Would it be a smart move to add a relay box like this one? I want to use it for fuel pump, cooling fans, windows and headlamps.
CK5
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Electrical question
- Thread starter Timgoheen
- Start date
Here is a similar item I've used in the past. Much cheaper than what you linked above, but smaller too. I used this to do the relay mod for Windows and headlights.
Here it is in my truck. Up above the heater box. No pictures of it in progress or up close unfortunately. It's adjustable in position with those 4 silver arms. It's attached with rivnuts here.
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Here it is in my truck. Up above the heater box. No pictures of it in progress or up close unfortunately. It's adjustable in position with those 4 silver arms. It's attached with rivnuts here.
yes, it would in fact it is necessary, for fans and fuel pump any extra lights light bars exc. I have/am using one similar to what @EvilGenius has posted. 
underside of my relay box.
underside of my relay box.
How do you calculate which circuit amperage for each component?
Go by what you're using for wire. That lately dictates what fuse to use since the fuse is there to protect the wiring.
For power windows I used 10 gauge, which is overkill. But it minimizes voltage drop and I was ok with the extra price for that.
So what fuse did you use for your windows ? What if I run 10 guage to everything?
I definitely agree with using some kind of electrical center vs screwing a bunch of relays to your firewall. The important thing is to use something quality. You don't want failures in the middle of who-knows-where because of Chinesium crimps or whatever. Crimped terminals are excellent when done right and time bombs when done poorly.
Yep, that's why I'm asking for advice
electric window are generally 30 amp fuse, OEM. Same for electric fans. When you use a relay there are 2 circuits to protect with fuses.
1st will be the Load, (the device you wish to power) this fuse will be the size needed to power device, fan fuel pump multiple lights etc.
The 2nd will be the control circuit of the relay, switched, this fuse will be low amperage 5,10,15.
The relay box linked will come with loose terminals, you will need to source wire and make your own crimps. Good crimping tool soldering iron and heat gun for shrink tube should be available when adding a relay box.
1st will be the Load, (the device you wish to power) this fuse will be the size needed to power device, fan fuel pump multiple lights etc.
The 2nd will be the control circuit of the relay, switched, this fuse will be low amperage 5,10,15.
The relay box linked will come with loose terminals, you will need to source wire and make your own crimps. Good crimping tool soldering iron and heat gun for shrink tube should be available when adding a relay box.
I used a 30 amp fuse. I came to that conclusion by referring to a table similar to this one: https://www.stevemeadedesigns.com/board/topic/1005-wirefuse-guide/
I kept the factory window wiring in place and used that to drive the control side of the new relay. The load side of the relay is the 10 gauge with 30 amp fuse
Wes, so you're saying that I will need a higher amp fuse between the relay and component, and another fuse before the relay on the switch wire ? I have no problem with wiring and soldering. I'm just trying to picture the diagram , and I want it to be right.
In the general sense, there just has to be a fuse *somewhere* protecting any given line, so not necessarily 2 required per relay. For example, if you wire a switch to the headlight circuit, which triggers a relay for fog lamps, that headlight circuit is already protected by a fuse. The problem arises when the added wiring is too small for the existing fuse rating. That's when you might need another one. The purpose of the fuse is to protect the wiring. The fuse should blow before the wire insulation would melt.
Yes you will need a fuse of appropriate size for your load. The fuse should be on power into relay side, close to source.
This image show what I mean.
This image show what I mean.
The purpose of a relay is to supply higher current to your load than most switches are rated for. Or would impractical to install, due to distance, size constraints, or just not safe to have that much current in proximity to or equipment or people.
Mostly for our purposes switch size, most will only provide 15-20 amps with out burning out. Quality today I would say closer to 15amp.
Mostly for our purposes switch size, most will only provide 15-20 amps with out burning out. Quality today I would say closer to 15amp.
I had a 3 relay weash and it was okay. I just switched over to the msd solid state relay high amp for my spal fans and plannon on doing headlights with it. So far I like how easy it is to wire but I am having some issues with it related to my temp sensor switch. Have a replacement temp switch coming to confirm its not the msd.
