Drain wire for my gps

[Fishfreek]

I just picked up my Raymarine Dragonfly 5 Pro. The power cable has 3 wires in it ( positive, negative and what they call drain wire ) the instructions say to mount the drain wire to the boats ground or if no ground then to the negative side.

So I am looking for suggestions on where to put the wire. It' wire #2 in the picture.

 

[ADIBOO]

It's a chassis ground (probably for EMI), mount it to the hull of the boat.

 

[richg99]

I wouldn't ground anything to a metal hulled boat, especially if it was kept in the water for any period of time.

If I had that device, I'd run the "drain" wire all of the way back to the grounding post on your battery.
richg99

 

[Fishfreek]

I wasn't sure about grounding it to the boat. The battery is about a foot away. I had a battery box built into my tiller console so that I have a dedicated battery just for the gps and lights.

 

[ADIBOO]

Don't confuse a ground/drain wire with a negative wire, they are two different things. The negative wire is used to power the device, the ground/drain is to remove RF and EMI from the circuitry of the device so it works better. Attaching the drain to the hull isn't going to hurt anything on your boat.

 

[richg99]

Every day I learn something new on this site.

richg99

 

[Fishfreek]

Me 2.......

That's why I ask

 

[Bob Landry]

Don't confuse a ground/drain wire with a negative wire, they are two different things. The negative wire is used to power the device, the ground/drain is to remove RF and EMI from the circuitry of the device so it works better. Attaching the drain to the hull isn't going to hurt anything on your boat.

Not so.

Ground and negative are one and the same. A look at just about any wiring schematic or electronic wiring harness will verify that.
If your instructions say it can be grounded to a battery terminal, I would do that. When you start connecting grounds to a metal boat hull you start increasing the possibility of setting up differences in potential which can lead to undesirable galvanic activity
.

 

[ADIBOO]

Don't confuse a ground/drain wire with a negative wire, they are two different things. The negative wire is used to power the device, the ground/drain is to remove RF and EMI from the circuitry of the device so it works better. Attaching the drain to the hull isn't going to hurt anything on your boat.

Not so.

Ground and negative are one and the same. A look at just about any wiring schematic or electronic wiring harness will verify that.
If your instructions say it can be grounded to a battery terminal, I would do that. When you start connecting grounds to a metal boat hull you start increasing the possibility of setting up differences in potential which can lead to undesirable galvanic activity
.

Do a quick Google search for RF drain. All this drain wire is doing is taking any EMI or RF from the device, and dispersing of it, which would be best accomplished by use of a ground (metal boat in water). Yes the negative battery terminal can work, but is not the preferred method.

As far as difference of potential and corrosion, even if this was left in the water all its life and the device was powered the whole time too, it's not gonna create any significant corrosion problems.

 

[JMichael]

I think the problem is the way you worded it. It should read like this I believe.

Don't confuse a drain wire with a ground/negative wire, they are two different things.

 

[Bob Landry]

In a marine application and assuming it's a negative ground and not a positive ground system, I can't think of any application where grounds from equipment is not going to be connected to battery negative.

 

[Fishfreek]

I finally dug up something about this on the Raymarine tech forum


Welcome to the Raymarine Technical Forum,

Should the vessel be equipped with a bonding plate and bonding cable, then the drain leads should be joined and connected to the bonding cable.  Should the vessel not be equipped with a bonding cable and be equipped with an inboard engine, then the drain leads from Raymarine products should be joined and connected to the engine block.  Should the vessel not be equipped with a bonding cable or inboard engine, then the drain leads from Raymarine products should be joined and connected to the negative post of the battery.

 

[SumDumGuy]

wired my dragonfly drain to the neg terminal.... no issues.

 

[richg99]

Since there are a multitude of small outboard driven boats, versus a much smaller number of sailboat and larger inboard powered yachts....you'd think that Raymarine would make this statement far more prominent. Sheesh.... richg99

..... Should the vessel not be equipped with a bonding cable or inboard engine, then the drain leads from Raymarine products should be joined and connected to the negative post of the battery........