10€ BICYCLE USB CHARGER

by Vulcaman

83K43437

Intro: 10€ BICYCLE USB CHARGER

Hi,

in this Instructable I want to show you, how to create your own Bicycle USB charger for a bicycle dynamo for less than 10€.

This summer, I took an bicycle tour with my friend for around two weeks and we had the problem that we don't had access to a power socket to charge our batteries for our GPS devices and smartphones. So I searched for an solution.

The first Idea was to use a solar charger. Solar charger works great when the sun shines, but when it is cloudy they didn't work really well.

The second Idea was to use the hub-dynamo from my bicycle to produce the power for charge my electronic devices. This is the best solution, because I am not limited by the weather and I can even charge my devices at night. However hub-dynamos don't produce a regulated 5V voltage to charge my devices over USB, so I created a simply circuit that will transform the unregulated AC voltage from the dynamo to regulated DC 5V. I tried to build the USB-Charger very professionell and waterproof, so that it will look great on my bicycle.

All in all this charger is an awesome device for Bicycle-Travellers, Geocachers and Camper, who don't had access to an powersocket, but don't want to travel witouth electronic devices.

Specs of the charger:

INPUT: 6V 3W hub-dynamo ( Voltages can be higher than 6V when no load is connected to the dynamo !!! )

OUTPUT: 5V (max. 700mA) USB regulated voltage
charging stars at 10km/h (Megallan Explorist 310 GPS and cheap powerbank succesfully tested)
nearly completly hidden in the 1inch steeringrod
watertight
puffered voltage with additional powerbank
overvoltage protection
modern design

### If you like my Instructable, please vote for me in the Powersupply Contest and Travel Contest###

#### Update 21.01.2022 ###

New Version V3.1:

I have built a new charger with a lot of improvements. The new charger has additional Supercapacitors for energy storage and the charger can give out 1A at 5V at normal speeds (~18-22km/h). Also the charger will not get warm due overvolatge. Please take a look at my Website Fahrradlader.de, there you will find a lot of informations about the new charger (German only). I will write an Instructable soon in the next Time.

#### Update 02.10.2021 ### New Version V2.1: I have built a new charger with a lot of improvements in Efficency and Safty, please take a look at my Website (German only), I will write an Instructable soon in the next Time :

STEP 1: Fusion 360 File

The USB Charger is completely designed in Fusion 360. Here is an interactive model of the charger:

If you can't see the interactive 3D model above, its probably because
you're not using a WebGL-enabled browser, or you're using the Instructables Mobile app)

All Fusion 360 files can be downloaded at this link: http://a360.co/2qsgFhA

STEP 2: Required Parts

Electronic Parts:

Here are all required parts for the USB-Charger. I tried to source all parts as cheap as possible. Often I had to buy more than I need, so you can easily build up to three chargers with this bill of materials.

Quantity Description Link Price 1x USB-A plug female
Aliexpress 0,64€ (for 5 pieces)
1x Stepdownmodule MP1584
Aliexpress 0,48€ 1x 680µF 25V polarized capacitor
Aliexpress 2,40€ (for 20 pieces)
2x 220µF 50V polarized capacitor ultra low ESR
Conrad 0,7€
1x Surpressordiode 1.5KE22CA Aliexpress 1,28€ (for 20 pieces)
4x SCHOTTKY DIODE SR5100 100V 5 A
Aliexpress 0,91€ (for 20 pieces)
1x Bimetall switch NC KSD9700 50°C
Aliexpress 2,32€ (for 10 pieces)
1x 10x7cm PCB single side (enough for 3 chargers)
Aliexpress 0,72€
some Wires

Mechanical Parts:

QuantityDescriptionLink
1x

Screw M5x50mm DIN912

local hardware store
1x

M5 Hex Nut

local hardware store

3D-Printed Parts:

Please print the parts in a heat resistant material. Otherwise you will have problems on hot summer days with melting parts. You can download the .stl files at the bottom of this step.

### You can purchase all the 3D-Printed Parts on my Website: https://www.vulcaman.de/ ###

Quantity Description How the Part look like
1x AheadRing.stl

ClampingRingTop.stl

ClampingRingBottom.stl

Etch template:

Here is the etch template for the PCB. I am using the toner transfer method to make my PCB. So you have to print out the attached pdf and transfer it to the PCB. Also this is my first project with Autodesk Eagle so I am giving my best to create this PCB :-) . You can download the .pdf file at the bottom of this step.

Quantity Description How the Part look like
1x

Etch template.pdf

STEP 3: Let's Take a Look at Your Bicycle Wether It Is Compatible With This Charger or Not

Requirement:

Hub-dynamo (normal dynamos didn't work so good, because of an bad efficiency)
1 inch steering rod
removable Ahead-ring

Here you see an example of a bike which is compatible with this charger:

STEP 4: The Circuit

The circuit of the charger contains of three different circuits:

Circuit 1:

The first circuit is an bridge recifer and an voltage doubler refered to Delon. This is the key feature of this chargers, because with the voltage doubler I can charge even at lower speeds >13km/h . Which makes it really comfortable for long distance riding.

