grounding running lights

[Getting_started]

I wired up running lights on a friends boat last week and did a quick hookup for testing. I just ran a hot and ground wire from the battery to the lights and he went out night fishing to test things out. An hour after turning the lights on, his motor died while trolling. It's in the shop now getting looked at. There appears to be a spark, but maybe not strong enough and the shop says a fuse was blown and possible problem with the stator.

I would normally have run the ground from the lights to the boat itself rather than back to the battery. Do you think this caused the electrical problem with the motor ?

 

[BaileysBoat]

Re: grounding running lights

I would normally have run the ground from the lights to the boat itself rather than back to the battery.

The above is the wrong way, so you got part of it right. Always a separate ground/bus bar. I assume you are tallking about an aluminum boat? You ran direct power to lights, no fuse or switch?
Not a good idea, a short could cause an electrical fire.

In any event, its not likely you caused any damage to the motor, but not much info on the boat/motor setup. What is the fuse that blew?

 

[Getting_started]

Re: grounding running lights

I don't have a lot of detail from the mechanic yet about the fuse, but apparently, Yamaha has an inline fuse in the outboard motor. From the sounds of what they are testing it's after the regulator (?).


It is an aluminum boat - 17 foot Princecraft.
I would normally have a switch in the light circuit, but didn't have one on hand - it was a bit of a rush job to get some lights working. Would the ground bar/bus be wired back to the battery. I've never had that kind of a setup on any of my boats (mostly small steel hulls - 14 - 22 ').

 

[Silvertip]

Re: grounding running lights

You do not ground things to an aluminum hull but I will hit on that a little later. Yes, you install a ground bus at a convenient point up front, usually at the helm. That ground bus connects to the negative terminal of the battery by a larger #10 or #8 gauge wire and all accessories are grounded to the bus or directly to the battery. The positive feed to the fuse/breaker panel from the battery uses the same size wire.

Now back to grounding to the hull. The minute you bolt an outboard to an aluminum hull you create a ground path from the large negative battery cable to the hull via the engine block. The problem isn't so much grounding to the hull as it is having many separate ground points on the hull.

It is very unlikely you did any damage to the electrical system on the engine.

 

[Getting_started]

Re: grounding running lights

Thanks for the response. It sounds like there is no difference between grounding to a separate ground bar (wired back to the battery), or going directly to the battery.

I'll rig up a fuse / switch panel, or buy one and get things cleaned up.. One thing that is bothering me is that he said his battery was really hot the night his engine failed. He had been running the lights for about an hour (just a 12 volt bow and stern light).

 

[rwidman]

Re: grounding running lights

It sounds like there is no difference between grounding to a separate ground bar (wired back to the battery), or going directly to the battery.

Electrically there is no difference, but it's common practice to run a (fused) positive conductor from the battery to a distribution panel at the helm and a negative conductor to a negative buss bar at the helm.

You don't want a dozen connections to the battery.

An, unlike a car or truck, don't attempt to use a metal hull as a common negative conductor. Use insulated wires.

 

[NYBo]

Re: grounding running lights

One thing that is bothering me is that he said his battery was really hot the night his engine failed. He had been running the lights for about an hour (just a 12 volt bow and stern light).

This should have zero to do with your quickie wiring job. Sounds like the mechanic is on the right track checking the regulator and stator.