Switched power from the ignition switch?

Wiring your boat, How to Wire Lights/Accessories, All things electrical other than actually powering your boat by electric motors.

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soedesh
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Switched power from the ignition switch?

Postby soedesh » Sat Sep 06, 2014 7:10 am

Hi, I am starting my wiring and I've studied a bunch of sources and have my design - mostly. I've installed a master battery disconnect, but my question is whether any of the circuits (gage power for example) should be switched using the ignition switch. I am guessing the answer is "no", but wanted to make sure.

Then, if using the ignition switch is recommended, how is this normally accomplished when the switch is part of an engine remote box? I know there is a tach connection on the front of the box (Mercury remote in this case) but I am not sure if there is a switched accessory feed also.

Any advice is appreciated.

Thanks,
Shawn

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Bill Edmundson
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Re: Switched power from the ignition switch?

Postby Bill Edmundson » Sat Sep 06, 2014 7:17 am

My gauges are switched power. I don't remember how I did it.

Bill
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gdcarpenter
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Re: Switched power from the ignition switch?

Postby gdcarpenter » Sat Sep 06, 2014 1:35 pm

Hi Shawn, here's the basic schematic for my ZIP. I used my 1959 Merc ignition switch, but took the switch out of the control box and mounted it in the dash switch panel. As long as you can 'tap into' the ignition wire that is 'hot' when the key is on you can splice into that lead to feed power to a fuse or fuses for items you want 'hot' only with key on.

I only used the switched fuses on my build to power the gauges and feed a power outlet.. I think it's good to have gauge power on a switched circuit so they automatically 'power up' when you start and you don't have to remember to switch them off.
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soedesh
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Re: Switched power from the ignition switch?

Postby soedesh » Sun Sep 07, 2014 4:25 am

Thanks gdcarpenter, that is really helpful. I am splicing the remote cable anyway so I will tap into the switched wire just for the gauge power. Thanks for taking the time to respond!

Shawn

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Roberta
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Re: Switched power from the ignition switch?

Postby Roberta » Sun Sep 07, 2014 5:35 am

I used a Mercontrol on my Zip. Using the lead that powers accessories on the ignition switch (lead is hot when ign. sw. turned to on position), I ran that to a relay that powers my fused buss bar. That way all my accessories like lights and gauges power up when I turn to ignition switch to on and there is no extra load on the switch. A small continuous duty relay for powering devices in cars is available at any auto parts store. I used a 35 amp relay and power the fused buss. This setup can be used for any ignition switch that has an on terminal. The relay takes the load off the ignition switch from all the things like a horn, lights, radio, etc and turns everything off when the ignition switch is turn off.

Roberta
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soedesh
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Re: Switched power from the ignition switch?

Postby soedesh » Sun Sep 07, 2014 5:41 pm

Roberta, is it OK to leave the key on when the engine is not running with older outboards?

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Re: Switched power from the ignition switch?

Postby gdcarpenter » Mon Sep 08, 2014 4:08 am

Not sure what year things changed, but my 1959 Mercury Mark35A has a magneto ignition. While most ignition switches make no internal connections in the "off" position, on older units like mine the ignition switch connects the magneto to "ground". That is what turns off the engine. Leaving the key on on systems like mine can burn out the magneto. Best to look at a wiring diagram for your controller and ignition switch.
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Roberta
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Re: Switched power from the ignition switch?

Postby Roberta » Mon Sep 08, 2014 5:13 am

soedesh wrote:Roberta, is it OK to leave the key on when the engine is not running with older outboards?


I don't know. I have the items I want on when the engine is running on the relay controlled side of my fuse block. Other items that I want to be able to switch on when the engine is off, I put on the portion of my fuse block that is energized with the key off, like the bilge pump. The Mercontrol does not have an "accessory" position. If you are using a separate ignition switch, get one that has both the on-start positions on one side of the off position and an accessory position on the other side of "off".

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".


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