Relay panel in cab

So I have wired a ton of accessories into my cab at this point, only 2 or 3 actually using relays to trigger activation. Many times I am running LED's with such low draw I am running my power right through the OTRATTW switch and haven't had any issues thus far.

Now the signal wire that typically runs into the cab to trigger the switch, that is a ground correct?

The reason I am asking is that I am working on a project where I have the ability to control 8 relays. The issue is that the relay panel is not waterproof, nether is the item controlling the relays. So I was going to mount both the controller and the relays into the cab. The relays will be merely acting as the "physical switch" just like the OTRATTW switches would.

Now my question is what is the safer route to go...

Option 1: Ground the accessory to a ground bus, and run power from the aux fuse panel, into the cab, through the relay, back out the cab, and to the accessory.

Option 2: Run a direct hot from the fuse to the accessory, and run the accessories ground, into the cab, through the relay, and to a ground bus I place next to the relays.

Option 2 seems safer, more efficient, and less risky IMO but then the accessories will always be hot. Worst comes to worse, if it accidentally grounds out on the way to the relay controller, it will just leave me with a dead battery. This makes the most sense to me, but I'd like some other opinions. Unfortunately putting the relay board in the bay right next to the battery is simply not an option.

 

Option 2 is the way I am running MOST of my accessories; especially the ones running such a low amp draw as you mentioned. Currently, I think my winch and my power inverter are the only things not drawing a constant power unless the truck is running (obvious reasons). I have had my share of dead batteries especially in the winter when it gets really cold or the temps over a few days look like a roller coaster. My stock battery lasted 4 years setup that way and then that guy's replacement lasted 2.5 years when I had to buy a new one (Sears closed all local stores and I could not use the 5 year warranty..bummer). I replaced the useless Sears battery (forgot the brand unless I go back into my build thread but it was junk) with a higher cold crank (720 IIRC) battery from autozone that was around $120 (with core exchange) with a 5 year warranty. No issues yet and it's been roughly a year.

The next plan of action for me is to switch to dual batteries in the next 2-3 years before this battery's warranty is up. Two yellow-top Optimas; one for starting and running the truck and the other for all the accessories. Never having to worry about a dead battery again (essentially) is the goal. I can still drive the truck around, do errands etc and go to the store to get a replacement battery if the accessory battery is dead.

I am not sure if that is an option for you, but certainly seems the way to go lately.

 

@cynicalrider, I don't completely understand what you are asking, so I will answer in a generic way.

All the accessory wiring I have added to my various projects over the years were wired with the accessory wired directly to ground and the hot was switched with a relay and a fuse.

A non-waterproof fuse block can be used under the hood without much worry. If you submerge your truck, you will many issues to deal with, the added fuse block being a small one, so not much worry there.

If you are set on putting the fuse block in the cab, run a single fused power wire into the cab to the fuse block. Run a power wire from each relay/fuse back through the firewall to each accessory, and ground your accessory.

Does this make sense?

What accessories are you adding? Maybe an explanation for each would be more helpful.

 

This panel will be mostly fro controlling lighting, nothing heavy duty. My heavy duty stuff (winch solenoid, compressor) are already controlled via relays and switches in the cab.

In order to understand the way I am wiring this, you kind of need to throw away the typical "wiring schematic" that is used for most vehicles, aka fuse to relay to accessory, with signal wire going to a switch.

The fuse panel is in the engine bay, right next to the battery. That is something that is not changing. The relays being used are being used in place of a mechanical switch really. So think of them as so.

My big question, though the answer seems obvious now that I started this thread is, what is safer to run into the cab, a bunch of ground wires, or a bunch of hots. My only concern is if an accessory always has a hot going to it, and the ground somehow gets worn, it could potentially turn the accessory on and kill my battery.

I mean if I REALLY wanted to do it the right way, I can run relays for every accessory (in the engine bay) and use this relay panel as my switch that controls the relays ground. But what's the point? Most of the time, these items don't draw enough amps to need that extra protection anymore.

TLR Is there a concern with a fused accessory always being HOT aside from the worry of it killing the battery?

 

Yes, that is a valid concern.

Not only draining the battery, but also starting a fire.

With the fuse block and relays mounted under the hood, the only "live" wire is from the battery to the block/relays. The accessory wires are only hot when turned on. Overall, a much safer way to wire things.

