Ultimate 18v Bike Light!




Mountain Biking at night (or early morning) is a true blast.. Using headlamps has been the only real choice short of spending some coin on a true bike light (some of these puppies cost >$500!!).

While the lack of light never stopped us from riding, the glory of having a MEAN bike light was calling me out.

The main problem I found with all the bike lights out there to build was the battery and housing.

  • Recharge battery packs cost some money and having another charger in the house was something I didn't want.
  • Housing is always an issue with DIY projects. I think 95% of my dads circuit boards lived in little blue hobby boxes. Sure they worked but didn't look so hot. I didn't want my new bike light sitting in a big ball of black tape.

The solution was to use the housing I found from the instructable: BIKE LIGHT 500 Lumen "Mt.Bike" for under 10 bucks by Veggiecycle -

This gave me a pretty good looking and durable housing but what about the batteries? The answer was already sitting in my charger!

1 18v Ryobi Battery Pack


I had already bitten off on the 18v series. My collection consists of the drill, saw, dust-buster, chainsaw (yup) and light.

This light is the one that we'll be using to create our 18v monster.

QUESTION - Why not just use the light that came with it? My friend tried this and it turns out that while the 18v light does give off OK lighting (and lasts awhile) it doesn't even come close to what we are building here. When you're doing you'll see what I mean.

WARNING - please please be aware that the bulb we are using here is a 12v NOT an 18v which means we are pushing (beyond) the limits of this bulb. This is a risk from a heat+safety standpoint. You can reduce the volts using various methods (one that I'm exploring right now) but in this project we push the 18v straight to the bulb.

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Step 1: Shopping List

Here are the items you'll need to build your light.

HomeDepot Purchases:
  • PVC Trap adapter 1 1/2 x 1 1/4
  • Female Cap VPVC Sch 40 1 1/4 (threaded)
  • No Hub Coupling 1 1/2" to 1 1/2"
  • Switch - 3A+ SPST (Single Pole Single Throw)
  • 12v 20w Halogen Light
  • Conduit Hanger 1/2 inch to 1 inch (size depends on the thickness of your handlebars)
  • Ballcock Shank Rubber Washer (used as a cushion between the light and hanger)
  • MR16 Socket (bulb {2} pins plug in to) - (some HomeDepots have this; mine did not so look below for links or google it)

Other Items Needed:
  • Ryobi 18v Light, Battery and Charger
  • Water Bottle (plastic)
  • Black Tape
  • Soldering Iron
  • Wire - min of 16 guage (3amp+).

  • I used a chopped up extension cord for my wiring. It can handle the amps, has 3 wires (we only need 2) and has a protective sheathing around it (this protects my wires during my many falls)
  • The socket that I bought online came with no wires but had some quick/push-in sockets. The pictures I show are off of EBAY and show the ones that have the wires. Either will work.
  • You can def use a smaller pipe clamp around the light and hanger. The one I show turned out to be HUGE.
  • If you do get a larger hanger for your handlebars, you might have to insert some foam (like we did) or rubber to get it to be tight around the handlebars.

Where to get a socket for the bulb:
MR16/MR11 Socket - GX5.3/G40 Universal Ceramic 2-Pin base GX5.3 or GU5.3 / G40 oval pin slots fits all of our MR16 and MR11 bulbs Your power wires plug and lock into holes in the bottom of the socket - $ 1.95

Info about Wire and Sizing:
Wire Gauge Tables

Step 2: Taking Apart the Ryobi Light

Let's take apart the Ryobi light and save the housing and wiring assembly/socket

  • Remove the battery from the light
  • Remove the @6 screws to separate the handle
  • Gently pull out the wiring, socket and switch assembly
  • Desolder or snip the wires near the end of the terminal

