I’m fairly new to both the worlds of electronics and plumbing, but over the last week I’ve been doing research in order to install a train horn in my car (05 mini cooper s) and have learned quite a bit.
I’ve been reading posts on various forums over the last few days, and I seem to remember every now and then someone mentioning the importance of using a relay switch. I’m not familiar with the purpose or function of a relay switch, but they seem to be absent in the official schematics for the kit I’m looking at.
Could someone please explain to me exactly what a relay does, and whether or not it would be important in this set up?
Welcome to the forum. That Shocker kit is a good way to get started. We recently had a similar question in relation to that kit. You will find some explanations as part of that post here: http://www.trainhornforums.com/showthread.php?t=6366
Don’t hesitate to ask if you got more questions after reading the above link.
So at this point, I guess what I’m wondering is, how much of a drain the compressor would put on the battery. The battery on the mini cooper is in the trunk, which is also where I’m going to be keeping the air compressor, so that’s pretty convenient. However, what kind of reduction am I going to see in battery life wiring up straight to the battery?
That might be a little clearer on how the system should work.
you can activate the system using a keyed source, I would get a fuse tap and go inline in your fuse box with your accessory/cigar plug. Using a fuse tap will give your switch circuit a fuse.
There is a minor difference between this wiring diagram and the kit you want. In the diagram i linked to it shows a pressure switch between your keyed power source and post 86 on the relay. On the kit your looking at the pressure switch looks to be pre-wired between post 87 and your compressor.
It will work the same way either way you wire it.
Hope this helps and doesn’t make you more confused!!!
Am I wrong, or does that diagram show me wiring to the battery AND an ignition power source? Should I just wire to the ignition power source from the 86 on the relay and ignore the 30 part? Sorry, I’m almost a complete noob to the world of electronics :o
You are correct, with a relay you use the battery AND the ignition source. The point being you can keep smaller guage/low amp wire running to your switch/ignition source while you keep your high amp wire running from your battery to the relay to the compressor.
If you dont use a relay then you will need to find switches rated to handle the load of the compressor.
Also most likely there are no ignition sources rated to handle the 25-35 amps your compressor will need to run. Which is another good reason for a relay.
Viair doesn’t include a relay in this pre-packaged compressor/tank combo (20005 model). However, it is always recommended.
There is an in-line fuse holder and a 35 amp fuse included in this particular kit.
We always recommend running an ignition source power wire (which is included in the kit also) along with never running the compressor without the vehicle running.
