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Doin' the headlight relay thing...

dremu

dremu

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Played with it a bit, and saw between half and three quarter volts more at the bulb than through the factory wiring, though some of it is a bit suspect. Pic DOESN'T show the moldy-cottage-cheese-looking goo that came out of that socket :(

Anyway, was wondering if any of y'all had done anything scientific, photos or anything, to compare the before-and-after of the relay upgrade, besides just checking voltage. I think that means about 10-15% more power at the bulb, which is cool for the low-buck nature of the project.

I'm amazed to see that LMC sells a kit for this, but they get something crazy like thirty or forty bucks for it! ... I'm cheap :D

Though I may also spring for a set of H4's for this thing, and some like 90/100 bulbs :D ... but AFTER the relay trick!

-- A

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which relay thing are you talking about? i did the quadbeam highs thing on my truck, but having that extra voltage at the bulbs would be very nice to have and i know nothing about that...
 
Oh sorry. yeah. It's generally accepted that 30-year-old small wiring and corroded connectors are bad for lighting, so new, heavier wiring is used with relays to switch... there's enough juice through the existing wiring to close the relay (err, lower current means less voltage drop, and the dropout voltage for the relay is way low anyway.) The 73-87 link is pretty good.

-- A
 
Looks like a fantastic upgrade, plan to do it in the next couple of weeks, along with an H4 upgrade (so that I can just carry a spare bulb or two, instead of a mongo sealed beam replacement). One puzzling thing is why the dual light harness from LMC would be cheaper than the single light version (check it out), when the duals kit has two more plugs and a bit more wire. I'll call them about this on Monday, before I order, in case it's a catalog misprint.
 
I've done this upgrade on all my trucks, and it does make a very noticeable difference =) Hense why I contributed to that article to help guys out :D Glad to see it's being used!

Anyways, My latest addition to the fleet, a 77 stepside truck has a set of H4s on it. And DANG, well worth the 100 bucks! Those are some of the brightest lights I've ever had the pleasure of sitting behind!

They are Bosch H4 conversion bulbs, with the european style lense on them (signified by a circled E). Running 85/65 watt drivers, and I haven't been highbeamed once. The european lenses have a far superior light pattern to them, which hugely reduces glare to oncoming drivers, esspecially with high wattage drivers (BTW, I would not run anything more than the stock H4 drivers with stock wiring, way to light of a gauge of wire, relay upgrade with heavier gauge wiring is an absolute)
 
I got hold of some cheap solar panels, I intend to measure the voltage output from them at a given range before/after the swap.

That won't give any idea of intensity we can interpret really, (unless it's a difference like between high/low beams) just an interesting way to test I thought.
 
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1985_K5_Silverado said:
Looks like a fantastic upgrade, plan to do it in the next couple of weeks, along with an H4 upgrade (so that I can just carry a spare bulb or two, instead of a mongo sealed beam replacement). One puzzling thing is why the dual light harness from LMC would be cheaper than the single light version (check it out), when the duals kit has two more plugs and a bit more wire. I'll call them about this on Monday, before I order, in case it's a catalog misprint.
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It must be a misprint for I own a 90 and it has 4 bulbs NOT two
 
dyeager535 said:
I got hold of some cheap solar panels, I intend to measure the voltage output from them at a given range before/after the swap.

That won't give any idea of intensity we can interpret really, (unless it's a difference like between high/low beams) just an interesting way to test I thought.
Click to expand...

well if anyone planing to do this knows an electrition asl them if they have a light meter.

It quite literaly measures to light output, and you could put some real numbers on this.
 
opfor2 said:
It must be a misprint for I own a 90 and it has 4 bulbs NOT two
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IIRC, in later years you could get either, depending on trim level / phase of the moon.

-- A
 
There's a site called MADelectric that goes into that also, although I don't know if he's still there. Something else I discovered while trying to get mine going. Apparently I didn't have sufficient ground. Then I put this on and now I get the full 14.2 Volts. Before it ran up and down with the revs, now its at 14 all the time. And yea everything is bright.

