There are lots of reasons to run one but just think how much easier it is to replace a $30 harness than trying to fix stock wiring if something does go wrong. Initial start up loads can be very high. The harness draws straight from the battery instead of the thin stock wires.
Even if you dont get a well made one. Even the 7$ shipped from ebay with a single relay is better than having it run directly from your stock harness. Ofc thats if you dont have 30$ to spend but want to have something as a safety.
I just ordered a cheap one off eBay for now to hold me over. You only need one right? And also, do you unplug the battery to install it? If so does it reset all the oil change life and stuff like that?
You only need one harness with at least a relay that had 40A/12VDC rating and power inline 30A rated fuse. As a experienced modder and engineer doing this mod I don't feel like it necessary to remove the battery terminal if you have all your switches off and know what to look out for when you are installing. But for a fail safe project, removing the neg terminal should be practiced. iMid will not be reset because there's a backup battery for the maintenance minder. Can't say the same for clocks and radio.
Yeah that's what I orderd. It was $6.99 lol. Now if I do hids in my fogs can I run another relay? Or would one just be fine as long as the headlights are taken care of?
A relay ensures a proper 12V for the HID's as the power is coming right off the battery rather than the vehicle wiring. Some vehicles require a relay for HID's to function properly, but the Civic you can get by without one just fine so it is purely optional if you want to use one or not.
You "CAN" run it without a relay harness and it "SHOULD" be fine but I always recommend running one. However damaging a relay harness is far less expensive than damaging your factory wiring.
That melting fuse could have also been because it was not in a water-tight housing. A bad connection could have caused it to arc and do the damage in the pic.
Yeah it was just taped up. "It'll be fine bro" I thought it had been in a holder when it got installed. I've since switched to sealed holders only and install stuff myself so I know its done right. Things you learn as you go. That one was quite a few years ago.
EDIT: Quick shout out here... If you guys are thinking about ordering from xenon depot - DO IT! I've ordered several things from them and they've all been high quality and the guys are extremely helpful. Some of the best customer service I've ever experienced.