Introduction: BIKE LIGHT 500 Lumen "Mt.Bike" for Under 10 Bucks NOW W/ LED TECHNOLOGY by Veggiecycle

Picture of BIKE LIGHT 500 Lumen "Mt.Bike" for Under 10 Bucks NOW W/ LED TECHNOLOGY by Veggiecycle

Most good rechargeable tungsten halogen Bike Lights that put off a good deal of light (200 to 600 lumen) cost a ton of money 75 to 200 bucks. I took my really expensive light apart and found that its just a bulb you can buy anywhere for $ 4.00 and some rechargeable batteries. So here is a CHEAP way to build your own with part that you can get from Home Depot (mostly) This is a no frills light. I didn't put a switch on this one. I have been adding switches to my new ones.
........................NEWS FLASH.. I have added an LED for better energy management  See the last step for LED upgrade......................................

I have another bike light

Step 1: First You Need a Body. I Found That a Trap Adapter and a PVC Female Cap From HD Plumbing Dept Works Good.

Picture of First You Need a Body. I Found That a Trap Adapter and a PVC Female Cap From HD Plumbing Dept Works Good.

Trap adapter ABS-DWV 1 1/2 x 1 1/4 $1.14
Female Cap VPVC Sch 40 1 1/4 (threaded)$.78

Step 2: I Use a MR16 Bulb Its the Kind Made for Track Lighting

Picture of I Use a MR16 Bulb Its the Kind Made for Track Lighting

Next I use a MR16 (WITH THE LENS BUILT IN) bulb its the kind made for track lighting. I use 12 volt only and I like a 10, 15, or 20 watt bulb. You can get the 20 watt from HD for 4.95 the lower watts bulbs you need to get online from a lightbulb dot com place or a specialty light bulb store in your area. You will also need a MR16 socket that you get from a specialty place for $2.00 and a Conduit Hanger and 1/4 inch thumb screw to replace the screw that comes on the hanger (to make it easy to adjust or leave the screw on and crank it down and forget about it ) and a nut and bolt to hold it to the Body

Conduit Hanger w/speed thread size #0 3/8-1/2 5pk $1.90 HD
MR16 Bulb 20 watt Aprox $5.00 HD
Thumb Screww 1/4 " 3pk $1.29 HD
Lock nut (nylon insert) #10-24 4pk $1.29 HD
Bolt 1 inch long #10-24 4pk $1.29 HD
MR16 Socket $2.00

Step 3: No Hub Coupling From the Plumbing Dept

Picture of No Hub Coupling From the Plumbing Dept

Next a No Hub Coupling from the plumbing dept to make a tight sleve to hold the light bulb in place and make it water (tight??). You are gonna pull the rubber part out and cut it in half but leaving the middle rim on one side then trim it to abot 3/4" to an inch total width. (I hope that makes sence once you start cutting it)

No Hub Coupling 1 1/2" to 1 1/2"

Step 4: Kinda Together Showing the Rubber Seal Holding the Bulb

Picture of Kinda Together Showing the Rubber Seal Holding the Bulb

We kinda jumped ahead with this pic so you could see what this was for.

Step 5: Drill a Little Hole and Tighten the Hanger on the Hub

Picture of Drill a Little Hole and Tighten the Hanger on the Hub

Just use any small nut and bolt to hold it on. I have been using wing nuts, and lock washers so I don't need any tools for this step. FLASH new pic update The wing nut and bolt and lock washers is the setup I like to use now.

Step 6: RCA Male/female

Picture of RCA Male/female

I like to use an RCA cable. Cut it about 3" from one end. Drill another small hole in the cap or body and stick the short piece through and soider it to the socket.

RCA male/female end cable $3 Radio Shack

Step 7: Battery This Is Gonna Cost You a Little Bit

Picture of Battery This Is Gonna Cost You a Little Bit

You need to find at Radio Shack or a specalty electronics supply for a 10 AA batteries holder. Solder the other end of the RCA cable to it and ....
The best battery to use is a Nickel-Metal Hydride or NiMH 2500 mAh I found the Energizer from HD the best price. You need 10 cuz they are 1.2 volts each 10x1.2 = 12 volts. Put the battery pack in your underseat bag or in a water bottle. The light should work for 3 hours with a 10 watt bulb and 10 2500 mAh batteries. Or 1 1/2 hours with a 20 watt.
If you have any questions drop me a line....

