100W+ headlights in an S5

[soldave]

Wondering if the stock harness will handle 120W or 130W headlights in an FC or not. We all know how brittle the stock wiring harness is in these cars and am thinking a lot more power in the lights is gonna heat up those wires quite a bit more. But is it an excessive amount?

If it is, then is a parallel wiring system what you'd need to get it working, right? Bear with me as I'm not the most electrical-minded guy but want to make sure I'm thinking this through right. Looking at the wiring diagrams it looks like I'd need to get a 30A inline fuse running from the battery. This would then go through 2 new relays alongside the 2 original ones (the signal wires being spliced so it all comes in at the same time) and then a ground from the 2 lights back to the battery or a suitable grounding point.

Does that sounds vaguely sane or am I completely off?

[NoDOHC]

The simplest solution to increase current is a small 12V Bosch sealed relay. This will allow the headlight to draw current directly from the battery, while keeping the functionality identical to the factory configuration.

I would be a little worried about the wiring, but the switch would be a larger concern (20 Amps is a lot through the light switch).

[TitaniumTT]

Don't do it. As stated before, the wiring is old, the relays that were used are known to be fragile. To correct NoDOHC though, the switch only provides a latch to gnd to trigger the headlamp relay. Then the bright switch latchs to gnd to control the dimmer relay. Dimmer relay in this instance meaning dim from high beam to low beam.

So, if I were you, I would get in touch with Susquehanna motorsports, I'm sure the spelling is FUBAR, but you can get them @ Rallylights.com. They have a connector that will plug into the female side of the H4 connector. This way, you can steal power from wherever, use the connector to make your own plug and play harness. This way, you're not cutting ANY of the factory wiring. probably the best thing for the not so electrically minded person. Sorry, but I've repaired so many hack wiring jobs in the past, it's just not really worth it.

[NoDOHC]

Good call there TitaniumTT, I meant to reference the post that I had read, but it must have been elsewhere or has been deleted, as I couldn't find it. I meant to replace the existing relays with the Bosch style and leave the wiring intact (there is a writeup somewhere that shows how to do this).

Then the only wiring that may need to be replaced is merely from the fuse block by the shock tower to the new relay (not too bad).

An interesting question would be why the stock headlamps are inadequate? Do you intend to rally race at night?

edit: I was wrong about the switch, I guess it does just drive the relay coil, so why does it fail?

[TitaniumTT]

I've never seen a headlight switch fail. If they do it could be for a few reasons, the most likely is a bad gnd feeding the switch. The gnd system on the FC is pretty abismal.

The stock sealed beam lights are aweful as well. The first thing that I do to any vehicle that I buy with those H4 sealed beams, and I have quite a few actually, my Jeeps also use the same headlight and one of the first things all of us jeepers do is swap those POS's out for some IPF's or Hella H4 housings. Even with the same 50-60 watt bulb, the improvement is incredible.

[soldave]

An interesting question would be why the stock headlamps are inadequate? Do you intend to rally race at night?

The stock ones might be fine; I'm just wanting to do some research beforehand. Have got a pair of Raybrig Multi Reflector headlight housings and if I could make myself a little money and afford to keep them, and if so if the stock headlamps will be good or the higher watt ones would be better.

And the car is just used for a "fun" car, mainly doing touge runs and the like at night.

[RETed]

Sorry, I gotta ask this...

Why aren't you running HID's?
The prices have really come down, and current draw is minimal to what you're looking at.


-Ted

[soldave]

Well to be honest I am considering something like this:
http://cgi.ebay.co.uk/35W-BI-XENON-HID-KIT-H4-9003-HB2-Hi-Lo-6000K-24V-/280559231028?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4152a22034

Or this
http://cgi.ebay.co.uk/2x-HID-BALLAST-XENON-BULBS-KIT-35W-H4-1-6000K-Headlight-/120610722678?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1c14f59376