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My "testing" of the headlight relay conversion

Discussion in 'The Garage' started by dyeager535, Feb 6, 2007.

  1. dyeager535

    dyeager535 1 ton status Premium Member

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    I never had much doubt that our headlight circuits are hurting and that the headlight relay conversion will of course help.

    However, I thought it might be nice to test the setup before/after and one other way. I have some solar cells, so I thought it might be cool to see a before/after using them.

    Well, solar was actually the easiest to test, so I did. Placed a small solar cell 30" from the single high beam (quad headlight setup, mid 80's) fixed to the garage door (truck parked/off) measured voltage generated by the cell with the flashlight on it, (.45V) then with straight battery voltage (11.72V, it's been sitting for awhile) to the headlight (.55V) and finally with the stock headlight wiring. (.55V) I may have to play around with the cell some more, I don't believe it's "maxed out" on voltage output though, maybe I'm too close, although that shouldn't be a factor. Stronger light, higher voltage output. Close=more concentrated beam/strong light.

    I next checked voltage at the headlight plug, stock switch wiring. From the 11.72 system voltage, it was down to 10V even. That was even using a separate ground. The headlight plugs I grabbed from the 'yard to do these tests were in bad shape, corroded, so I hit them with a wire wheel before tests. Not sure how I'm going to do it, but I need to pull the stock headlight wiring and clean the contacts to give it a fair shake. But almost 2V in a 12V system is obviously huge.

    Right after I get done installing the fuel filter clamp, heated O2 sensor, new injectors, and burning another PROM, I'll get to cleaning the contacts and finishing this "test". Or I'll get bored of the above 4 at some point and switch gears and finish the test sooner. :)

    What can I say, I like testing stuff.
     
  2. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    I noticed a substantial increase from the relay mod... 10 gauge short feeds right to the lights, effective.... I would guess about 15% increase, even from my crappy original bulbs... Obviously, just a guess tho..

    Now I need to sort thru all this bulb mumbo jumbo to find the best replacement bulbs... I don't wanna have to mod the buckets or any bull like that... I don't mind a replacable rear bulb.. Don't know if that means H4 replacements or something.. E-code or whatever I gleemed from that other thread...

    I seem to remember hearing for a stock replacement bulb, the Sylvania silverstars where good... Not a pressing issue, but I do need to research it at some point...
     
  3. kp texan

    kp texan 1/2 ton status

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    When I did my headlight upgrade (see this thread: http://coloradok5.com/forums/showthread.php?t=175548), I can't remember the exact change in voltage with the relays, new wiring, and new connectors but I do know that it was huge when I measured it. There is quite a voltage drop when the power has to travel all the way from the battery, through the stock headlight switch, back through the crappy stock corroded small gauge wiring, and then to the corroded stock connectors.

    -Wes
     
  4. ZooMad75

    ZooMad75 1/2 ton status Premium Member GMOTM Winner

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    When I did the relay mod on my 75 I measured the voltage at the bulb sockets and noticed a significant drop in voltage with the stock setup. I did my tests with the engine running at idle so system voltage was in the 14.5v area. I was easily dropping a full volt by the time the power got to the lights with the stock stuff. With relays installed, I was only dropping .3 of a volt.

    14v to the lights is a hell of a lot different than 12-10 if you are testing without the engine running, discharging the battery than 14v with the engine running and alternator charging.

    I'd do your testing with the engine running. Your not running down the road with the engine off at night, so why should you test the light output with out it on.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    That is true regarding driving habits, but the way I'm doing it eliminates a few variables, vehicle movement (for the solar cell) varying idle, varying output voltage from the alternator, etc. I suspect if I hooked a voltmeter up to the battery while it was running, I'm fairly certain it would stay within a few tenths of a volt, but even tenths with 12V is fairly significant.

    Oh yeah, and I was in the process of changing the injectors when I decided to do this, so the truck doesn't run anyways. :)
     

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