Homemade 12 volt generator for a bicycle. High power bicycle pedal generator for recharging batteries

I just recently bought a bicycle for commuting to work, and in general, to ride and enjoy cycling. For safety, I turn on the front and rear lights so that participants traffic I was noticed better. My LED flashlights run on two AA batteries. And the charge only lasts for 4 hours of driving. Actually, this prompted me to think about purchasing a bicycle generator that could power all the lights.
I didn't find anything in stores. All flashlights are battery powered. Then I decided to make a generator for the bicycle myself, from whatever came to hand, so to speak...

And then I remembered that I once made a generator from a stepper motor. I decided to repeat the idea. But where can I get a stepper motor? They are found in almost all office equipment. I went into the closet and found an old printer. Naturally, it contained a pair of stepper motors. I took some, I don't need any more.

What else do you need for a generator?

You will need a few things if you want to build a generator for your bike. Here's what they are:

• - Stepper motor from a printer or other equipment.
• - 8 pieces of diodes, any, for a current of 0.5 -
• - Voltage regulator LM317 –
• - Radiator for LM317 -
• - Development board -
• - Switch –
• - Housing for regulator -
• - Wires.
• - Mount from the wing.
• - A wheel from a car.

Regulator circuit with rectifier

We need to assemble a voltage regulator so that it not only rectifies the current from the stepper motor, but also regulates the output voltage, thereby protecting the LEDs from voltage surges when driving. The regulator circuit is simple. Diode rectifier bridge and voltage regulator on the LM317 chip.

I assembled everything on a breadboard with holes. I simply inserted the parts, bent the contacts in the direction of soldering and soldered everything together. I soldered the wires and now my regulator-rectifier is ready.

The toggle switch can be used to turn off the generator.

Generator assembly

We assemble the mount of the stepper motor to the wheel. The principle is simple: the wheel is rotated by a stepper motor, the motor generates electricity.
I thought for a long time about how to implement the fastening in a simpler and more reliable way. Here's what I came up with:
I took the mount from the wing (boot, mudguard). I screwed an aluminum corner to it, trimming it a little. And I already attached a stepper motor to the corner. That's it - the design has been tested and works fine. Of course, it would be desirable for it to spring the engine to the wheel, but in principle, this is quite normal.
Oh yes. A machine wheel with a rubber tire is placed on the stepper motor. Electrical tape is wound around the motor shaft so that the wheel is pulled tightly onto the shaft. Nothing better came to mind.

Regulator mount

I also thought for a long time about where to place the regulator body, where to attach it, because it must be in the vicinity of the stepper motor, otherwise I will have to pull 4 wires from the stepper motor.
Finally, I came up with an idea and decided to mount the regulator on stands on the same bar where the stepper motor is mounted.
I cut a rectangle out of thin aluminum foliage and screwed it with long bolts through 1 cm long posts. Well, I attached the regulator to the rectangle.

Checking generator operation

The stepper motor I took was 24 volts. And at normal bike speed it produced more than 30 volts. The output regulator produced 3.1 volts. Which is quite normal. If you are not satisfied with this voltage, adjust it with 150 and 220 Ohm resistors. In general, you can solder a variable resistor and adjust the voltage as you like.

I connected the wires from the regulator to the front light. Connected in parallel with the batteries. As a result, when the bike is stationary, the light shines from batteries. And when the bike rides, the lamp shines from the generator, and the elements are slightly charged. Ideally, of course, you need to use batteries, but AA batteries with a voltage of 1.2 volts, the flashlight will burn dimly. In principle, you can throw out the batteries altogether, and the headlight will only light when you are moving. In general, whoever wants it.

There is a special device that can generate power energy. Such a device is a bicycle generator. The resulting electricity is absolutely free. The production process occurs by scrolling the pedals. According to the types of bicycle generators, there are 4 types:

• Bottle.
• Bushing.
• Contactless.
• Carriage.

The frequency of pedaling is quite closely and almost inextricably linked with the output of current and voltage. This reproduction is typical for all types of generators. The bicycle generator produces only alternating current. To ensure constant current, it is necessary to install a rectifier bridge. It consists of specialized diode lamps. Or you can install a two-half-cycle rectifier. You can buy a generator for a bicycle in special stores, as well as at car markets.