Circuit 2:

The second circuit is my overvoltage protection. Here I coupled the bimetal switch with the suppressordiode. If the voltage rises over 22V, the suppressordiode opens and protects my DC-DC coverter from an over voltage. Also the suppressordiode is protected by the bimetall switch. So if the suppressordiode opens and burnes the complete power, it will get hot after some time. To protect the diode from too much heat and an potencial heat damage, the bimetall switch is coupled to the diode. So if the temperature is getting to high ( >50° ), the bimetal switch will cut of the main voltage from the charger.

Circuit 3:

The third circuit contains of a MP1584 DC-DC-Coverter. This coverter will convert the unregulated voltage from 6-22V DC to regulated 5V DC for the USB power . The converter has an efficiency of max. 96%, which is great for this project, because I am trying to build the circuit as efficiency as possible.

STEP 5: Etch the PCB

What you need for this step:

QuantityDescription1x

EtchTemplate.pdf

At first you have to print the EtchTemplate.pdf with an laser toner printer to a glossy sheet of paper. In my case it was an electronic catolog. Once the pdf is printed to the catalog, clean your single side PCB with aceton, to make sure that the pcb is free of fingerprints.Then you can start tranfering the Toner with an steam iron. Once transferd you should check, if your toner transfer was succesfull.

Now you can etch the PCB in the etch material of your choice. In my case I am using Sodium.

After some minutes, the PCB is completely etched. Now you can remove the toner with aceton and check that everything is etched fine.

Then you can start drilling the holes for the electronic parts. Here I am using an one milimeter drill.

Now your Board is etched, drilled and ready to assemble.

Also please take a look at this Instructable from which I learned the Toner Transfer.

STEP 6: Assemble the PCB

What you need for this step:

Quantity Description

Stepdownmodule MP1584 adjusted to 5V DC

680µF 25V polarized capacitor

220µF 50V polarized capacitor ultra low ESR

Surpressordiode 1.5KE22CA

SCHOTTKY DIODE SR5100 100V 5 A

Bimetall switch NC KSD9700 50°C

1x Etched and drilled PCB

some

isolation tape or heat shrinking tube

At first you start with the small components. Place the four Schottky diodes at the right side of the PCB.

After that you can mount the preadjusted to 5V Stepdownmodule and the 680µF capacitor at the left side of the PCB.

Now the safety switch of the circuit, which prevent an over voltage damage of the stepdown module and the charged devices, will be installed.

If the suppressor diode will get to hot, the bimetal switch will cut of the complete voltage from the charger. For an improved heat conduction, I've added an little pice of metal, which will clip the switch and the diode together.

Once assembled, you can install the diode and the switch to the PCB.

Then you have to attach the two low ESR 220µF capacitors to the PCB.

Finally you can mount two little connectors to the PCB.

Now the PCB is ready for the next step.

The PCB needs to be protected from dust and it needs to be isolated from the steeringwheel. The best solution for this task is a hugh heat shrinking tube with an diameter of 25mm. Sadly I don't had acces to heat shrinking tube in these dimensions, so I had to use isolation tape for my application. Try to stick the isolation tape as tight as possible to the charger.

STEP 7: Installation of the Ahead-Ring

What you need for this Step:

QuantityDescription

USB-A plug female

AheadRing.stl

little wires; lenght about 8cm

XH2.54 2 Pin plug

some

silicone

At first you have to solder the the two wires to the USB-A plug. Isolate it with some heat shrink tube. After that you need to crimp the XH2.54 plug to the wires. For the right orientation of VCC and GND, please refer to the pictures below:

Next you have to insert the pre assembled USB plug to the Ahead.stl 3D-printed part. Once the USB Plug is inside the printed part you take some silicone and glue the USB Plug and the printed part together. I am using silicone, because I want to make sure that my charger is waterproof and protected against dust.

STEP 8: Prepare the Ahead-Ring

What you need for this Step:

QuantityDescription

pre assembled Ahead-Ring from Step 7

ClampingRingTop.stl

ClampingRingBottom.stl

Screw M5x50mm DIN912

M5 Hex Nut

At first you have to insert the M5 hex nut to the ClampingRingBottom.stl. After you simply put the ClampingRingBottom.stl inside the ClampingRingTop.stl. The parts are designed for clamping. If the ClampingRingBottom.stl gets pressure in vertical direction, the ClampingRingTop.stl will be spread. Later this feature will hold the Ahead-Ring in place.

