7000 Max Lumen Bike Light

There are bike lights, and then there are bike LIGHTS.  My rides are mostly urban and I can get by with a lower level light because of all of the ambient light I have access to.  Reader Jesse on the other hand wanted to bike in conditions devoid of ambient light and he came up with a bad ass DIY solution.  Take it away Jesse . . .

* * * * * * * ** * * * * *

This hack is for those that like night riding or want to get into it (it's great, never too many people and nice and cool) but think that those 300 lumen lights just don't cut it and don't have the cash for a 1000-2000 lumen lighting system (they can be like $500 - $1,000 dollars, yikes). Even with 1000 lumens, it's just not enough plus some of those systems out there can only last about 2 hours at max power.

There is hope though, with this slightly overdone bike light I built for my mountain bike.

The light you see featured in these pictures I made myself and it has a max of 7,000 lumens on high with a battery life of 2.5 hours, while it can do 3000 lumen's on low power for over 6 hours.

The light is made of 6 cree xml u2 LEDs mounted to a copper and aluminum heat-sink to keep its 60 watts nicely dissipated. To power this light I built a 150 watt-hours lithium polymer battery pack all in-closed in a extruded aluminum case.

I built the case so it can easily attach to any standard water battle cage (you can see on my bike the water bottle cage just happens to be on the bottom of the frame, that's just how GT decided to do there full suspensions those years). The weight of the light and the battery and all the wires come out to just under 3.5 pounds (with the battery being the fatty at 2.9 pounds).  I also hooked up a few other cool things like rear red lights and a power level indicator so you know when you have to charge it.

The charging is done with a lithium polymer balance charger for rc cars and helis that I bought just for the light (cost me 30 bucks on ebay). I ended up building the whole thing for about $150 (would only have been $100 if i would have built a battery pack half the size).



For those who know high power LEDs have to be run at constant voltage and current to make them last (these are guaranteed to last 50,000 hours). So I have 3 parallel dc-dc converters with a 93 percent efficiency regulating them to put out 20 watts, 40 watts or full power of 60 watts to make just over 7000 lumen's of light, but the lenses I used are 92 percent efficient and I am getting about 6600 usable lumens.

To put this in comparison a standard headlight of a car gives 1000lm while a D2S Xenon metal halide arc head light you can buy gives you about 3000lm (so double that and that is what I hit the trails with). I can't imagine much more power being useful or very easily created (running this amount of power gives you a problem with heat dissipation which made me do a lot of testing to get a good rough design) but I think I will keep trying.  Next I am thinking to go over 9000 lumens (for those dragon ball Z fans out there).

Comments

[Ruben]

Could you post a highly detailed instruction and shopping list? And maybe instructions for building something with less than 7000?

I can build stuff, but I don't understand where to start with the electrical.

[Craig Domingue]

I would also like more info on this, especially the power pack and the building of the light/heatsink.

[Jesse]

Yeah i can work on a detailed instrustions and a parts list as soon as im done with finals for this quarter. I got most of the parts from ebay with few things I had layign around. If you want a smaller light it becomes much easier. I built a 2000 and 3000 lumen for my road. I give instructions for that unless anyone wants help building a bigger one

[JJ]

I'd love a write up for how to make the rear lights, I've always wanted something like that for my road bike. I don't trust drivers.

[Joyce]

That is a great light!

Riding in the city I still feel like I need a very bright light, and often wish my bright $$$ LED lights were even brighter. In fact, I think I'm going to try to build a helmet light next winter to complement my handlebar light. Deep craters and road seams sneak up on riders and before they know it, they're flying over their handlebars at 20mph. Furthermore, motorists here have a lot of bright visual clutter to deal with at night, and I think a very bright light helps approaching and oncoming drivers recognize me as a moving vehicle during their saccades, and not something static and in the background.

Thanks for posting the pony bike earlier this month. :)