Bottle generator for bicycle

This type of generator is called a bus generator. By type it is a secondary value generator. The bicycle bottle generator consists of a housing that is completely insulated. On the outside there is a special roller that is designed for rotation. It is tightly attached to the body, that is, to the plug. Also, the filling of this generator consists of a conventional copper winding and a magnet. The movement of a field of magnetic origin occurs due to the contact of the roller with the tire of the bicycle wheel. Based on this, energy is transferred from the wheel to the mechanics.

The faster the wheel rotates, the faster the roller on the generator rotates. Maximum polarity is achieved in the generator itself, and voltage is reproduced.

The positive side of this type of generator is:

• Low price relative to other types.
• Easy to install on a bike.
• The device can be easily turned off or on by moving away from the bicycle.

As for the shortcomings, they are not so significant:

• The tire begins to wear out over time.
• It takes time to set the incline level.
• The appearance of sound due to friction against the tire, especially at high speeds.
• Slight misalignment of the wheel due to the weight of the generator, which ranges from 200-250 grams. This is connected due to its fastening on one side.
• If the weather is rainy, the generator does not operate at full capacity. The friction on the wheel is insufficient due to sliding.

But taking into account these disadvantages and advantages, in general, this type The generator is quite efficient.

Contactless generator for bicycle

Electricity is supplied through the operation of a bottle generator. The carriage also produces current. In another way, this type of bicycle generator is called a hub dynamo. The name comes from the fact that there is no contact between the generator and the wheel. The current appears as a result of close contact of the rim to the generator. This is what causes the magnetized field of the wheel rim to form.

The lighting diode is directly installed in the device. The voltage goes directly, without any additional stabilization devices. Positive aspects of this device is:

• No friction factors on the wheel.
• Compact and light weight, up to 70 grams.
• There are no connection cables.

The headlight, which is located at the front, is installed on the fork. Taillight - rear. Based on this, these flashlights are independent in themselves. They burn not due to batteries, but due to the rotation of the wheel in a magnetic field. The quality of lighting is at a sufficient level. When riding a bicycle in slow motion, the lights should go out, but this is not the case. This does not happen due to the fact that a special capacitor is installed. In essence, it can be called a battery that gains energy while riding a bicycle.

Conclusion

Using a bicycle generator is beneficial. Firstly, absolutely free electricity generation. Secondly, convenient and comfortable road lighting at night. The 12 volt DC bicycle generator is convenient to use and easy to install. It can also be assembled almost quickly. Does not take up much space during transportation. A bicycle generator does not cause any harm.

A bicycle generator is a device that allows you to receive electricity by rotating the pedals and transfer it to lighting fixtures bicycle or third-party electrical appliances. By design, bicycle generators are divided into several types: bushing, bottle, carriage and contactless.

The current and voltage output are inextricably linked to the pedaling frequency - the speed of movement. The pattern is valid for all types of generators. The bicycle generator produces alternating current, which is stabilized into direct current using a bridge rectifier. Its role can be played by soldered diode lamps or special devices, for example, a full-wave rectifier.

Hub dynamo as an electric motor

A hub dynamo, or bushing generator, is a regular one with a built-in magnetic mechanism. During rotation, eddy currents are formed; at the exit from the bushing, mechanical energy is converted into a current with a given force, voltage and power. On bicycle dynamos, the voltage reaches 6V and the power is 1.8-2 W.

The invention was patented by the English company Sturmey Archer. Nowadays, production is actively supported by other manufacturing companies - Shimano and Schmidt.

Features of the generator bushing design:

• fixed armature (winding) on ​​the axis;
• a ring magnet fixed and rotating together with the bushing;
• terminals and double wires;
• high mass.

Dynamic Shimano AlfineDH-S701

The bushing source of electricity does not use the bicycle frame as a ground and, together with the lamps, is isolated from it. In a full-wave rectifier, the AC circuit (output) and DC circuit (to the headlight) are completely separated from each other.

Hub dynamos are heavy, however, lighter rare earth magnets and an aluminum shell have made it possible to slightly reduce their weight. In operation, the device has low resistance to unwinding, and as the angular velocity increases, the frequency of the current increases. This effect smoothes out the voltage gain and allows the generator to operate at wide ranges speeds

The headlights that the bushing generator is equipped with have a built-in current stabilizer. When connecting another headlight, a separate rectifier is installed in the circuit so as not to burn the electrical appliance. The brightness of the headlight depends on its requirements for the energy source and, in fact, the output voltage of the bushing. The greater the discrepancy downward (the headlight is more powerful), the dimmer the light will be. In the opposite situation, the light source will not work.

