Help with electrical connection on "accessory" circuit.

Already have a Power Tray mounted in my engine bay with a Blue Sea 12 circuit box and a breaker. As customary, this is directly connected to the battery.

I am looking to do something similar, on a slightly smaller scale perhaps, that will allow me to connect accessories that only come on when the ignition is turned on. Can/should this be done similarly with a direct connection to power but activated by a single higher amperage relay that trips when ignition is activated or is there an existing connection somewhere that I might be able to utilize?

Power taps from a fuse box are of no interest. It's just not clean nor proper for what I'm doing.

I'd appreciate any input on the matter!

 

If you want a fuse box like that, You should use power direct from battery through a relay that has its coil connected to an ignition circuit.

The other option you have is to use power from that unit through a relay to the accessory. You can obviously use one fused circuit for a few accessories as long as you are fused and cabled appropriately.

You can also take a few of those circuits and make them only power with ignition, but that requires modifying the busbar in that fuse box.

One last item, I hope the nevative of that fuse box is running to the chassis and NOT the battery. If to battery, you should move it to chassis.

 

Thanks for the reply.

Ground on my tray set-up goes to chassis ground so it's proper. Thanks for asking.

I guess what I was wondering on the accessory set-up was whether there was a regular "go-to" accessory connection that was an easy access or whatever. Just trying to not 'reinvent the wheel' as I get into this.

 

I use the cig socket circuit to power the relay coils on mine. But accessory fuse box is under the dash, can’t remember if the OEM main fuse for that is dash fuse box or engine bay fuse box.

 

That's a good idea! Not a real critical circuit to tie into. I'm not opposed to having that set-up in the cab but I'll consider that as I plan this out.

 

If you don’t need all 12 fuses to be battery you could switch out the block to this

https://www.bluesea.com/products/5032/ST_Blade_Split_Bus_Fuse_Block

Gives you 6 fuses on 2 different circuits, so one will can be battery and one ignition powered.

 

Another option would be to use a RTMR. It will be a bit more $ (and time cutting a hole in the Power Tray). But, it will give you a pretty clean install with constant and relay controlled circuits. Use one add a fuse on an ign circuit to trip the first relay and run the other 4 relays off the first. This will put the smallest load on factory wiring to control 4 relays. You can run the trigger wires into the cab to aux switches to be able to manually control individual circuits when truck is on and have them all shut off when you turn the truck off.

 

This poses an interesting option. Thanks for bringing this up. I'm going to look deeper into this.

 

The RTMR is also weather resistant. You won't have to worry as much about getting the fuses/relays wet when cleaning the engine bay.

 

Tap into a non critical ignition switched circuit such as a cigar lighter or the like, use that to positively trigger a relay/solenoid. Wire that solenoid contact to another smaller fuse block.

 

I don't have an aux fuse panel inside, just under the hood. However for the internal stuff I just tapped fuses. I tapped the cig 9v for a USB on the left side of the wheel in the dummy slot and then tapped my tail lights which are the illumination lights for my switches. They come on with the rest of the dash.

I feel like there's more than two tapped fuses... But my brains been concussed too many times. Just watch the amps. The light bars are directly wired through the fuse panel under the hood but the breaker is nice for people who don't realize my bars and pods will come on without the ignition.

 

A couple notations for switches and relays.
Switches: some of the switch blanks have pigtails for OE systems that your truck isn't using. Find your illumination circuit in these pigtails instead of tapping into a circuit that is in use by another switch.
Relays: the use of non-weatherproof relays can cause issues. Moisture & dust can get into the relays causing corrosion and buildup on the contacts which might eventually cause the circuit to close and activate the accessory without the switch being flipped. For horns, the horn will randomly activate until enough heat builds up to dry out the contact until enough corrosion occurs to permanently bridge the gap. For lights, you will often have the lights glowing at a reduced power which may not be noticable while driving or during the day while parked.