Wanna build me a light?

[slackman99]

Hi all,

I'm after a new light for my bike. Currently using a couple of LED torches with bike mounts.

I'm hoping that someone on here is looking for a project and wouldn't mind helping me out.

What i'm after is:

a bright LED bike light, ideally with a decent runtime (2hrs or more). Would ideally like somewhere around the 200+ lumen area, meaning at least 2 emitters? I'm guessing that a regulated circuit pushing around 1A will be needed, but i'm a novice, so will leave that up to the maker.

I'll supply the battery myself (either 7.2v, 8.4v or 9.6v NiMh RC car battery pack). I'll leave the voltage up to the kind person who makes the light to tell me! I'm hoping that something like a 2400mAh pack will give 2hrs+ runtime.

I'll only need a single mode (on=full power, off=off)

Would like a switch attached to the light, and would ideally like the light to come with 1m of power supply wires to which I can attach my own power connector.

If anyone has built such a beast, and fancies building another, then please let me know.

I'd obviously cover costs, but would like them to be kept to a minimum please!

Cheers in advance for the help!

Dave

 

[n4zou]

Hi all,

I'm after a new light for my bike. Currently using a couple of LED torches with bike mounts.

I'm hoping that someone on here is looking for a project and wouldn't mind helping me out.

What i'm after is:

a bright LED bike light, ideally with a decent runtime (2hrs or more). Would ideally like somewhere around the 200+ lumen area, meaning at least 2 emitters? I'm guessing that a regulated circuit pushing around 1A will be needed, but i'm a novice, so will leave that up to the maker.

I'll supply the battery myself (either 7.2v, 8.4v or 9.6v NiMh RC car battery pack). I'll leave the voltage up to the kind person who makes the light to tell me! I'm hoping that something like a 2400mAh pack will give 2hrs+ runtime.

I'll only need a single mode (on=full power, off=off)

Would like a switch attached to the light, and would ideally like the light to come with 1m of power supply wires to which I can attach my own power connector.

If anyone has built such a beast, and fancies building another, then please let me know.

I'd obviously cover costs, but would like them to be kept to a minimum please!

Cheers in advance for the help!

Dave

I've found a single 1-watt Luxeon star with matching Fraen Elliptical Beam Lens With Holder works fine for me. I put it in a 1-inch PVC pipe coupler.

The LED and optics can be purchased here.
http://www.luxeonstar.com/index.php
It's not the brightest LED light but it only draws 380mA including a bright red 5000 MCD taillight drawing 30mA. The elliptical beam pattern is optimal for road or MUP use. My battery pack is a modified R/C 9.6-volt Ni-MH battery pack purchased for $5 on clearance sale. I cut it open and spilt the 8-cells into 2 paralleled 4-cell packs for 2 4.8-volt X 2.4 amp hour capacities. I ride at night a lot so I also added a dynamo so I could recharge the pack while running the lights. I never need to plug in the batteries. My lights also stay on when stopped or riding in very slow traffic (below 8 MPH). The batteries also regulate the voltage and excess current produced by the dynamo when riding above 8-MPH. The excess current simply recharges the batteries. This also allows using resistors to set the current for the LED's instead of a current regulating chip like the AMC1735. I am mostly on an MUP so occasionally I need to disengage the dynamo and run on just the batteries so I don't overcharge them. I typically run on batteries for 15 minutes and engage the dynamo for 45 minutes keeps the batteries toped off without overcharging them. Here is the circuit I use.

Switch S2 is used with hub dynamos and not required with bottle dynamos.
The 4.9-ohm resistor is a combination of resistors found by adding resistors until 350mA is read on a milliamp meter connected to the 1-watt LED with the battery pack fully charged. My resistor is a 5-ohm resistor with 3 50-ohm resistors paralleled to obtain just under 350mA. I started with 5-ohms with a current reading less than 350mA and then just started adding 50-ohm resistors. Here is a photo of the test setup showing switch S1, diode terminal board, and another terminal board making adding or removing resistor combinations and connecting meters for testing.

Everything can be put in a small plastic project box after your satisfied with your setup.

 

[diff_lock2]

I say screw Luxeon. Get a seoul that puts out like 100lumens at 350ma.

Also... do you really see with that 1w luxeon? I have a 3w luxeon with a 25deg lens and i cant see jack. i ordered a 6deg lens to compare.