Bottle bike generator: features, pros and cons

Let's get acquainted with another energy source - a bottle, or “bus” converter.

A bottle electric generator is a closed housing with a rotating rubber roller on the outside, attached to the front fork. The housing contains the direct converting device – winding and magnets. The movement of the magnetic field is achieved by engaging the roller with the tire and directly transferring mechanical energy from the wheel to it. The higher the speed, the stronger the polarity inside the generator and the greater the voltage output.

"Bottle" is afraid of bicycle falls

Advantages of "bottles":

• the ability to disable it as unnecessary - just move the roller to the side;
• easy to install on any type of bike;
• inexpensive compared to sleeve generators.

Weaknesses include:

• weight imbalance: weight about 250 g, the “bottle” is attached to one side;
• low efficiency in wet weather - the roller slips over the tire;
• noise, high friction at speeds;
• tire sidewall wear;
• It takes a long time to adjust the tilt and position.

Separately, it is worth mentioning the carriage bicycle generator. Its body is fixed in the area of ​​the pedal assembly - the carriage, under the lower stays. The rotation of the magnetic device is set by a roller that is engaged with the rear wheel of the bike. The roller is secured to the tire by a clamping spring.

Contactless bicycle generator

The bottle and carriage generators produce electricity by contacting the moving wheel. The hub dynamo is a built-in element of the wheel. The contactless generator does not touch the wheel in any way and does not create friction forces or resistance to rotation. Eddy currents are formed due to the close proximity of the plane of rotation of the magnetized rim and a strong magnet.

The headlights are built directly into the device, electricity is transmitted directly through the rectifier bridge. The undeniable advantages of this generator include:

• no cables;
• there is no friction force or resistance from the device;
• light weight of the structure – no more than 60 g.

Non-contact energy sources can be safely used on road bikes for long journeys

The devices are attached in pairs: on the fork - the headlight, on the feather - the rear reflector. In fact, these are independent flashlights, only they do not work from batteries, but through the rotation of wheels in a magnetic field. The luminosity of the lamps is at the same level as or exceeds that of battery-powered lighting devices.

As the wheel slows down, the intensity of the eddy currents decreases, the lights should dim, and when the wheel stops, they should go out completely. To ensure uniform light and the ability to use the light even when parked, the design includes a capacitor (“battery” for generating electricity), which is filled when the bike moves.

How to make a generator with your own hands

Now let’s try to make a generator for a bicycle ourselves. We will use a stepper motor as a basis. To power the lighting devices you will need a motor with the following characteristics:

• rated current – ​​2.4 A;
• resistance – 1.2 Ohm;
• output voltage is 2.88 V.

The dynamo should be installed near the rear wheel hub. To transfer rotation from the wheel to the flywheel (rubberized wheel) of the motor, a transfer ring is required. To create it you will need flexible plastic tape. Manufacturing:

1. Twist the ribbons into a ring, welding the ends.
2. Cut mounting slots on the side for each wheel spoke. The depth of the slots is ¼ of the thickness of the ring.
3. Place the ring on the knitting needles, fill the slots with glue-sealant inside at each spoke.

When the ring is ready, a stepper motor is screwed to the free seats on the feathers, and the flywheel is installed on top of the ring. If there is no free space for the engine, you will need to weld an additional plate with holes onto the frame.

The general scheme for creating a generator with your own hands: generator - assembly of the electrical circuit (bridges, resistors, capacitors) - connection - installation of headlights.

To assemble the electrical unit for the headlights you will need:

• LEDs 1N4004 – 8 pcs (bridge converter);
• stabilizer LM317T;
• ceramic capacitor with a capacity of 1 μF;
• resistors 240 Ohm and 820 Ohm for the stabilizer;
• a 1W diode and a 110 Ohm resistor (0.25 W);
• wires;
• a plastic box where everything will be located.

We assemble the components taking into account the following diagram:

Another version of this scheme:

DIY electrical circuit

Assembly sequence:

1. Solder 1N4004 diodes into parallel bridges.
2. Solder a capacitor between the “positive” and “negative” ends of the circuit.
3. Install resistors and voltage stabilizer.
4. Solder the LED (1W) and resistor to the headlight circuit.
5. Connect the headlight to the capacitors through the wires, and then connect the electrical circuit to the generator. rear wheel.
6. To turn off the lamp even while riding a bicycle, install a switch in the gap between the capacitors that will close and open the circuit.

