Home Made HID (front) LED (back)  Bicycle Light

This pages explains how to construct home made bicycle HID light

Philosophy behind this design:

I am using my bicycle to commute to work throughout a year. I tried different lighting systems and I come to conclusion that bike deserves as good or better lighting then average motorized vehicle. I think average biker does not make enough effort to make his/her bike visible to other motorists. Would you put LED flashing light on your car? Would you put tiny three LED white light on a truck. It would be laughable. So why put these on your bike. The technology is there to make us in par with other users of the road, so why not to use it. This article presents design that I had been using since 2005. In 2007 I changed my old NiMh 2 Kg 10AH battery to lighter 600g 8AH LIPO battery. So the battery part is somehow unproven yet. The HID lighting in the 35W versions offers the best effectiveness close to 80 Lumens/W. This is much better than average LED, for example 5W Luxeon at 120 Lumens gives only 25 Lumens/W.

NOTE: If you attempt to implement this design, please take care of carefully adjust your light beam not to blind the other drivers. Angry or blind driver could be deadly for you! The best is to use commercial car light enclosures and carefully position the HID bulb to match the original bulb position and the original light beam pattern.


Part List:

1) HID ballast - $40 shipped from eBay  store HIDconversionkit 

NOTE: HID ballast generates very high voltage up to thousands of volts. It is high enough to cause you serious harm if not handled properly. Be sure that you know what you are doing! 


2) HID Bulb - H3 6K $20.00 shipped from eBay store HIDconversionkit





3) The Light Enclosure, in Canada you can get one from Canadian Tire "Halogen Chrome Lamp Set" Product #20-3594-0 $34.99 (choose the one with white lens).

The kit contains two enclosures, use only one. You may have drill at the back of the enclosure to fit the HID bulb.

It is the best to use enclosure design for cars to assure the correct shape of the light beam. Make sure that when you mount the HID bulb, the placement of the arc is where the filament of the halogen bulb used to be. 

I fixed the bulb with 4 metal screws.


4) Li-Polymer Battery 11.1v 4000Mah x 2 - $25 shipped each - $50.00  (eBay).

NOTE: Li-Polymer can cause fire (see this or this or this video) if not handled properly. Make sure that you research proper handling of such battery. 

I used water bottle as a container for batteries. 

Do not connect these two batteries permanently together. Connect them together only when connected to the light. This prevents the batteries to cross-charge each other.

These batteries have two connectors - one big one to connect to the light and one small one to connect to the charger. The charger charges each cell separately.

NOTE: When buying battery consider the fact that at the end of life of LIPO battery the capacity will drop to 70%. As well you should leave yourself another 30% safety margin, so you do not drain the battery to the end (which is not so healthy for LIPO batteries). So if you plan for 1 hour ride between charging, assuming that the system draws 5A, you should consider battery with capacity of 10Ah. At the end of life it will drop to 7Ah, and that will give you 2Ah safety margin.

5) Charger: 2-3 cells Balance Lipo Battery Esky mini charger x 2 - $10 each - $20 (eBay)




6) Deans Ultra T plug connector for RC models x5 - $5 shipped (eBay)




7) 12V RED LED, 4 inch ROUND STOP TURN TAIL LIGHTS - $40 shipped (eBay). Make sure that you get them with connectors. I used only one of these lights. I mounted them under saddle using seat post clamp.




8) 12V 1A Switching Power Supply x2 - $5 each  - $10 shipped from this eBay store: securitystar . Used for the battery charger.




9) 5A Switch, some wires - $10 (Radio Shack)

10) Some mounting brackets, screws.


Total $220.

Luminosity of the HID Light is approx. 2800 lumens. This is better than any commercial light available.

The system draws approx 5A current. With the 2x4AH = 8AH battery will last for over 1 hour ride. You have to make sure that you do not draw the battery to the end, since this can destroy the battery. 



You can leave comments for this page here: http://bicyclehidlight.blogspot.com/

 Here are some pictures of my lighting system:

Front HID Light

Back LED Light

Charging LIPO Baterry


Bicycle lighting on Wikipedia

Patrick Limpens from Nederlands page on his home made Xenon bicycle headlight


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