Step 3: Soldering in the New Wire

  • Once you get to a clean terminal end or have one with a couple of wires off of it, insert it back into the handle and NOTE how it is keyed to fit one way.
  • Close the handle and assure a good fit
(you could use the battery and see which terminal side is +/-. I dotted my terminal with RED for +
  • Reopen the handle, remove the terminal and attach to your wires
  • We used an old extension cord to connect to the terminal
  • Solder in the 2 ends
  • Insert the terminal and wire into the handle as shown
  • I snaked the wire through some of the guides which made it feel tight but you could try and tie a knot or wiretie in something for a strain relief.
  • Close the handle, insert screws and tighten down.
  • Making suring the other end of your cable/wires are capped (NO CROSSED WIRES!) insert the battery to assure a good fit/click.
  • If things do NOT feel right, be sure you inserted the terminal/socket in the right way as it's easy to get it wrong (50/50 chance)

Step 4: Drilling and Switch Selection

During our 3 projects, we ended up using 2 different type swtiches. Note that they all are 3A+ SPST (Single Pole Single Throw). This means that a full click will be on (and stay on) and another click will be off (and stay off).

2 switches were push button switches (DM and JD used these) and the other was a rocker switch (NZ's bike).

We purchased the gold (bling) colored switch at home-depot for $3.81 while I used a switch from a local shop for $0.20. Point? Check/dig around and be sure it can handle 3AMPs or more!

  • Depending on your switch, drill out a hole at the bottom of the female PVC cap. In this picture we are drilling for a rectangle rocker switch. We did have to use a drummel to shape the hole for a good fit. If you don't have/want to do this stick with a rounded switch which uses just a single drill/hole.
  • Insert your switch into the new hole. Using the included nuts/lock-washer (if included) to mount it tight into the PVC cap.
  • In the rocker installation we used the green (extra) wire in a knot for strain relief.
  • Using the size of your wires/cord drill a hole in the flat side of the PVC cap.

Step 5: Light Housing Assembly

The main housing is the "No Hub Coupling".

Notice the small lip/ridge that's inside the rubber tubing. We'll be using this as a stopper for the front-edge of the light.

Push the lamp into the coupling until it meets up with the lip/ridge inside.

Plug in the MR16/MR11 Socket to the end of the bulb.

Push the white female PVC cap onto the end until flush.

Screw-down/tighten the coupler keeping in mind that the outside (lamp facing) should only be snug (don't go crazy as there is nothing underneath holding it back except the lamp). Take some time to tighten down the one that surrounds the PVC cap.

Step 6: Connecting Light, Switch and Battery

Now the (semi) hard part. Putting everything together.

  • Connect a wire from the switch to the socket on the lamp.
  • Extend the other socket connection out through the hole of the PVC cap.
  • Take the the other (free) wire from the switch and extend it through the PVC cap.

When you are done you should have 1 wire from the switch and 1 wire from the socket coming out through the hole. See the (BASIC) wiring diag pic for more info.

OPTIONAL - We used MOLEX (quick-connect) connectors between the light and the battery pack. If you don't have these you could simply hard-wire

Before you close things up, it would be worth it to test the unit out. Again, before plugging anything in be sure that your wires are not crossed or shorted! (heck put on those safety glasses too!)

Once everything looks good, you'll need to twist on the cap. My trick was to give the cap a couple of BACKWARDS twists before I screwed it on. If you don't do this the wires may can wrapped up while you're twisting things on.

Once the cap is on, give it another test to see if we're a go!

Step 7: Bike Mounting and Finish

Position the ballcock washer between the 2 pipe-clamp screws. This will be used as a cushion for the light (I was worried that directly connected it might shake the light to death)

Using the hanger and extra (3rd) clamp tighten it down over the washer as shown in the picture(s).

Recheck the position of the washer while you are tightening things down. Make sure it doesn't shift over to the side (like ours did).

Recheck the fittings, wires, screws, etc. Hook up the power and from there your're done!

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    25 Discussions


    4 years ago

    Little late to the game, I know, but I would love to see someone do this build with some Bosch 12V 2.0 Ah Li-ion drill batteries. Has anyone tried this with a 12V battery system similar to the mini Bosch for factor?


