HID Relay
 

How many of you run HID Relay with your diode dynamics HID Kit?

-35W ONLY PLEASE

Anyone answering should also include the wattage of the kit they're running.

I have a 35w plug and play kit that I bought locally (not diode dynamics) with no relay and it's been 100% fine.

Same here. Plug and play, no issues.

I run the relay. They recommend it with their product, so why not.

Our HID kits does not require running a relay harness. Our ballasts are engineered to run as a standalone unit without the need for relay harnesses on the FR-S. :D

Relay harnesses are usually required for high/low beam (dual beam) HID headlights (Bi-Xenon). :w00t:

Relay harnesses are safety measures, preventing you from overloading (overheating > melting) the factory wires when the ballast ignites the HID bulb (which requires a lot of voltage).

Think about it:

Harness = $10 - $50 and maybe an hour or two of your time

Factory wires = $$$ probably around $2k

True, you have a good point.

Whether it is needed again depends on how good the ballasts are, that is, whether it has measures to mitigate in rush current on initial startup.

Nevertheless it doesn't hurt to have a relay harness but we simply think "do not do more than what is needed."

At the end of the day, a relay may save the day if the HID kit (depending on the ballasts again) recommends having a relay harness. Certainly doesn't hurt to have a relay harness to be frank. :) just my 2 cents

Harness = 2-15min. The latter if you barely open the hood of your car only to check oil

For now. :)

It's always better to be safe than sorry.

If the wiring in the car isn't capable of handling the current needed for 35w ballasts, then something is probably faulty. 35w is less than 3 amps per ballast (watts = volts * amps), and those circuits should be able to easily handle 6 amps. I haven't checked the fuse, but it's probably 10a or 15a, which is well above the current needs for a 35w setup.

there's a surge of power when the ballasts are fired, which then stabilizes down to lower levels immediately. it's this surge that kills the wires.

Sent from my Nexus 5 using Tapatalk

Let's look at some electrical reasoning:

A well-designed digital 35W ballast should only draw a maximum (including startup surge) of 8 amps at 12.8V. This is more than a 55W incandescent bulb, which will draw, by definition, 4.3A at 12.8 volts.

Your factory wiring is designed to handle at least 10 amps, (10A fuse) but any time you are drawing more power than the factory, you should run a separate wiring harness to provide full power supply. No, you might not have to to allow the HID kit to work, but it's just a good idea. And if for some reason the ballast goes out (common occurrence with cheaper kits) you don't want to worry about it malfunctioning, drawing too much power, and killing factory wiring.

HOWEVER... 99% of 35W ballasts on the market are not well-designed, and can draw over 15A at startup. This is well over the limitations of the factory wiring. You're not going to burn up any wires, but you might damage the BCM, the motherboard of your electrical system, which is usually around $1000 to replace.

Now, before you run out and check the label on your ballast for max amperage draw, know that those labels are just arbitrary numbers most of the time. In fact, you might not even be running a 35W kit. Most "35W" ballasts only actually output around 31W. Read more here.

If you're running a "55W" kit (which we do not recommend, in any scenario) you had better be using a relay harness.

@KI_ZN6 , can you tell me more about the specific engineering you did for the FR-S? This vehicle's power distribution system is no different than any other Asian import, so there's nothing specifically required for it, electrically, unlike Dodge vehicles, for example. Are you saying that your ballast is designed to draw less than 4.3A at startup?

Paul

It's not just the wiring here, a nice strong power source for the ballasts to function properly.


Also, another fun fact is that some OEM ballasts can pull over 10 amps on startup. I've never had the chance to compare the wiring between the FRS and BRZ, but I bet the BRZ has beefier wiring for the headlights...

Is it safe to assume that a 35W without relay won't fry anything in the long term? (Diode Dynamic HID and HID_Powerhouse)
Noob question: Say starting amp is 6Amp.. 2Ballst.. That's 12amp no?