 

I agree, using relays is the "proper" way but we all know many people don't. So if you were wiring without one, what would be the safer wire to pull into the cab, ground or hot?

 

Define "safer".

If the insulation of a ground wire was to wear through and touch the firewall, you would not have a short. So, for that particular case, it is safer. But, in all my years of running power wires through the firewall, by using a grommet and filling the grommet with silicone, I have never had any problems.

Either way, aren't you going to have to pull a hot wire into the cab? You can pick up ground in the cab - almost anywhere.

Look at page 6 of my build thread. There, I added a fuse block in the cab for in-cab accessories. You might get some ideas from what I did.

The link is in my signature.

 

Very very clean wiring, I like your style. So I see that you basically just ran one block into the cab, and feed all accessories there. So you then need to feed the power to one of your hots, through the switch, and back out to the relay or accessory correct? So you have hot's both entering and exiting the cab, vs me just having a ground exiting, and my hots staying constant. But again if you properly silicone and protect your wires, plus fuse them, you should have no issues.

Technically the controller for the relays will need one low amp power source, still undecided if I want it on ignition or not though. Having it on ignition only would limit the capabilities I have with the controller, but having it be manual would eliminate the automated feel the controller is supposed to have. I suppose I can have it on ignition with a manual override if I wanted to.

 

That fuse block is for accessories inside the cab - CB radio, etc. - nothing from there goes back outside.

Not sure I understand the second part of what you said. The relays don't have controllers - just 2 +12 inputs and 2 outputs. One pair (in and out) is low amperage control feed - +12 from a switch, other side going to ground. The other pair is the high amperage line - +12 -> fuse -> relay -> accessory / ground.

 

Like I said before, this setup can’t be thought of as a typical relay setup, they are relays but they should be treated as switches. It’s unlike any typical setup on here.

So for all your accessories outside you run relays for then? The biggest issue I always ran into, especially for OTRATTW switches, when not running a relay, you need the power wire to run into and then out fo the cab to make the top light light up of the switch.

 

Im not sure about the panel in the cab, i have both my relay and fuse boxes, yes both bc i have 2, in the engine bay. i do however have my aux battery in the cab behind the passenger seat and have had zero issues with that

 

I plan to add a fuse block and relays under the hood for outside accessories.

For the switches, I will run one power wire to the switches (split it at the switches) and feed wires from each switch to either a relay or the device. Unfortunately, that is a handful of wires going through the firewall.

 

And you are running power wires into the cab for the switches right?

Yeah this is the unfortunate reality of anything when it comes to switches. I guess it's less about what you are running into the cab (power or ground) and more about how you protect those wires coming into the cab. I've got a mix currently, rock lights have a power coming from the fuse panel in the bay, into the switch into the cab, and back out to the lights, while the arb compressor is of course using a relay setup provided in their kit. Really all depends on how much whatever accessory is drawing whether not a relay is needed or not.

I think my final decision is to run powers to the accessories and run the grounds into the cab. It will lead to less wires and a cleaner setup. I really wish I could stuff this relay panel in the engine bay but it's essentially a circuit board and that won't like water.

 

Correct my switches are powered off the aux battery only but the panels are in the engine bay

 

How are you wiring the switches to be able to have both top and bottom illuminate via OTRATTW schematic? I always wired it this way using their schematic:



Which requires you to either have the power from the fuse come in then out to accessory, or out to the relay, but either way pulling power wires into and out of the cab. Or are you powering the lower led's with the aux battery (and jumping that power wire from switch to switch) and running the other power wire through the switch?

 

I jump the positive and negative together so theyre lit and only have 2 wires instead of 4 for that. as far as the power i have the 2 slot going to the fuse box and the 3 slot going to the accessory via the box. full write up for what i have is here

https://www.tacomaworld.com/threads/diy-build-and-install-a-bussmann-rtmr-fuse-relay-block.399454/

 

Okay so same way I do it, which leads to power coming into and out of the cab. Just making sure I'm not missing something new

All my switches currently:

IMG_2068 by Michael Halat, on Flickr
IMG_0146 by Michael Halat, on Flickr


Part of the reason I am exploring this new panel is because I already have too many goddamn switches.