DIY HID Ballast

HID lights have a major power consumption and lumen output advantage over halogen lights. Unfortunately the ballast component isn’t very cheap. [brian]’s been building his own ballasts for his mountain bike. We couldn’t find any more info on his design, but we did find some interesting stuff. This document lays out the requirements for a ballast. Here’s an older HID ballast design to get rolling. Keep in mind that the lamp requires high voltages – don’t play with it unless you know what you’re doing. If you’d rather use off the shelf components, check out the HID dive light we wrote up a while back. It uses a fairly inexpensive ballast/lamp combo.

16 thoughts on “DIY HID Ballast

  1. I’ve got great respect for those good enough to create their own circuits for something like this, but my own hacking tastes run toward re-use. Given that, wouldn’t a great source for projects like a mountain bike HID light be an auto salvage yard? There have to be ballasts out there which could be removed and re-used from junked autos fairly cheaply, and wouldn’t these be ideal in terms of being tightly packaged and highly durable?

    1. I work at an autowrecking yard. Yes you are correct, there are alot of vehicles that use HID lights. The high end vehicles, like Mercedes, jaguar and range Rover All have these small HID ballast that would be ideal for use on something like a bike. Most of the newer euro cars have HID headlights stock, all you would have to do is find them behind the headlight assembly, figure out what components that system and remove them in their entirety. Usually I can figure on at least two pieces, a ballast and a bulb. Some ballast like the Mercedes Benz bulbs have the ballast attached to the bulb. It cannot be removed that easily. Others have the bulb and it’s part of a modular system that makes it able pull only the bulb and leave the rest behind, anyhow, just thought I’d pass that info to you. Have a nice day

  2. @Andrew Pollack,

    I don’t know about your area. But where I live, there are just a bunch of old junkers around that wouldn’t have a HID light package.

    The only way you would get lucky is if you found a street racers smashed in vehicle, and then most likely the front end would be so damaged, the ballasts would most likely be toast.

  3. #3:

    Yes, there are… And you can expect to pay a lot for them. They’re in high demand as replacement parts for cars that have been in accidents. Since factory replacements can run thousands of dollars, auto recyclers can price them very high.

  4. Note: HID headlights on street vehicles are illegal in every state. No exceptions.

    And half of the “blue” headlights you see are just that, blue-tinted headlights.

  5. @5: You also have to be careful because most automotive HID ballasts are designed to shut down permanently when they detect an accident impact. This is to prevent the high voltage from posing a hazard to rescue workers.

    @6: Some vehicles come with factory HIDs. Those are legal. Most aftermarket retrofit kits don’t have a proper beam pattern and are illegal, though. And blue-tinted lights are illegal in every state.

  6. possibly the best idea here would be to use a little trick I picked up from which is to obtain 10 or so CCFL driver boards intended for case modding, and add external diodes and resistive grounding to stabilise the outputs. This might just work as the output power of these when paralleled is considerable and they drop to near 50V on load without damage to drive a tube, see “high voltage sparkler” :)

    I did look into Charlieplexing a bunch of smaller transformers from a broken flat screen monitor (rewind primaries as a single inline primary and then drive with a half bridge of MOSFETs) and will report back on this when I have time. Thanks!

    1. How cheap is cheap. Which bulbs do you want. As I said, I work at a autowrecking yard, I can get them if you give me a.list if which one, (color or the bulb) and how much you want to spend. If thingsatch up, I’ll send you some.
      Have a nice day

  7. Just FYI, HID’s are NOT illegal, there are several HID retrofit kits awaiting DOT approval. They are legal for off-road use, ONLY, as are most of the fake blue bulbs you see on the market.

    Having driven all over the country with my retrofit kits installed, and talking to start patrol officers in several states, no one is ever going to actually issue a ticket to someone with a HID retrofit, provided the beams are focused properly. There are numerous kits that are in awaiting DOT approval. Many new kits use bulbs that are the exact same dimensions as the OEM bulb they replace, and have the light elements in exactly the same position relative to the reflectors in the OEM housings.

    In my 2006 Jeep Liberty, the beams actually provide LESS glare to oncoming drivers than the Sylyania 9007LL bulbs they replaced.

  8. So you are saying that the stock HID headlights on my Acura are illegal? or are they only illegal when not focused properly?

    I have never been pulled or ticketed (Florida) and this is the first I have heard they are illegal in ALL states.

    Do you have background info like a link to state laws or news coverage instead of giving a blanket statement like that?

  9. NEMA has standards sheets for current/voltage delivery to different HID lamp types available for free download. I considered designing a SS ballast a while back but gave it up for greener pastures.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.