    10 years ago on Step 7

    Hi, could you please also show a picture of the light working? Nice project tho, I have also a 18V battery on my bike, but I am powering LEDS. Halogen is better I guess. What would you prefer, halogen or LED? Thanx


    Reply 12 years ago

    Ugh... I knew that was gonna give me trouble :) I should have photoshop'ed a diff name in.


    11 years ago on Introduction

    I cheated and bought an old nightsun lighting system for my light base, but I needed a battery. That's where I used this idea. I was lucky, I had an old no-name brand drill that was exactly 12 volts, so I don't have to worry about burning out my bulbs. What makes this solution for holding the battery in an old water bottle is the fact that it leaves a lot of extra space in the bottle for a small tool kit. I have a patch kit, some allen wrenches, and several screwdriver bits stuffed in mine. Just be sure to put them in a little baggy, so you don't have to worry about shorting any wires.


    12 years ago on Introduction

    I am considering making this light with the 18v mod. However I have concerns about heat and battery life. I have this same Ryobi battery and charger. Could someone please report how long it will run on one charge? Also I know that 20watt bulbs run hot, and overdriving them can only make them run hotter. Is heat an issue with this setup? Thanks in advance! Nick

    2 replies

    Reply 12 years ago on Introduction

    The battery will last for 40 minutes of bright light Heat is not an issue with a metal light housing as long as you keep moving. I'm not sure how the plastic one would do that is detailed here. A 5000 hour bulb will only last 25 hours with this setup. I've been on about 10 rides totaling 7 hours without a blown bulb. I'll report what happens when a bulb finally blows. Hopefully it wont be too destructive.


    Reply 12 years ago on Introduction

    Thanks for the reply. I would need at least 2 to 3 hours or run time from the lamp to make it feasible for me. My average ride lasts 2 hours (or more)

    I am still building the light but will step down my volts a bit to get some more run-time. Looking at this battery as posted in the VeggieCycle thread.


    12 years ago on Introduction

    I set up my light (a simple malibu landscaping 12 volt spot light) with this battery system tonight. Loved it. Rode for 40 minutes at 20mph and the first battery back was still going string. The light is REALLY bright. Just be sure to bring a back up light and a spare bulb just in case.


    12 years ago

    the light i made is waaaaaaay better then any thing you can buy or i have ever bought. i use a small 12v 7ah lead acid batt shoved in a large stash bag on a 50W halogen bulb to solve the current problem. I only ride home at night on tuesdays from work- luckly on a tuesday i dont have to bring my laptop and other CArp so its a comprimise on weight to the rest of the week. i do have a problem though cars dont like my super high beam!! and they make it VERY clear even if i dip the light ive even changed to a smaller watt bulb still dosent help can u?? (i originally used super bright LEDS but these were even worse{ even brighter)- they only ran off 6V nicd!!


    12 years ago

    I had been keeping my long broken Ryobi drill around thinking I could use it or some part of it for a project, and did basically the same thing to power my LED bike lamp project. I have it running 2 3w LEDs through a buckpuck and it runs long and bright. It's similar to other LED bike lamp instructables but with my own twist on the enclosure. Nice work.


    12 years ago

    These Halogen lights consume way too much current to be used practically. Might as well buy a 12 volt car headlight and use that.


    12 years ago

    You have to take apart a flashlight to make a bike light. Which is cool but what I would really like to see would be some kind of instructable on making custom battery connectors for power tool batteries, e.g. with cardboard, tape and copper strips.

    1 reply

    Reply 12 years ago

    Seriously, power tool batteries are durable, affordable, and ubiquitous. DeWalt and Ryobi are both adding all kinds of tools to their 18-volt lines, so those look like the targets to hit for the moment. Personally I'd like to see a "reverse" button on the in-vehicle charger, so I could dump a few power tool batteries into a dead car battery to start the car. ;) As far as building your own connectors goes, it doesn't look hard, you could probably make some progress in a weekend. Let us know what you find!