Homemade electric generator for the rear wheel of a bicycle

The housing with the electrical circuit is fixed on the bicycle frame, the wires are secured with clamps.

On last stage the operation of the system is checked: the wheel should move freely along the wheel and move synchronously with it. With a correctly assembled electrical circuit of capacitors, resistors and rectifier bridges, the headlight will turn on. True, at low wheel speeds its light will flicker.

Conclusion

An electric generator will allow you to extract additional benefits from pedaling - receiving absolutely “free” energy to illuminate your two-wheeled vehicle when driving along a dark highway or rough terrain. Small and useful, this device requires virtually no maintenance and can easily be assembled yourself.

Hello, dear comrades! I bring to your attention an environmentally friendly source of electricity.
Due to the nature of my work, I have repeatedly had to solve problems of energy supply to remote objects. However, the methods used are not acceptable to me for financial reasons. What remains is experience.
When planning the backup power supply for my “facility”, I proceeded from the technical and financial possibilities available to me: when the electricity runs out in one feeder, I switch to another (ATS), the entire external network will shut down - there is a gasoline generator, the fuel will run out (well, or to save it) - solar panels. As a reserve - 6 pieces of assorted batteries from cars (“passport” capacity from 44 to 115 Ah). Their capacity, of course, is not the same as in their youth, but for small loads they are quite suitable (I also use it as a starting battery for resuscitation of frozen cars).
The minimum total power of consumers in winter is 100 W (boiler automation, circulation pump and 2-3 LED lamps). In the event of an acute shortage of gasoline, I will not be able to provide so much with the grace of the sun alone (short winter day + snow). Well, or you need to increase the area of ​​​​solar panels (a rather expensive pleasure).
The idea of ​​​​creating a simple backup source of electricity “from what is at hand” has been around for a long time. I don’t think it’s wise to invest a lot of money, by my standards, into something that may never be needed.
So we have: used car batteries in an assortment, a used 80A generator (from dozens of VAZs, changed at the time for a more powerful one), my son’s bicycle. And legs. Well, and of course, hands.


My son made a stand for the rear wheel from pieces of plywood. The rear wheel axle nuts were replaced with “pegs” (foot supports, used when performing cycling stunts). Using pieces of metal profile and M8 studs, we secured the generator to the rear wheel. We connected the battery and started charging it.


Yeah! Right now! There is not enough strength. I started to figure it out and count. The relay-regulator keeps (it tries) 14.5 V, the battery charging current is 4-5A. Total more than 70 W. Taking into account the losses of the pedal-chain-tire-pulley, you probably need the same amount more. Vicki reports that this is unrealistic - I have never been an athlete.
We need to somehow reduce the power. The charging current depends on the design (size) of the battery, you can’t change anything here - we use what we have. The tension remains. I remember that motorcycles had 6 volts. You can remove 6 volts from a 12-volt generator by using a suitable voltage relay instead of a standard car one. And charge a 12-volt battery in two passes, “dividing” it in half. This will halve the effort on the pedals by doubling the time they rotate.
In the battery I used, the jumper between the third and fourth banks is located just under the plug (if you remember before, the jumpers were on the outside, now I’ve only seen them on trucks). I found a 100-mm self-tapping screw, stained with silicone (I cleaned the nose of the gun). Silicone protects the iron self-tapping screw from acid, or rather, on the contrary, electrolyte from foreign iron. Slowly, carefully, with force, I screwed it into the jumper (the main thing here is not to overdo it and not to twist it all the way through - you can short the plates in this jar) and got the third contact. We must remember that it is positive if it is paired with a standard “minus” and negative if it is paired with a native “plus”.


I converted the standard relay-regulator into a simple brush assembly (I bit off the relay legs, soldered the wires), installed PP1 from IZhak and the process began! The motorcycle relay kept the voltage no higher than 7.5 V (average approx. 7 V), average charge current approx. 4 A. The effort on the pedals is normal, for my untrained body. In general, everything works.
However, as we were taught in ML philosophy classes: practice is the criterion of truth! It is necessary to evaluate the practical value of this energy source. The following assessment methodology was proposed: the control battery is connected to the emergency lighting until the latter goes out. After this, the battery is charged using a pedal for one hour and reconnected to the lighting. The ratio of charging time to lighting operating time can be a parameter for assessing the efficiency of the system.