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question about the kits in LMC. Are the bulbs that the euro style headlight kits require something you have to get through LMC only, or do they have a part number you can pick up in stores, like a 9000 number? If so has anyone got the lenses with silverstars? I put some of those in my finacee's jeep and it made a great difference to me.
 
Yep, obviously BOTH sides of the wiring hafta be good. I did new #10's from batteries to lights on both + and - ... and checked over my engine grounds, but ya know, I should clean the ends where the bolt onto the frame and alternator.

Does this EVER end? :)

-- A
 
1985_K5_Silverado said:
Looks like a fantastic upgrade, plan to do it in the next couple of weeks, along with an H4 upgrade (so that I can just carry a spare bulb or two, instead of a mongo sealed beam replacement). One puzzling thing is why the dual light harness from LMC would be cheaper than the single light version (check it out), when the duals kit has two more plugs and a bit more wire. I'll call them about this on Monday, before I order, in case it's a catalog misprint.
Click to expand...
Well, I called LMC, and the CS type said that was indeed the right price for the dual light harness, even though it was cheaper than the simpler single version. Still slightly confused, I went ahead and ordered one of the 36-3581 dual light harnesses for my 4-headlight '85, and we'll see which one I get from the UPS guy. Only 27 bucks including shipping.

I was going to order that Hella H4 light upgrade kit, but I wasn't sure about one thing: I have four headlights, and there are two lights in the kit. What would I do about my other pair of headlights (the high beam only ones)? Do I get a second Hella kit for those and just get some 100 watt single filament bulbs for those, or what?
:confused:
 
Light output can be measured, but I don't know anybody that has the tool to measure the change. Having done this mod to my K5 I can say you will see the difference. Even before switching to the H4 conversions, the Halogen bulbs got much brighter/whiter light. Comparing my truck with Relays and halogens to my buddies truck that was stock w/ halogens was pretty difinative proof. With both trucks on low beam, mine had the light output like mine was on high beam compared to his. Both on high, mine were at a different level of brightness above his. Add the H4's and you have an even greater difference in output.

I will say this, H4's are a great addition to add brightness but to get the full potential out of the H4's you should do the relay mod at the same time. It's not hard to do. At least you will be able to see again at night...

Rob Z.
75K5 350/465/D44/12B/4"/35's
 
So, let me ge this straight. The kit from LMC will work for my 91 (4) four light system? Do I have to switch to H4's to get better lighting? Can I use my original lights and get more lumens by upgrading my wires (less ohms)? :crazy:
 
I don't know that anybody makes a H4 bulb housing to fit the small 89-91 4 bulb system. The 4 bulb LMC harness should work and get you better light output by increasing the available voltage to the lights. If you use the LMC kit, it includes all the wiring for the lights, including the ground wires, I don't remember what gauge the wiring was, but it should not be a issue. You can up grade the wiring size if you want, but it would mean you are rewiring something you just paid 30 bucks for. Might as well do it yourself with heavier wiring to begin with. Still, going from the size the LMC kit has to 2 sizes larger is not going to net more than a couple tenths of a volt more. An improvement, but not as noticible as going from stock to the relays.

Overall, the LMC kit is pretty nice for the price. Except the very poorly translated english instructions. And the fact there is NO fuse protection on the power feed circuits to the relays. The instructions are easy to work around, you just unplug the stock light bulbs, plug the male connector headlight connector into one of the stock headlight connectors, hook up your grounds and power to the relays and you are done. However, without any fuse proctection on the power ciruits (two red wires, one to each relay) you could have a serious problem on your hand if they short to ground. Meaning, the front end of the truck (if not the whole truck) could go up in smoke before you can open the hood to try to disconnect the wiring. Spend an extra $5 to buy two inline fuse holders and install them on the red wires at the point where you pull your power from. (30 amp fueses). Then if a wire shorts to ground the fuse snaps instead of setting the truck on fire.

Basic electricity, never have an unfused circuit.
 
I just searched for more info. But one post, which was excelent BTW, said to pull power from the alternator and run another cable from the alt to the battery? I figured you could just run directly from the battery for power, is this wrong?
 
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