Proper 12V Auxiliary LED Wiring How To!

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Sputnik

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Good info here, thank you.
I have a question about hooking up the auxiliary fuse/relay panel.
If I do a basic connection from the aux fuse block to the battery then all the circuits will be hot all the time, correct? If I want the aux panel to only be hot once the key is in and the ignition at or past ACC then I would have to hook the main positive some where else...but where?
Or is doing that even feasible?
Thanks for any advice.
 

slomatt

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If you want your aux panel to only be powered when the key is on you can use a relay to switch your aux panel on and off and control the relay using a +12v signal switched by the key.

1. Put your main fuse as close to the + battery terminal as possible.
2. Connect the other side of the fuse to pin 30 on a relay.
3. Connect pin 87 of the relay to your aux panel.

The main fuse and relay need to both be sized large enough to support your intended loads. Then you can pick a wire gauge that can support the maximum current, determined by the fuse size. For example, if you anticipate a max 40A of loads connected to the aux panel your fuse would need to be larger than that (say 50A) and your relay would need to be able to support at least whatever the fuse is rated for. You can then use a chart like this one to look up the proper wire size (AWG) for the max current and wire length.

The last step is to use a low current switched signal to drive the relay. This will likely be the tricky part. One option would be to tap into the accessory circuit (cigarette lighter) either in the car or at the fuse block under the hood. In most vehicles this is switched +12v, and you would hook it to pin 86 on the relay and then ground pin 85.

The numbering system for relays is a bit confusing, but the important thing to keep in mind is that pins 85 and 86 power an electromagnet that when energized activates a switch that connects pins 30 and 87.
 
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Sputnik

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If you want your aux panel to only be powered when the key is on you can use a relay to switch your aux panel on and off and control the relay using a +12v signal switched by the key.

1. Put your main fuse as close to the + battery terminal as possible.
2. Connect the other side of the fuse to pin 30 on a relay.
3. Connect pin 87 of the relay to your aux panel.

The main fuse and relay need to both be sized large enough to support your intended loads. Then you can pick a wire gauge that can support the maximum current, determined by the fuse size. For example, if you anticipate a max 40A of loads connected to the aux panel your fuse would need to be larger than that (say 50A) and your relay would need to be able to support at least whatever the fuse is rated for. You can then use a chart like this one to look up the proper wire size (AWG) for the max current and wire length.

The last step is to use a low current switched signal to drive the relay. This will likely be the tricky part. One option would be to tap into the accessory circuit (cigarette lighter) either in the car or at the fuse block under the hood. In most vehicles this is switched +12v, and you would hook it to pin 86 on the relay and then ground pin 85.

The numbering system for relays is a bit confusing, but the important thing to keep in mind is that pins 85 and 86 power an electromagnet that when energized activates a switch that connects pins 30 and 87.
Thank you, after looking at some info about relays and your explanation I think I get it now. I’ll need a relay, an anl fuse and one of those add a circuit things.
I can see this working now. Thanks again.
 
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How did you wire the yellow and white wires to the switchpanel?

Ideally, I would like it on the dimmest backlight to come one with headlights and the red 12v to switched power.
But no one seems to know how to wire the yellow and white wires?
 

Sputnik

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What is 87a on a five pin relay for?
I’ll assume I’d want a four pin relay in any case.
Or can I use the five pin and just pull that wire out, not use it?
thanks again for answering my dumb questions
 

slomatt

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I think the 87a pin is "normally closed", which means that it is connected to pin 30 when the coil (pins 85 and 86) is not energized. Or in other words, 30 is connected to 87a when the relay is "off" and to 87 when the relay is "on".
 
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Lanlubber In Remembrance

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You're welcome and good luck!
I'm happy with the info too. I've been looking at that gland on Amazon for six months while trying to figure a way to enter my rig with my solar wires and not look amateurish. Also I want a way to get into the rig with my rack lighting wires without monkey rigging it through the A or B pillar posts. That grand is an answer to both wiring fixes. I plan to connect them to a panel inside the rig to power up everything I plan to hook up.
Awhile back @007 posted some pictures of his rig wiring and it was great. We need him to come back and show us again.
 

Lanlubber In Remembrance

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I decided to go with bulkhead fittings for my RR Lights...I wanted something that wouldn’t be obtrusive when I remove my rack.
WF28 high Voltage Power Cable 7pin led Connector, Current 25A Voltage 500V Aviation Bulkhead Connector Plug Socket(7 pin)
When I see you I will want to talk to you about this and a lot about radios ect. :-)
 

Mrainbolt88

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I decided to go with bulkhead fittings for my RR Lights...I wanted something that wouldn’t be obtrusive when I remove my rack.
WF28 high Voltage Power Cable 7pin led Connector, Current 25A Voltage 500V Aviation Bulkhead Connector Plug Socket(7 pin)
When I see you I will want to talk to you about this and a lot about radios ect. :-)
I've ordered a very similar fitting off Amazon for the same purpose. How did yours turn out? Any tips?
 

M Rose

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I've ordered a very similar fitting off Amazon for the same purpose. How did yours turn out? Any tips?
It was a lot taller than I expected... as for tips... hot soldering iron... and take your time... make your harness about 2’ longer than you think you need and start feeding the harness from the roof to where ever your relay panel is... for the light side of the harness, again lay the wires from the lights to the harness and give yourself about 2’ of extra wire. Wire the lights in place then solder the bulkhead fitting last trimming the wires to length at the connector... lastly don’t use silicone to seal the connector to the roof as this will induce leaks with the supplied rubber gasket.
 

Mrainbolt88

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I've ordered a very similar fitting off Amazon for the same purpose. How did yours turn out? Any tips?
It was a lot taller than I expected... as for tips... hot soldering iron... and take your time... make your harness about 2’ longer than you think you need and start feeding the harness from the roof to where ever your relay panel is... for the light side of the harness, again lay the wires from the lights to the harness and give yourself about 2’ of extra wire. Wire the lights in place then solder the bulkhead fitting last trimming the wires to length at the connector... lastly don’t use silicone to seal the connector to the roof as this will induce leaks with the supplied rubber gasket.
Thank you! Very appreciated
 
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Sputnik

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Another big thanks for the help. I’ve got my aux fuse box wired in through a circuit breaker and a 60a relay and it’s working just as desired. I just didn’t like the idea of having it powered at all times and this shuts it off once the key is turned off.