Emergency lighting system - LED strips (left over from apartment renovation) with a total length of 5.7 m, glued to the crane beam guide. Operating voltage from 12.5 V to 8 V (average 10 V), current 0.8 A. Average power consumption 8 W. If we assume that from the generated power of 28 W (7 V * 4 A) we can “store” 20 W, the expected operating time of the emergency lighting system is approx. 2.5 hours.
The previously discharged battery (to 7.5 V under load with an LED strip) was charged for 40 minutes. My son and I took turns pedaling for 5 minutes - it turned out to be not an easy task. 20 minutes for one half of the battery and 20 minutes for the other.


Then they connected the emergency lighting to it and began to wait. Here I was met with bitter disappointment - my calculations turned out to be wrong. After two and a half hours we went home, leaving the LEDs on. In the morning, 12 hours later, I went to check - they were glowing, they were infected. After another 8 hours there was almost no light - the voltage under load dropped to 7.5 V.
In general, after 40 minutes of recharging with the bike generator, the operating time was about 20 hours. I made a mistake somewhere  But the main thing is that the result was achieved. Having such a device, you can provide yourself with electricity sufficient for modest lighting and operation of not very powerful devices. An hour on an exercise bike – a day with light
Practical advice for those wishing to repeat the experience:
A bike with gear shifting is highly desirable - you'll start at one speed and finish at another.
Swap the tires on the wheels. The rear tire has a developed tread on which the generator pulley bounces, constantly bounces and loses drive.
Do not use a semiconductor relay-regulator - the field winding of a car generator is designed for higher power than the output stage of a motorcycle relay. This is how I burned the relay from Java.

It is necessary to monitor the charging process using a voltmeter (for example, at least 6.5-7 V), an ammeter (± current) or a control light (some relays allow you to install it).
If you stop to rest, remove the terminal from the battery; the discharge through the relay with the generator will quickly consume your work.

Motor generator located on the left of the circuit, the output voltage (+/-12 V) is on the right. You can connect any load to the output: light bulbs, fluorescent lamps, LED lighting equipment, radio, portable charger for a mobile phone, TV, satellite receiver, inverter. All connected devices must be rated for 12 V.

Let's look at the diagram in more detail. Bicycle The generator produces 3-phase alternating current, which must be converted to direct current before use. A three-phase rectifier can be made from six diodes or purchased ready-made (used in wind energy). It looks like a regular bridge rectifier, only it has five terminals instead of four. The rectifier must be rated at least 100 V and 35 A. Each of the diodes must withstand the same voltage, but only half the current (20 A). The straightener requires some cooling - so attach it to a large metal piece.

The output power of the rectifier cannot be directly supplied to a light bulb or TV, since pedaling does not produce a stable voltage. It will fluctuate between zero and maximum and may damage the equipment. This problem is solved by connecting the battery in parallel to the output of the rectifier, which will absorb the excess power generated by the generator and fill the time intervals when the generator does not produce enough power or even stops at short time. The battery does not have to be large or anything special - any lead-acid battery will do. If it has a large capacity, that's also good. You can use an old 12V 16Ah computer UPS battery. For home use, sealed batteries that do not emit gases are recommended.

There are other components in the diagram. One of them is a fuse, which is needed in case of a short circuit. The battery produces so much current that it can even ignite the cable. A 2.5 mm2 cable and a 30 A fuse are recommended. There are also two meters on the diagram (not in the photo). One voltmeter (with its own fuse) and one ammeter. Despite the fact that the pedal generator works without them, a voltmeter is highly recommended for the sake of battery health. It's better to take a digital voltmeter. As soon as it displays 14 V (for 12 V systems), you need to stop rotating the pedals. Never exceed 15 V. The voltage should also not fall below 10.5 V. The analog ammeter (with a zero mark in the middle of the scale) is not very important, but it shows whether energy is being pumped into the battery (eventually leading to a full charge of the battery) or consumption ( leading to battery discharge). The circuit cannot use a digital ammeter because the current changes too frequently to provide a consistent reading. The range of the ammeter depends on the current drawn by the load. It is best to buy one with a range of +/- 20 A.