Question about wiring aux fuse panel

So I'm looking to write in an aux fuse panel. I have a 12 fuse block, and want to have some ignition switched, and some constant power. What I'm wondering is if it is possible to use one relay on switched power to control all the toggles that I'd like to be ignition controlled, thus killing those relayed circuits when the truck is powered off? Anyone have a diagram that might help with this install?

 

If your fuse panel has separate bus bars for multiple 12Vdc inputs then you might do something like this.

For constant power fuses that first bus bar can be tied to battery positive. It would be advisable to place an inline fuse or circuit breaker on that connection with the rating of the fuse / circuit breaker LOWER than the rating of the wiring between the battery and fuse panel bus bar. This is so the fuse/breaker opens before the wire burns.

For switched power you can use a relay with the "control signal, pin 85" connected to a switched power source (you can find some in the fuse panel behind the coin tray). When switched power is present then battery voltage will also be present on pin 87 of the relay. In your case relay pin 87 connects to the fuse panel's second bus bar. You still need to follow the precautions mentioned above for all connections between the battery, relay, and the fuse panel bus bar. In addition the relay should be rated for the expected current draw of ALL the switched power accessories you're running from that fuse block. For safety reasons I'd allow for at least 20-30% margin on the relay.

If you want you can use the same fuse / circuit breaker to connect to the first bus bar and the relay pin 30.

The connections to relay pins 85 and 86 are very low current thus the 2 amp fuse. Even a 1 amp fuse would work. You can get away with thinner wire (rated for 3 amps or greater) for these connections.

If your fuse block has only a single bus bar for all the fuses you'll probably need to consider a second fuse block.

 

I only have a single bus on my panel, and I'm not opposed to swapping it for a dual bus. Just wanted to see if this was a safe alternative. I'm thinking if my accessories are relayed through individual toggles, than by powering those toggles through switched power it will then deactivate the relay. I drew what I think I'm trying to explain

 

Yes. That will work for what you want.

 

just make sure you get a large enough relay if you are going to power a bunch of items.

 

So any of those branches from the fuse panel will have its own relay for each accessory, i just wanted to get some insight if wiring several toggles will be ok on one add a circuit. I can't imagine switches pulling that much of a draw

 

If you're planning to power your accessories directly from switched power coming off the truck's stock fuse panel I think that is a bad idea unless the accessories don't draw much current. You'll be fairly limited in what you can attach.

An add-a-fuse, when installed properly, does not allow more current than what the factory wiring is rated for. You're limited to the rating of the original fuse (and wiring) and don't forget that that fuse also supplies power to the stock item.

When I get home from work I'll draw a possible two fuse block solution.

 

Look at the picture he posted in post #3. The accessory is being powered through the Blue Sea fuse box off the battery. The add-a-fuse is running through switches to drive relay coils.

 

Correct. I'm looking to only have one add a fuse, just to power the switches to power the relay coils. I'm thinking that the switches shouldn't draw too much to overload?

 

The LED lighting on the switches will pull next to nothing. If you're using factory style push switches, add a 2nd add-a-fuse to the tail fuse. The top LED on the switch lights when the switch is turned on. The lower light will always be on if wired to the same power source as your relay coils. If you wire the lower light to the tail fuse, it will only illuminate when the parking/head lights are on.

 

Gotcha. Based on how I initially read post #6 I thought you were considering powering the accessories from switched power.

If you use the image from your post #3 and use an individual switch and relay for each switched power accessory that should work. I think the hardest part will be figuring out how to crimp all the switched power wires together.