HID Light kit for car - used on work bench

Discussion in 'General Electronics Chat' started by Tonyr1084, May 30, 2016.

  1. Tonyr1084

    Thread Starter Well-Known Member

    Sep 24, 2015
    Problem: It lights when powered from a 12 volt 5 aH battery but doesn't light from a 13.8 volt 19 amp power supply. I can light it from the battery, turn on the PS and it continues to burn. But when I disconnect from the battery the HID goes out. All the while a small auto bulb continues to burn running purely off the PS. Voltage remains 13.8 volts. And I've tried two different ballasts - all do the same thing.

    The HID Ballast is rated at 55 watt; 9 - 16 volt; 8 amp (I-max).

    I want to use it in a spring arm lamp (with magnifying glass) that was originally designed for a 60 W 120 VAC bulb. I haven't any. I have a 6000K 1100 Lumen LED but it's too heavy for the springs, and it's size puts all the light in one corner. IF I use the HID I can position it in the best place to cast its light over the work surface with - I don't know how many Lumens, but it's a lot brighter than the LED.

    I've used my O-Scope to see if there's a ripple in the supply line but even at 2 V per division and a sweep rate of 0.2 µS (highest speed) I don't see any sign of ripple. The voltage remains constant at 13.8 volts, so it's not going way over the rating of the ballast.

    I'm at a loss to understand why(not).

    I'm starting to wonder if there's a start-up current that my supply can't match. NONE of my 12 volt supplies can deliver the start-up blow. Do you think that may be the problem? But here's the confusion: AFTER starting it up using the battery, disconnecting the battery and running purely off the supply it immediately goes out.

    ANYONE wanna hazard a guess? I'm open to anything right now.
    Last edited: May 30, 2016
  2. bwilliams60

    Well-Known Member

    Nov 18, 2012
    Hey Tonyr1084,
    Those HID headlamps generally fire up on 20-25,000 volts. Once they have lit, they maintain at around 85 V. I can't see a power supply providing enough power to perform that feat.
  3. Tonyr1084

    Thread Starter Well-Known Member

    Sep 24, 2015
    Hey B.

    It's my understanding the bulb itself runs on 35000 volts. But that's neither here nor there. The ballast is powered from an automotive power source, aka car battery and/or alternator. If I've been mis-understood, I'm not trying to directly light the light with 12 volts, it's the ballast that takes that 12 volts and turns it into that high voltage needed to power the High Intensity Discharge light bulb.

    I have a ring lamp that isn't very good at lighting up without having to hold the start button for several seconds. I'd love to just "Turn it on" and let everything else do its job as far as starting up the ring lamp. This weekend while on vacation in Ely Nevada (great railroad ride - not much else) a True Value store was closing. Everything was 50 to 70% off. I picked up this smaller lighted magnifier lamp for just a few bucks. But it takes a 60 watt incandescent bulb and not much room for anything else. It's light weight, so stuffing a CFL or LED bulb in there drags it down and the springs do nothing to compensate for the added weight. Tossing an old HID bulb in there would require a little bit of fabrication but when done and working, switch it on and it provides (at 6000K) perfect light for reading resistor values - something I have some difficulty with because of Partial True Color Perception (color blindness). Yes, I do see colors, but not well. Red/Green Deficient means red and green look very similar. Without sufficient light I can hardly tell the difference. But in full direct sunlight the subtle (to me) differences stand out. I also have a difficult time distinguishing between blue and purple. And to think I made a good living as an inspector - inspecting circuit boards - colors included. (great invention - the stereo zoom scope) (and Halogen reflector bulbs) (and no - I don't have a stereo scope of my own)

    I don't know why the ballast fires off with the battery but not the power supply. At best, the supply can cause the bulb to flicker a few times at start up but then it quits. A different supply will maintain that flicker, but I'm sure that's not good for the ballast. I wonder how much start up current those things draw. It's marked 8A I-Max; so I assume (yes, I know what that means) but I assume it means it draws a max current of 8 amps maximum. Perhaps its time for a measurement using my clamp meter.

    Does anyone know a way to use a 100 amp shunt for an O-Scope? I'd like to SEE the current draw at startup.
  4. Roderick Young


    Feb 22, 2015
    If you have an oscilloscope, you may be able to simply monitor the voltage on the small lead-acid battery, and from the dip in that, infer what the current was through an estimate of the battery's internal resistance.

    Maybe the thing needs 80A at a 10% duty cycle? I don't know. If the frequency is high enough, you might be able to cure the problem with a big electrolytic capacitor placed across the input.
  5. gerty

    AAC Fanatic!

    Aug 30, 2007
    At 19 amps I'm guessing the power supply is a switcher, possibly your ballasts don't like the frequency. With the battery attached it acts as a filter. I'd try another power supply, linear if possible, maybe with some capacitor filters and see what happens.
  6. Tonyr1084

    Thread Starter Well-Known Member

    Sep 24, 2015

    There's already a BAC (Big Arse Capacitor) across the input. It's there to filter out the noise found on most car DC systems. Noise causes the lights to flicker. The BAC is designed to filter out the noise and keep the lamps from flickering.

    @Roderick Young:

    I have a 40 amp battery charger in the garage. All I need is a RRBAC (REALLY REALLY BIG ARSE CAPACITOR) to filter it. Maybe I'll grab one of those high voltage transformers I scrapped from a microwave oven (with the high voltage coil removed) and wind my own 13 volt Peak transformer. Throw some humongous capacitor on it along with some 60 amp diodes I have from an old DC Welder and see what I can make.