 

[Illum]

simplest method would be buying two flashlights, one built for throw and the other built for spot, then connect two hose strainers into an 8 shape, one ring for the handle the other for the light [use inner tube from a old tire to increase grip on the light and minimize scratches].
pick a empty road and night and make your alignments for flood and spot. your done, w00t!

if your looking for longer runtimes, do a little user modding on the chosen lights by creating a dummy battery contact with hookup wires and wire them to a simple switch assembly and some NIMH battery holders both available in radioshack

possibilities are infinite up to this point, on a clear night out you really don't need all that light. I know because I once biked 2 miles on a previously unknown road with no streetlights with only a photon II. good thing it was paved though

 

[alexlockhart]

I'm in the process of building my own light, and if I weren't in a time crunch, I might build one for you. But having just done a bunch of research, I'll throw my thoughts in.

a bright LED bike light, ideally with a decent runtime (2hrs or more). Would ideally like somewhere around the 200+ lumen area, meaning at least 2 emitters? I'm guessing that a regulated circuit pushing around 1A will be needed, but i'm a novice, so will leave that up to the maker.

A single Cree or Seoul can output 200+ lumens at 1A current, but it's more efficient to use 2 and drive them at 500mA each or something, and more efficient yet to use 3 and drive them at 300mA each, or drive them at 500mA and get 400+ lumens.

In my opinion, what's more important than the amount of light is the beam pattern. That's determined by your primary use - will this be for the road or for MTB? Assuming it's bar-mounted (not helmet-mounted), a good beam for the road is an elliptical beam to see the road in front and to the sides, coupled with a spot beam to see the road further away. A flood beam wastes a lot of light up high and down low where there's nothing to see, and also annoys oncoming traffic more than properly-aimed elliptical and spot beams. For MTB, a spot and flood combo works well, since there is often stuff to see up high, and you're not worried about annoying oncoming traffic. Also, most people find that they need more light for MTB than for road riding, since it's a lot more important to see the terrain, and there's rarely any significant ambient light (from streetlights, etc).

I'll supply the battery myself (either 7.2v, 8.4v or 9.6v NiMh RC car battery pack). I'll leave the voltage up to the kind person who makes the light to tell me! I'm hoping that something like a 2400mAh pack will give 2hrs+ runtime.

For a 200+ lumen light, a 2-Cree/Seoul setup at 500mA each is ideal, since you can have good efficiency and good beam pattern. That's about 3.8W power draw including driver losses. A 7.2V, 2400mAh pack has 17Wh, which would run that light for over 4 hours. If you ran 3 LEDs at 500mA each, you'd have 400+ lumens, and consume almost 5.5W, and if you used a 9.6V, 2400mAh pack (23Wh) with that light, it would still last 4 hours. Obviously, your goals are set low - you can expect twice the lumen output you're aiming for, with twice the runtime you're aiming for, or some balance further towards brightness or runtime.

Just wanted to throw those ideas in there. Besides a cost savings, the other main benefit of DIY lights is the custom design - there are a lot more options available in the DIY world than the commercial light world. So even though you're asking someone else to make some decisions for you, you'll need to specify the light's primary use and desired beam pattern, and you should also specify what kind of mounting options are acceptable - i.e. bar-mount, helmet-mount, quick-release, etc. And if I were building the light for you, I'd have to ask for some "service fee" or something like a markup to at least partly cover my time as well as the actual material costs. That's up to the generosity of whoever builds it, though.

Alex

 

[slackman99]

Many thanks for the help. I've decided to have a bash at building the light myself.

I've ordered 2 3w Cree drop in units (both with simple regulation) which i'm going to fashion into lights.

I'm going to make housings for them, and drive them off of a 7.2v rc pack, or possibly two (one each). The drop ins are rated at 3.6-9v input, so should handle a 7.2v pack directly into them. I'm a little worried that a series connection might not have enough juice to run them?

I've heard that drop-ins, or their regulators don't like being wired in series, so I was tempted to wire in parallel. This also gives me the option to as individual switches into the equation so I can use one light or two.

Can anyone comment on the effects of wiring either parallel (receive same voltage?) or series (receive same current?)

The units drive a Cree P4 as 900mAh, which is obviously more than the calcs above assume for runtime of lux. I'm guessing I should be able to get a decent amount of light out of them.

The lights will be used for some gentle off road riding (nothing too technical as i'm not that good even in daylight).