10 AAbattery holder $1.00
Energizer 4-Pack AA NiMH Rechargeable $8.97HD
Energizer 4-Pack AA NiMH Rechargeable w/charger 17.95

Step 8: Put It All Together And...

Picture of Put It All Together And...

It should work like a charm..
I got this bike water bottle battery pack that is 5 mah with the quick charger from They have tons of great batteries on that site.

Step 9: LED Is All the News. So... I Have Added a Simple LED Upgrade

Picture of LED Is All the News. So... I Have Added a Simple LED Upgrade

Everyone is running LED on their bikes now, and why shouldn't they?? LED lights are cheap, have tons of light and use a lot less power. When I posted this project in 2006 LED's were just hitting the market and cost a ton of money. The market has changed and now you can buy good LED lights for a great price.
But.... There is still the DIY factor (that's why we are all on here, right?)
Here is a simple way to build a LED bike light without having to mess with any circuitry, little parts or soldering.
I just went to my local hardware store, light bulb store or online and bought a  4 Watt LED MR-16 It is rated at 300 lumens or a 5 Watt at 500 lumens and plug it in.... POOF!!!  like magic your done!!!


TailsL (author)2017-12-17

not bad idea just use 3 or 4 cell of 18650. as power supply.

with your led.

andrea biffi (author)2012-11-21

great, I've made something very similar maybe 12 years ago, I used to cycling in the woods by night, and I had a 20watt light on the bike and a 10° 20w on the helmet, it was awesome!

Tacks (author)2012-10-20

This works great and has extended my biking hours, thanks a lot. One thing that I hadn't heard anything on and would add is that bulbs range a great amount in beam angle. The one I picked up for cheap on amazon is almost a 60 degree beam (categorized as a wide flood light), spreading 400 lumens out over a large area. I would suggest a narrower beam, since it seems that a decent amount of my light is scattered in random directions and it does me no good. I'll be ordering a 30 degree bulb relatively soon and will report back (hopefully with pictures) with the results of bulb switching.

agentcooper (author)2012-09-22

There's lots of comments already, but I just wanted to add my thanks to the long list. I put this light together today, and I am quite pleased with the results.

rustytoy (author)2012-09-21

I assume your batterys last a lot longer eh?

muddyboots (author)2006-09-16

How long do 10 AAs last on a 20 watt bulb?

Dunhausen (author)muddyboots2008-08-05

Depends on the batteries. To convert a battery's amp-hour capacity to watt-hours multiply the amp-hours by the voltage (12) and then consider what wattage of bulb you're using. For a 20 watt bulb with 2600mAh batteries you're looking at 1.56 hours theoretical run time, and twice that for a 10 watt bulb. Concerning the project: rather than drill a hole for the conduit hanger I just reused one of the hose clamps from earlier to attach the device around the narrow section of the light. it worked out very well. A bit of rubber or cloth is good to increase friction with handlebars and prevent it from sliding. You could also paint a little rubber cement in there or something. Any ideas on a trickle charger circuit for this? Just needs to output >12v and ~90 milliamps and it would be perfect to leave it plugged in at night. Kind of defeats the points to spend $30 on a charger, $20 on batteries. :p

QuikMart (author)Dunhausen2008-11-03

Mmmm... Don't be fooled by those manufacturers numbers. Those capacities are obtained at a much lesser discharge rate, more like 1/2C. At 20 watt your at (2,6/ (20/12)) 1.56 C. So you can't expect less run time. Duracell provide very good information on their website... You can aslo use a cheap Sealed Lead-Acid 12v battery wich cost 10$ and a generic charger for about 5$ - 6$...

