This is a Bike Powered phone charger that is cheap, 3D printable, easy to make and install, and the phone charger is universal. It is a useful thing to have if you ride your bike a lot and need to charge you phone.

The charger was designed and built by five teens at Vector Space in Lynchburg, Virginia.

Supplies

Generic Generator, $12.97
LM2596 voltage regulator, $6.99
2 USB ports, $2.22
4 diodes, $0.56
4700UF Capacitor, $1.95
100 ft of Red Primary waire 22 GA 22 GA, $7.76
M3 screw x 30mm socket head,(hardware store) $0.49
3D Printer Filament PLA (65g total for box, handlebar clamp, and phone holder), $1.30
Rubber Bands
Velcro

Total: $30

Step 1: 3D Printing

Phone Holder

I, sir James, through many trials and tribulations, designed a phone holder that will mount on most bike handlebars. It’s made in two parts. The first is the handlebar mount, and the second is the phone mount.

Handlebar Mount

The handlebar mount is attached to the handlebars and held on by a screw. You can use an insert nut on one side of the mount, and drive a screw from the other side. I designed the mount to use an M3x20mm screw. See the video in the assembly step.

Another key component of the handlebar mount is the size of the large hole. Our design has a 27mm hole, which gives it just enough space to be securely clamped to our handlebars. If your handlebars are a different size, you can access and modify our TinkerCAD design here.

The phone is held by two rubber bands that goes through the holes of the phone rest to keep the phone in place. You connect the phone rest to the handlebar mount by super gluing them together. This is a universal phone holder that means it works for all phones.

Electronics Enclosure

We also used TinkerCAD to design our electronics enclosure. You can access the design and modify it here .

The purpose of the box is to protect the circuit. The box is designed this way so it can be tied to the bike and to let the USB cords pass in and out. Our only consideration with material choice was whether it would be waterproof. We found that all of the major plastics meet this requirement, so we decided to use PLA because of its low cost and ease of printing. The electronics enclosure takes 41 grams to print, which costs approximately 82 cents.

We printed everything on a Lulzbot TAZ 6 using PLA at 0.25mm layer height and 20% infill. No supports necessary.

Step 2: Electronics

AC to DC Conversion

The generators produce AC voltage, which needs to be converted to DC in order to charge a phone. We used a full bridged rectifier to convert the power then a voltage regulator to bring it down to 5v so it wont fry the battery of your mobile device. We also put a 4700uF capacitor on it to make it charge more smoothly then it goes out to the output USB. We used 22 gauge copper wire to connect everything.

A full bridge rectifier is made from four diodes placed in a specific configuration. You can find details of how to build one here, keep in mind, you don’t need a breadboard, you can solder the diodes directly to one another. See how we did it in the picture show

the pin outs you wont to use are the farthest left and right pins to solder to the wires if the USB ports are stacked then you wont to use the ones in front if you are using the one closest to the pins

Voltage Regulation

In order to convert from voltages above 5 volts to exactly 5 volts, we used a LM2596 voltage regulator. The output voltage of this regulator can be adjusted by turning the small screw on the blue box. In order to set this screw properly, we connected a digital power supply to the input pins at 9 volts and we measured the output voltage with a multimeter. While doing this, turn the screw and watch the output voltage until you get as close as you can to 5 volts. If you go over five volts, your phone will be fried so it is important to get it as close as you can to 5 volts. Use a small flat head screwdriver to turn the screw. Next, you want to solder the red wire to the hole labeled in+ and the black wire labeled in-, then you want to do the same thing to the other side

Step 3: Assembly

The phone holder and handlebar mount are connected to each other using super glue. Insert a rubber band through each of the two holes in the phone holder.

Place the electronics into the box, plug the USB cables into the USB ports, then hot glue the electronics in place. Make sure to get the input and output correct with the labels on the box.

The generator we used came with a clamp piece to attach it to the bike. It was fairly simple there were two bolts for the clamp that goes on the bike. We attached it to the seat stay. Make sure it is under the wire for the shifter so it wont interfere with it. It is easiest to put the generator on the attachment piece before you put it on the bike.

Step 4: Installation

Electronics Enclosure

The box is attached with Velcro so you can put it where you want on the downtube. Put the Velcro strap in the tab slits and then make sure it is nice and tight on to the place you put it on.

Generator

To install the generator you have to screw the generator to the end of the bracket first then screw the bracket on to the seat stay of the rear end of the bike and screw the bracket to the generator. When you do this you need to make sure that the end part is pushing hard enough, but not too hard or that will effect the tire pressure. Before you start riding your bike you will need to make sure that the screws are on tight enough so the generator won't fall off. You will also need to keep the center axis of the generator pointing toward the center of the wheel.Then you will need to attach the wires to the bike generator and then attach the other end of the wires to the USB port at the end of box that says "Input". Then you put your own USB cable into the "Output" hole on the other side of the box and plug your own charger into your phone.