I concocted a simple handlebar/helmet mount light last night out of a two AA led flashlight. Basically took the body off, soldered a wire to the +ve connection, and one to the head of the light, and ran them to a AA battery holder. Thing that confuses me is that 2AA ran the light, but now it needs a 4AA battery holder to get it to light (with a 3 AA holder the light doesn't light). That doesn't bother me if i'll get additional runtime, but it has confused me as to why, as I thought the battery holder was series.

 

[n4zou]

I say screw Luxeon. Get a seoul that puts out like 100lumens at 350ma.

Also... do you really see with that 1w luxeon? I have a 3w luxeon with a 25deg lens and i cant see jack. i ordered a 6deg lens to compare.

I see just fine with it. It's much brighter than the 2.4-watt bulb and dynamo headlight that came in the dynamo lighting kit.
The trick is the elliptical beam pattern like that used by motor vehicle headlights. You're wasting over half your light by using simple "flashlight" circular beam patterns.

 

[n4zou]

In my opinion, what's more important than the amount of light is the beam pattern. That's determined by your primary use - will this be for the road or for MTB? Assuming it's bar-mounted (not helmet-mounted), a good beam for the road is an elliptical beam to see the road in front and to the sides, coupled with a spot beam to see the road further away. A flood beam wastes a lot of light up high and down low where there's nothing to see, and also annoys oncoming traffic more than properly-aimed elliptical and spot beams.

+1
I've had brighter lights but I ride so many hours in the dark I found myself depleting my batteries at the worst time. With my elliptical beam pattern optics and matching 1-watt LED I get by fine with the available light and instead of being worried about depleting my batteries I must be careful not to overcharge them! that's a problem I can live with.:twothumbs

 

[alexlockhart]

Congratulations on deciding to do your own work! Even for a novice (perhaps especially for a novice) it's very satisfying to get good use out of something you built yourself.

About series/parallel wiring: When you use a single driver to power a string of lights in series, that driver needs to be able to supply the voltage of all the LEDs added up - usually about 3.7V each for Crees, and it regulates the current flowing through them, with each getting the full current. Most drivers are buck regulators, meaning they output lower voltages than you input, so if you have 2 or 3 LEDs wired in series from one driver, you add their voltages, then add 1-2V for the regulator, and that's your minimum required voltage to make it work. If you wire 2 LEDs in parallel from a driver, you will only need the driver to supply the voltage necessary for one of them, but they will each only get half the current that the regulator is outputting.

What you're doing, though, is different from what the majority of multi-LED setups have - you have one driver for each LED. That's fine; since you have cheap drivers that can only run one LED each, that's what's necessary to use multiple LEDs with them. They can accept input voltages of 3.6-9V, which means they are buck regulators, and that 3.6V number is probably not actually enough to drive the LEDs at the full 900mA. If you wire the regulators in series from the battery pack, they will each see half the voltage of the pack, meaning 3.6V each when the pack is fresh, and less when it's not. If you wire them in parallel from the pack, they will each see the pack voltage, which is right in their range, and thus the recommended method. Regardless of the wiring method, though, they will each drive their respective LEDs at 900mA if they get enough voltage. And also regardless of the wiring method, they will put the same drain on the battery.

For off-road riding, you should try to find 2 round lenses; one "spot" meaning 8-12 degrees beam angle, and one "flood" meaning 14-20 degrees. This will make a nice combination to see the trail right in front of you, the branches to the sides and above, and the trail ahead of you.

At 900mA, the lights and regulators will draw about 3.7W each, 7.4W total, so if your 7.2V battery pack is 2400mAh, it'll run them both for 2+ hours. You'll be getting about 400 lumens, which, if you have a good useful beam pattern, should be more than enough light.

Do you have a multimeter? If you don't, you should. If you do, you can figure out your puzzle with the 2AA flashlight you mentioned. Just measure the voltages at the flashlight head when using 2AA and when using 4AA, and if you can, put it back how it was with the 2AA originally and measure the voltage at the flashlight head. You should be seeing some numbers that solve your problem - I could make some speculations but your multimeter will tell you more.

Alex

 

[diff_lock2]

I think you guys are absolutely right about the flood beams. I think its time i try an 6x25deg beam (luxeon led). And a 12deg spot for my halogen setup.

 

[rooster cockburn]

Could try one of these.

http://cgi.ebay.co.uk/New-Halogen-B...ryZ22689QQssPageNameZWDVWQQrdZ1QQcmdZViewItem