Yard Sale Dale (author)QuikMart2011-11-23

My experience with 12v 7ah SLA batteries is that they are HEAVY (6-7 lb), and they do not like being discharged at the rate that these MR16 bulbs take! I get run times of 45min to 1 hr. Sometimes more if I stop running the light for 10 min or so between runs of 30min. Also, they fail in cold weather, which is the main time I need my light!

i made 1 of these lights but i found if you use the led replacements instead of halogen bulbs your batteries last a lot longer. run time on my light with a 50w halogen was about half an hour and with the 60 led bulb its about 4 hours

Yard Sale Dale (author)2011-11-23

Thanks for the instructable. I will keep playing around with the MR16 because I like the light frequency it puts off, and its a fun hobby. Try batteryjunction com too for your lighting hobby or just buying a complete light. They cater to cyclists, cave spelunkers, and hunters.

Yard Sale Dale (author)2011-11-23

I really like your idea of the RCA connector. That looks like a strong, low resistance connection, and should not pull apart too easily.

dlfynrdr (author)2010-06-07

Why not just use one of those rechargable battery packs they sell for use for an RC car? A lot more compact and cheaper, and still 12v.

Yard Sale Dale (author)dlfynrdr2011-11-23

You could do that too, but if any of the cells weaken or are damaged, you have to replace the whole unit. This system (aa's) would allow individual batteries to be tested and replaced more easily. Also you could use up gift or leftover AA standard batteries. Some people even recharge alkaline AA's with the new home chargers ($40) that are popularized through dpt stores.

jarrelb (author)2011-03-06

i wonder if you could use this same configuration to replace a bulb on my 50cc scooter...which is 35amps? the stock bulb is vastly weak

Yard Sale Dale (author)jarrelb2011-11-23

I ride a motor bicycle, and the 20w 12v narrow flood beams do NOT work well in traffic. this bulb is WONDERFUL for off road riding at 5-15mph though. SInce you will have a bigger battery or generator system, you may be able to get satisfactory results by using 2 of these, one with a narrow flood beam and one with a narrow spot. If you can run a 35watt bulb with your scooter, just buy a fog light or dune buggy light, probably you will be happier.

Yard Sale Dale (author)2011-11-23

That's great! I was wondering if you could get enough run time from AA's to make it worth bothering with. Look on batteryspace com for DIY light supplies and batteries. They cater to bicyclists fed up with overpriced kits. I use a "hip pack" for my current battery (6lb!) so I think 2 10 * AA's should fit in there great.

Yard Sale Dale (author)2011-11-23

Howdy. I used the same bulb and a PVC pipe reducer. The threaded part is used to cap the lens onto the part that held the bulb, and the plug is held on by a ziptie strung through 4 small holes on the base. Yours looks really good though. I like the thumbscrew idea!

jbaillargeon (author)2011-11-11

Why wouldn't it be better to use just 1 long battery holder. then using to of them. u could have that go any where on yr Bike. i would do that in stead of to or more. & i don't no y u couldn't use a Solar Powered Unit like they have at Harber Freight. people use them to keep there Battery charge up in there car. so Y can't u use that 4 yr Battery on yr Bike light

amberisdelighted (author)2011-08-06

I am very excited about this project, however I keep getting curve balls thrown at me. I bought a battery pack today, however it doesn't have the red and black wires connected to it, just a pos and neg stud. Is there anything I can do, or do I need to find another battery pack matching yours?
Also, I was advised at RadioShack that Hooking Wire would also be usable in a project like this, however without the red and black wires, I'm wondering if I've just collected a bunch of pieces that don't fit together.

Thanks so much!

Just solder the wires...

Just soder the wires....straight onto the the battery pack?

Your comment is a bit ambiguious.

I have soldered to batteries many a time, the trick is to put solder on the wire and then touch the wire to the contact while the solder is still molten. I sometimes use a flat piece of metal to press the wire to the contact as well. The result is a pretty decent connection without getting too much heat into the battery.

jgilbert5 (author)2011-11-08

I just wanted to say that I followed this instructable several years ago and this light comes out every winter when the time changes. I dust it off, throw it on the bike, occasionally change the batteries due to old age, and I'm off.

This thing is by far one of the best and most useful instructables I've found on here and I've made a bamboo bike and my own furniture!.