Next you need to screw the Clamping-Ring to the Ahead-Ring together by using the M5x50mm screw. Don't screw it to tight. At this time the screw needs to move freely.

STEP 9: Adjust the Steering Rod

Now it is time to adjust the steering rod, to make some space for the PCB.

At first you need to remove the Ahead-ring.

As you can see on this picture, the Ahead-ring is screwed to this snap ring. To make some space for the PCB, you have to push the snap ring deeper inside the steering rod.

I am using a metal tube and a hammer to push the snap ring inside the steering rod. You have to push the ring 18cm inside the steering rod.

As you can see the snap ring is deep enough:

Now you can test, If the charger fits inside the steering rod:

So you have prepared the steering rod and you are ready to start with the electrical installation of the charger.

STEP 10: Installation of the Charger

What you need for this step: QuantityDescription

two pole wire with XH2.54mm plug

pre assembled PCD

pre assembled Ahead-Ring

At first you need to create a connection between your dynamo and your PCB. I made it simple, because I go directly to the two powercables from the dynamo. To create a better look, I wired the cables inside the bicycle lamp together. For that you have to open the lamp and take a look wether there is enough space for a wiring like this.

Now the most of the work is done. You just have to connect the charger to the XH2.54mm plug. Please check the orientation of the charger in the picture below. Otherwise your charger will be damaged.

Then it is time to push the PCB inside the steering rod. Once it is inside, you have to install the Ahead-Ring by simply connecting the XH2.54mm plug from the Ahead-Ring to the PCB.

After that you can push the Ahead-Ring inside the steeringrod. But make sure that the wires are inside the wire-channel (see picture)

Once the Ahead-Ring is in place, you need to take a screwdriver and tighten the screw, until you feel that the Ahead-Ring will not move anymore.

STEP 11: How to Use the Charger & Troobleshooting

Usage

The usage of the charger is realtivly simple. Just connect your device with the USB-Plug inside the Ahead-Ring and your are done.

The charging process will beginn at 10km/h. However a stable charging situation will be reached at 13-15km/h. The current which is available at this situation is around 500-700mA. For charging an powerbank or a GPS device, this is more than enough.

Devices with an power consuption of over 700mA can not directly charged with this charger. For these devices (smartphones, tablets...), I recommend to use an powerbank as a puffer battery for a succesfull charging process.

Troobleshooting:

My charger stops charging after some time of riding. What is the problem?

Explanation:

Because your dynamo produce to much power and your device which you want to charge needs only a piece of the produced power, the voltage will rise and the overvoltage protection of the charger will cut of the complete power from the charger

Solution:

You need some extra devices, which have to been charged so that the voltage will drop and it will not activate the overvoltage protection. Turn on your Lamp or connect a second or a more power consumable device to the charger. This should solve your problems.

31 Comments

TiboKnockaert 14 days ago

Hello, what an idea this is! With everything needing electricity these days its hard to meet a cyclist who didn't run out of electricity in one of his many devices during a ride. As a cyclist myself I've recently bought a frame bag to carry a powerbank with me along the way for if I ever run in this problem again. This idea however is much more aerodynamic and, more importantly, much cooler! However if I would make this project myself I would make some small adjustments to my needs (because I don't have a dynamo to charge while I ride). This would be:

-Removing the batteries as charger but more like a powerbank.

-Changing the port to usb-c with input and output in the same port (cause a second port would be to tall).

-A system so I can push the port inside so it would be more water resistant.

-Adding a led indicator to see if I almost need to charge the whole thing.

-A 3D printed tube for the whole so it's not in all different pieces but comes out in one go.

This would make this excellent project for me perfect. Thank you for this instructable filled with inspiration and wonderfull insights in the electronice in all of this!

muncie1963 8 months ago

Hello,
Just wundering would you be able to send me one without the Dynamo.Of course i pay for shipping,parts and your time.Im not electronically fit.Greetings Tom.( would have to be sent to the USA)

ondrejp_sk 1 year ago

Hello Christian,
I like this design as it is simple enough to be built with through-the-hole components on a prototype circuit stripboard similar to e.g. this https://hokkaidowilds.org/diy-bicycle-dynamo-usb-c... unline your later designs.

I have a few questions about this old design.

1. how have you chosen the capacitor values ?
- why 50V when the step-down IC works with only 25V and the supressor diode clamps the voltage down to 22V anyway ?
- why the capacity of 220uF ? is it somehow related to the resonance https://fahrradlader.de/funktionsweise/gleichricht... or is it an arbitraty value. What would happen if replaced with a smaller voltage / larger capacity ?
- don't the two 50V capacitors need something to protect against overvoltage when no load is connected ? (when analyzed the currents flowing in the circuit, I think the 2 additional diodes in the 4 diode bridge actually helps protect the capacitors as overvoltage is sinked through the single supressor diode)

2. when I googled Delon voltage doubler, it uses only 2 diodes and 2 capacitors. Is the 4 diode full wave rectifier needed here ?

