I thought I'd be done with this project like a month ago, but like everything else, one project turns into 5, especially when you're OCD like me and want to eliminate any / all rust.

I've now replaced all my old headlight springs (not that many of them were still functioning and present to begin with), and used my stainless dremel brush to get rid of rust on the buckets, brackets, and random iron bumper parts and repainted with appropriate black rust blocker paint, I've polished the stainless headlight retainers and I think I'm ready to start wiring.

Here's the relay I went with and it's relatively simple wiring instructions: https://dapperlighting.zendesk.com/a...de+Low+Res.pdf


What I don't understand is seemingly one of the more important parts: How the heck do I actually wire this to the battery? Do I literally have to run these all the way back to the battery (not sure the wires are long enough) or is there another, an equally appropriate place to wire these in?


Adam

 

An equally important question: These hids are rated @ 55 watts; I have the stock 60 amp alternator. The stock headlights consume a constant 6 amps and the HIDs a constant 4.6 amps; BUT the headlight kit is wired such that when you turn on the high beams, both the HIDs and traditional beams are on simultaneously. (On high beams both the high and low beams are on simultaneously.)


PLUS on initial startup/warmup the HIDS pull 10 amps for a second or two....

I'm thinking that this setup means that I shouldn't even try to turn the headlights on until I replace my stock alternator with a good 140 amp setup... Any thoughts on that? Is it dangerous to even power these up to just see what they look like and to validate that they're functioning?


Adam

 

Do we know what year your car is?

 

1979

 

There are a couple places you can get power for the headlights. One is at the starter at the connection with the huge red wire that leads direct to the battery.

You can also tap in at the alternator via the stud with the single red wire and little rubber cover.

Regardless you MUST provide circuit protection (something I don't see in that schematic). A self-resetting (thermal) circuit breaker is the circuit protection of choice for every vehicle manufacturer I know of.

Regarding power it seems that you're confusing watts with amps. You say that the HIDs draw 55 watts and that you have the stock 60-amp alternator. At 13V output a 60A alternator produces about (13*60) = 780 watts.

Your stock '79 headlights find ALL SIX filaments (two each per low beam lamp and one per high beam lamp) burning when set to "high". This means that your running current on high beams will be less than stock. You do NOT want to turn off the HIDs when going to bright lights because when you go back to low beams there will be a noticeable, annoying and even dangerous period as you wait for the HIDs to ramp up to full output.

Regarding starting current: (I hope my explanation won't rile experts.) Incandescent lamps also draw far more current when "starting" than "running". This is call the "inrush current". While very brief (either milliseconds or microseconds) it's the time it takes for the filament to heat. If you had an extraordinarily quick reading meter connected to a stock Corvette bulb you'd see the amperage go way up while the voltage goes way down during the inrush. Everything happens so quickly that there is no problem despite the fact that the wiring, circuit breaker and switch contacts are unable to safely carry the inrush load for any length of time.

The situation is different with HIDs. To "fire up" the HID the ballast provides an extremely high voltage for a very brief time. (I'm not sure how high or how brief but it definitely does this.) If during this period the wiring/switch contacts/etc. provide too much resistance the voltage will drop below what is required for the ballast and the HIDs will fail to ignite. This is why you need you need a shorter/heavier path to power compared to stock.

My first real advice for this project is to CHECK THE FORWARD GROUNDS! They are likely is GREAT need of your OCD regarding rust!!!!! One is easy to get to--it's attached top center of the front cowling between the headlamp vacuum relays. The other is a pain--it is at the front lower-left corner of the radiator support. In addition to it being extremely difficult the radiator support ground was the most corroded of all the body grounds in my highly comparable '79.

Unless you go to an all-electric cooling system (your '79 L82 already had an auxiliary electric fan) or had some power hungry accessory like a powerful audio amp(s) there's no need for or benefit of an "upgraded" alternator. If you do install a higher output alternator it is VERY important that the wiring for the new/increased circuits are COMPLETELY separate from the stock wiring harness!!! 60A is already pushing it with regards to the stock power distribution--draw much more current and you're asking for a fire that--hopefully--is confined to the fusible links Just as with stock you new power distribution wiring should be protected by fusible link(s).

 

Thanks. I'm going to see if there's ANY way to get the wire to make it all the way back to the battery- I guess just follow the wire that already goes to the starter and then back to the battery. I think if I mount the relays near the brake booster, I might be able to get it to reach back there.... (probably wishful thinking) If not I'll go to the starter.

You missed in the diagram where the built-in fuse is. (The harness has a stand-alone fuse; if I can get it into the interior right next to the fuse box, I will but otherwise I won't bother and I'll probably just mount it next to the relays.)



A pretty common mistake, but no I wasn't making that mistake this time; I just didn't bother to take the time to convert in the post between watts and amps.

Wow! You're right. I never stopped to think about that. Very good point!

Wow! I've been looking for a simple description of where the grounds are located. I'll definitely attack both of them before powering these on. The first ground is PARTICULARLY easy to get to while I've got the headlights out of the car. I just did a bunch of rust remediation this weekend in everything from the radiator forward. It's just VERY light surface rust (except for the metal bar that connects the top of the front fiberglass bumper), but it annoys me and while I'm in there I go nuts with the stainless dremel brush and then rust inhibitor paint, followed by proper paint.

I've got a computer-controlled trans, and will have all an all electric cooling system, electric fuel pump, holley fuel injection computer, and a touch-screen stereo. -I'd like to have excess capacity for any other electric gadgets that strike my fancy, too. (Wiper conversion, electric power steering pump, headlight actuators, etc...)


I will need all the juice I can get.


Adam

 

If you go all the way back to the battery you'd better make that wire at least 10 gauge. For all practical purposes the battery lug at the starter, the output lug at the alternator and the positive connection at the battery are all the same electrical point. Running a wire all the way to the battery is a waste of time, money and wire, but it's your car and your money.

 

It's a pre-made wiring harness. The wire gauge is what it is, and it reaches where it reaches. The cost doesn't change depending upon where I connect it. It probably won't reach to the battery anyway.



Adam