Thank you again for putting up this awesome tut!

DDRAMbo (author)2011-10-07

I'm wondering if at this point, and for other projects with a need for a similar battery holder, you could substitute the battery case from a laptop battery, which is essentially a battery holder for a bunch of AA-size rechargeable batteries. Dead or cheap 'used' laptop batteries should be widely available. Just a thought.

Kikkoman56 (author)2011-07-18

Hey great instructable! just letting you know DealExtreme sells MR16 size LED bulbs for similar price! They're not cheapo LED's either, an array of 4 Cree LED's for $7.70 and use more than 1/4 of the wattage =D

dlfynrdr (author)2010-12-24

If you added a plastic cover over the lens to make it more or less water resistant, would the extra heat build-up be a problem?

maethor (author)2010-11-09

Hot glue ;-)

unaffiliatedperson (author)2010-10-30

whats the run time on these lights? i plan on using a car battery i have laying around with relays. how long might that last? might also put a 100 W amp for audio.

maxwelltub (author)2010-10-10

I have used these lights in the past for other projects. They are super bright and only 3 watt so they might work better with a battery back.

zadamxtr (author)2010-04-15

Bad idea.  It would be almost impossible to find a 9v and 2 1.5v batteries that had the exact same charge capacity.  Mixing batteries of different type like that at best is a waste as your setup will only last as long as the battery with the lower capacity, and at worst will kill your batteries.

CybergothiChe (author)zadamxtr2010-09-05

why can't you just use two 9Vs?

zadamxtr (author)CybergothiChe2010-09-05

The voltage would be too high if you used them in series, and a bit on the low side if you ran them in parallel (although it would still probably work). However, 9v batteries (I assume you are referring to those small square ones?) don't hold a lot of charge, and your run time would be very short, that is the main reason you wouldn't want to go 9v batteries.

maxwelltub (author)zadamxtr2010-10-10

When your charging the batteries do you use a 12volt charger, or do you need to take the batteries out and charge them in fours.

congamongo (author)2006-10-06

Also, does it matter what mAh rating the batteries have?

Digi (author)congamongo2006-11-17

Yes it does matter on the mAh rating. To put it simple, the higher the mAh rating, the longer the battery lasts. You will notice in general, when you price shop, the higher mAh rating the higher the price.

mysss (author)Digi2010-09-02

(mAh, or milliamp-hours, are a measure of charge, so the more mAh, the longer the battery will last.) (author)2007-01-24

first im pretty sure u dont need that mainy batteries. i mean if u want threehours of battery life then yeah sure. But if u are to add a capacitor then u can have less as the capacitor will build it up to the 12 volts. an if u are using the NiMH then i think they are rechargeable (imay be wrong so dont have a go) then most rechargeables dont stay at 1.2 constantly they fluxtuate between 0.9 to 1.2, so u realy do need a capacitor. i know most lights are built to handle those etremetys but if they do they will not last as long. so back to capacitors if u have, say just a slim pack of 6 rechargeables then it may only last an hour and a half but u only need it to get home so my point is that u can then recharge them and this whole idea makes the bike a lot lighter and faster (also u can bring other backs or batterys with u).

tkjtkj (author)cheese.trading2010-08-21

I'm not sure i understand your idea, but if i do read you correctly, you are in error. A capacitor will not, can not, 'charge up' to any voltage that is higher than the applied voltage. Think of a capacitor as a 'balloon' that you try to blow-up. There is no way that you can cause the pressure ('voltage') in the balloon to exceed the pressure your lungs provide in inflating it. But perhaps you had in mind some other kind of circuit .. if so, do forgive me (but do tell me what that circuit might be.)

mobstar76 (author)cheese.trading2009-06-15

You will get get a much brighter light running at 12V instead of 6V+Cap. Capacitors are only good to hold a steady voltage on variable voltage applications such as audio amps and sensitive electronics. a light is a constant source of drain therefore there is no need.

lu1982lu (author)2010-01-13

Hi all,

I hope this is not the second post of the same thing.
I tried the circuitry, fun to make and looks great at first.  However the light emmited from my bulb is very low.  Why is that?  I tried to lift up the V to 16 AA batteries and its a little better but not much.  I use a phillips lv 12 V 20 W halogen bulb.  any ideas?

zadamxtr (author)lu1982lu2010-04-15

It's possible that the batteries you are using simply cannot output the required current to run such a high wattage bulb.  Try hook it up to a decent sealed lead acid battery, or maybe try using C or D cells instead of AA's.

