like 2
Link to comment
Share on other sites

1 hour ago, antonywardle said:

I have bus bars that are insulated from the hull and that's where all of my devices go to.

...as long as every device has its own -ve and +ve path back to the battery (ie. no device uses the hull as a -ve path).

Cheers Z

Edited by zmk1962
  • Like 1
  • Thanks 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...