Relay wiring help

[joshgar8]

Hey guys, I am about to get into some wiring in my boat and just want to make sure that the plans in my head make sense before I get to far involved.

I am planning on installing a radio, and cig lighter plug on the port side of my boat. I have two batteries, one for the engine, trim, lights, gauges, and the other it for the trolling motor (12v). I want to hook the radio and cig lighter up to the trolling motor battery so if a day in a cove runs the battery down from the radio, no worries about getting back to the dock. My question is: can I pull a small 12v wire from my master switch on the dash and the ground on the engine battery to excite a relay to energize the radio and the cig lighter plug from the 12v supplied from the trolling motor battery. I think this will work, I was just curious about running that larger 10ga positive from the trolling motor batter thru the relay that will be energized with a positive and ground from the engine battery.

I hope my question is clear enough, if not please ask away and I'll try and clear up any confusion.

Thanks,
Josh

 

[NYBo]

Re: Relay wiring help

That would work. Complicated, but it would work.

 

[joshgar8]

Re: Relay wiring help

Yea I know it's complicated, however that's the only way I can think to wire it and not have the radio on all the time from the trolling motor battery without adding yet another toggle switch to the 5 already in the dash from the factory.

I was just curious about running both batteries thru that relay without any complications.

Thanks,
Josh

 

[Silvertip]

Re: Relay wiring help

Why not wire the radio and whatever else to the troller battery. Doesn't the radio have an ON/OFF button? The accessory socket doesn't need a switch. Yes I know -- you are afraid of leaving the radio on. If that's an issue you stand the same chance of leaving the MAIN switch on. Besides, unless your radio has an external amp, you can leave the darned thing run overnight and it will not kill the starting battery. Wire it through the MASTER and go boating.

 

[glenn property of pam]

Re: Relay wiring help

a relay is designed to be a seperated remote switch. the whole idea is that the coil side and the contact side have nothing to do with each other. in the automotive and boat world they are used to increase available amps but in the industrial world they are used to switch diffrent voltages and circuits so the coil can be energized from your starting battery and anything can be run using the contact side. im guessing you want the master switch to kill all electrical items on board so when the master is turned on the relay closes. proberly over kill but nothing electrically wrong with using a relay to do that. relays come in diffrent ampage get one thats big enoght for the load.

 

[joshgar8]

Re: Relay wiring help

Glen, that's exactly what I am trying to achieve. I want to kill everything with the flip of one switch, however using two different batteries. It's sounds very complicated for what little goal I have in mind, but do to the location of the batteries, the plug and radio, and the master switch, it will be very easy to do and have a very clean install. Running the relay will allow me to pull two small long wires (18-22ga) from the master to the relay and one short big one for the plug and radio (10-12ga) making the price of the install cheaper and simpler for me to remember to turn everything off.

Thanks guys, all your info is greatly appreciated, Josh

 

[Silvertip]

Re: Relay wiring help

18 - 22 gauge wire is way too small for any circuit in a boat. It simply cannot stand the physical abuse although it could obviously handle the electrical load. 16 gauge wire is more appropriate.

 

[joshgar8]

Re: Relay wiring help

Ok thanks, I will run 16ga to activate the relay. The actual power wire going to the accessories from the relay will be 10ga.