The best solution is to switch the bulb to a LED one.  A 5W LED will output close to what a 20w halogen can output, but draws much less current (so your batteries may be able to cope).

zadamxtr (author)2010-04-14

Thanks for the article, I used it as a guide and inspiration to build my own night riding lights (although my project ended up quite different to yours).

Other people undertaking this project may want to consider going for high power LED MR16 replacement bulbs.  They are a fair bit more expensive (I paid around $30AU per bulb for mine) but output a lot more light per watt than a halogen.  In my setup I ended up going with a pair of 3w LED bulbs, each one outputs around the same amount of light as a 10w halogen, for only 33% the power used. 

I've set it up with a 3200 mAh sealed lead acid battery and get around 4 hours run time with both lights going, or 9.5 hours with a single light.

I've found that the twin light setup works well as I am using one bulb with a wider 40 degree beam, and one with a narrow 15 degree "spot" beam.  Gives a great result for high light and visibility both close to you and far away.

To get a similar amount of light with halogen I would have had to get a 20-30w bulb giving me a much shorter battery life.

lu1982lu (author)2010-01-13

Hi guys,
I was thrilled to see this instrucible but when I finally made it, (cost around 30 euro) It seems that the halogen light has far toolow brightness for any use, as a matter of fact a normal small one battery torch could have the same luminence I think.
What could be wrong? any ideas?
I increased the voltage to 16 AA to see if the circuitry was the reason but nothing, still low.
I use a phillips 12V 20W halogen light and another by luxtech 12V 50W .The second doesnt even light, just deems
Thanks a lot

joshtp (author)2009-09-01

i built it, but instead of using rca i just used normal cable and some metal piping substitutes the pluming. my only problem is that it simply isnt that bright. when firts testing the super simple circit.of battery,switch,bulb. it was awsome. but now its far dimmer. Any ideas?

Tonebuckets (author)2008-11-16

Thanks for this instructable! I've never done anything like this so it was fun and challenging too. I just built this light and I mounted it on my helmet. I used a small "L" bracket, drilled a hole on the bottom of the body and then used a small bolt and nut to secure it. Since I didn't really want to ruin my helmet, I used 2 zipties (pulled really tight)to secure the "L" bracket to my helmet. Works really good and stays in place. I do feel the setup is a little heavy on the helmet though, but for the price I can deal with it. My battery setup is 3 4-pack battery holders for a total of 12 batteries. More than what is needed but I couldn't find any combinations near me for 10 batteries. They fit nicely in my digital camera carry case which I just put in my back pocket. I was having problems with the battery holders heating up and then melting (like a few of the other posters)and it was driving me mad, but I finally figured it out. If this is happening to you, and you wired the battery holders properly, in a series, all you did was cross a red and a black somewhere. Most likely at your fittings on the speaker wire. The metal on the female to male fittings have to match up. I hope this makes sense. Anyway, just thought I'd share that.

profpat (author)2008-11-09

this is so far the cheapest bike light project! i do have some tracklight bulbs stored away from an old restaurant project, but i believe they are 50watts 12 volts, i might use an ups sla battery for this.. thanks.. (author)2008-10-18

I was thinking of using my 10.9 volt lithium cordless drill battery's for the power pack. Do you think that the voltage would be high enough to make a 20 watt MR 11 close to it's maximum brightness?

It will work. It will be a bit under powered. Buy a bulb at home depot and see if it works good If its to under powered. Take it back..

MrUbuntu (author)2008-09-13

Rather than using so many AA batteries. Wouldn't it be easier to buy one SLA (Sealed lead acid) battery? It would be easier to position and would offer a much longer run time.

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