3. What were the disadvantages of this that forced you to design v2 and later v3 circuits ?

AdrienR 5 years ago

Really smart! I like the Delon doubling voltage. I did not know this circuit. I found it on the simulator falsade.com and observed that mainly two diodes are working (when Uin is low). Do you have problems with diode aging when you go faster?

Thank you in advance

Vulcaman 5 years ago

I am glad you like it. Until now the circuit is successfully in use and I don't have any problems with diode aging. But I have to say, that I always use a lamp in parallel to the charger, when no big load is attached to it, so that the suppressor diode will not overheat that often.

vandrewskis 3 years ago

Great job!!! I was also about to use piece of this instructable for my project. Namely Circuit 1: the bridge rectifier + delon. I've tried both in simulator and in reality and it works... However looking at delon only - I'd expect it should be enough with 2 diodes - as @AdrienR pointed out. What is the reason to use delon + two diodes?

minimeccanica 6 years ago

Nice instructables and very well documented. One criticism, one suggestion for improvement and one question.

suggestion for improvement: to wrap the PCB with normal tape leaves some "crevices" for humidity to attack the soldering. There is a tape (black) with once in contact with oxygen "melts", and if you wrap your PCM with that you obtain a "cocoon" absolutely water-tight (that tape is just for electrical contacts outdoor)

criticism: why the plastic sold has a seat for a V-shaped bolt and the bolt has a plain head? A V-shaped bolt would make a tight seal against the V-shaped hole in the plastic

question: 500-700 mA seem quite a reasonable current for a smart phone to charge (I personally would be scared to charge mine at higher pace), do you deem that for normal phones a higher current would be required?

Anyway, my heartfelt compliments

Manlio

Vulcaman 6 years ago

Thanks for your comment!

Do you have a link for this kind of tape? It sounds really interesting.

Well, the small fillet at the Aheadring.stl is just a design element. If you take a closer look at the plastic part, you will see that the small fillet has no function. Also the plain head bolt sits on an plain surface.

I can only talk about my smartphone, which requires 1,5-2A for fast charging. If the current is under 1A, it takes a lot longer to charge nearly. The charging time nearlygets quadruple. For normal phones I think 500-700mA would be more than enough. However the charging current is different from phone to phone. I would take a look at the original charger of the phone first.

crosbyvista 3 years ago

https://www.amazon.co.uk/Black-Self-Amalgamating-Waterproofing-Connections/dp/B000KH9UHM tape you require

minimeccanica 6 years ago

The sticky tape, which undergoes a kind of "rubber vulcanisation" (melts together) is sold as a commodity in every shop of electrical gear, home appliances.Another suggestion came to me: to clip together the thermal switch and suppressor diode you could use also the "cement" used to glue together the heat sink to CPU in powerful computers (which develop a lot of heat). A friend of mine used it with Peltier cells to cool down his beer reactor during hot season with satisfying results. Said "cement" conducts heat very well but NOT electricity (very strange.....)

Yard Sale Dale 4 years ago

It’s an interesting device. I have seen other ones that used skateboard wheels and tire dynos, to lower resistance and not eat tires not made for dynos.
The headset cap and star nut are not redundant. They maintain bearing tension during fore/aft shock loads on the fork that will work the stem loose without them.

prikola1234 4 years ago

Hello, I have problem finding " 220µF 50V polarized capacitor ultra low ESR". Is low ESR instead of ultra low ESR going to work?

kavish laxkar 6 years ago

Nice one..:)

CraftAndu 6 years ago

Really nice ´ible. Voted!

KrzysztofŻ18 6 years ago

If anyone need more than 500-700mA there are 2 simple steps to follow:
1. Use step up step down 5V voltage regulator ie. Pololu S9V11F5 or something similar

2. Short pins D+ and D- together (this tells smartphons and other electronics that this is wall charger)

ikijano 6 years ago

Input voltage range of that regulator is way to low. Dynamo will burn it quickly.
You really need regulator which input voltage range is wide enough.. about 6 to 70 volts would work just fine.
Finding that kind regulator is challenging.

KrzysztofŻ18 6 years ago

I forgot that changing hub-dynamo to 5W helps a lot too.

zposner 6 years ago

Really nice!

HP_II 6 years ago

Great write up, about the best I have seen just for the format, and a brilliant idea.

I have one question / concern though. Looks like the star nut is not used any longer with this setup. Just mentioning here that the star nut is used to preload the headset bearings, which is a bit redundant once the stem is on. However if the stem were to loosen there would be no easy way to reset the preload, and the star nut may also help to keep the bars attached to the bike if the stem were to become loose (sort of a backup).