E-bike - accessibility and efficiency on a personal example
Recently, articles about electric bikes announced by large companies or laid out on kickstarters and analogues have been skipping on Giktayms. But they all share one thing - low efficiency and repeatedly inflated price. For example, the Xiaomi Mi Q Bike Folding Electric Bicycle travels up to 45 km in ideal conditions at a speed of 20 km / h. Why at this speed in general the motor? But with an increase in speed every 10 km / h increase the flow, roughly speaking, twice. Yes, it is also necessary to take into account the fact that the more power we take from the battery, the less capacity it will give. We draw conclusions about the range.
About how I got to electric transport and at what price - under the cut.
Bought at one time ashanbayk with the proud name "Racer" for 8 thousand rubles. I bought it consciously, chose the best of the worst, spent three days fine-tuning the device and got a very good bike for cheap. I skated on it to the village and back with much greater efficiency than I used to have on the “Ural” and was happy. I note that at the time of the “Ural” there was still a moped, in which the piston would be erased, the carburetor should be cleaned, then the sugar in the tank ... In general, I suffered with it, suffered and back to the “Ural” because the bike is safer. Then came the work. I immediately realized that riding a bicycle outside the city for work is good, but on arrival you find yourself tired, sweaty, and do not work at all. Therefore, the question of the electrification of the bicycle moved from the stage “that would be cool” to the “urgently necessary!” Stage, and I began to act.
At one forum on electric vehicles, which is the first link in Google, I got the theory. The theory is such that motors for a bicycle are at least three types: gearbox, direct drive and outboard.
')
Geared motor-wheel. It consists of, in fact, a motor and a planetary gearbox, usually with a transmission of 5 to 1. It differs from a direct drive with a lower weight (1.5 - 5 kg) and a large torque, all other things being equal. Suitable for hilly terrain and bad roads. It has a frivil that allows you to go forward and pedal no worse than with a regular bicycle wheel.
Direct drive motor wheel. The stator with the coils is rigidly connected with the axis, the rotor with the magnets with the rest of the wheel, nothing else. More resource than the gear, because of rubbing only two bearings. Great efficiency and speed, but a lot of weight (7 - 10kg) and less torque than the gear. Great for smooth roads and high speeds. Allows recovery (battery charging due to braking). Riding on the pedals is complicated by the fact that the motor-wheel while working as a generator, taking away some of the energy on themselves.
Outboard motor. Mounted under the carriage, the torque is transmitted to the leading star through frivil. Installation is more complicated than the previous ones. The highest efficiency due to the use of a bicycle transmission, but at the cost of increased wear of the latter. Suitable for absolutely everything.
Motor-wheels are installed instead of the usual wheel by a simple replacement; they are front under 100mm and rear under 135mm with thread for ratchet. There are also under the tape, but rarely. Powerful motor wheels can break the dropouts with torque, especially on the fork, so be sure to install dropouts amplifiers. For low-power motor wheels, this is not necessary, but desirable. I did not put a 350W motor.
To control the motor, you need a controller, which are also different not only in power. An electric motor has an interesting feature - the speed sets the voltage, and the torque - the current. That allows, changing these parameters in the controller, to achieve with the same consumption from the battery as high speed and high traction, depending on the situation. All that is engaged in CAT (or rather, it is closer to the variator) in the case of the engine. Some controllers control the voltage, that is, the gas handle controls the speed from zero to maximum, and the current is automatically selected to achieve this speed. Useful in the mud, where constant speed with high torque is needed. Others are controlled by current, that is to say, you control the gas with the handle of the gas, but the speed is always maximum (at idle). Allows you to control the power. Also on consumption distinguish battery and phase current. Battery current is the current drawn from the battery, respectively. Phase - going to the motor, its three phases (as a rule, although there are motors with a different number of phases, but this is a bench exotic). It is useful to limit the latter, since, for example, 500W can be either 50V 10A or 5V 100A, and not every winding 100A can survive for a long time, but not all controllers can.
The most expensive part is the battery. Some start with lead batteries, usually from UPS, because it is cheaper for a piece. But, one way or another, everyone comes to lithium, because the more currents given away, the resource and noticeably less mass, because of which the pleasure of skating is more and the cost of operation is sometimes less, at least for a piece and much more expensive. And here begins a great variety. On the market there are many types of lithium batteries of different chemicals and manufacturers, and therefore quality. The most popular are lithium-ion and lithium-polymer because of the price and low weight. But there is a risk of fire during breakdown or overcharge. The consequences are sad, but spontaneous inflammation cases are rare. Resource of the order of 500-800 charge-discharge cycles. Li-zhelezofosfatnye or LiFePO4 are considered the most reliable because they are not afraid of frost down to -30 ° C, have a resource of about 2000 cycles, the greatest current output and do not burn at all. But among lithium the most difficult and expensive. Also popular are the so-called "folk cutlets", which are model batteries, the only advantage of which is the price. But the advantage is so significant that sometimes you think about it. A resource of about 100 cycles, often swell, but with proper control and some luck in quality can live quite a long time.
I ordered a set from one of the members of the forum. It turned out 1030 yuan per set, consisting of 36V 350W gear motor-wheel, controller, spokes, rims, brake handles with pressure sensors and gas knob. Battery 48v 12Ach type "frog" cost 1615 yuan. 9rub for 1 yuan at the time of purchase, that is 24 thousand rubles. for all or 32 thousand rubles. for everything, including the bike. This is the main minimum. However, you can buy everything in many places, including on any aliexpress with ebay. If we consider different additions such as a wattmeter, a trunk or a pneumatic hearth, then the cost easily passes over fifty, but this is all optional and can be installed with the same success on an ordinary bicycle. Well, except that, except for the wattmeter, which I strongly advise, because it shows voltage, current, power, current and spent, which allows to judge about the discharge of the battery more clearly than any indicators of charge and overall motion efficiency.
Assembling labor is not, everything is connected according to logic, in accordance with connectors and colors. However, the Chinese colors do not always match. In this case, the method of scientific spear is used, preferably first with a multimeter. Included are brake handles with pressure sensors. It is highly desirable because they turn off the motor when braking. If there are hydraulic brakes on the donor bike or some tricky handles that you don’t want to change, then sensors should be stuck to them (even reed switches, even mikriks, even though hall sensors).
After the assembly turned out such a device:
(Photos presented in the form of cross stereopairs. How to look at them read here . Who can not or does not want to view them in the form of three-dimensional images, can look like ordinary pictures, and such stereo pairs are beautiful)
Weight 27 kg. No problem enters the 5th floor without elevator. This unit runs up to 42km / h in a straight, flat road without wind relative to the ground. If you hold the throttle in one position for a few seconds, the cruise control turns on, after which the handle can be released and the bike will go at a given speed. Cruise is disconnected by the handle of gas or brake handles. When sneaker on the floor and with pedals enough to the village and back, 40km and a little more remains. But with such a load, the battery gives only 400-450Wh of energy from its 590Wh. If you drive 30 km / h, then the consumption will decrease by about two times and the battery will give up more due to a smaller load, respectively, the range will be more than 80 km. And if you go 20km / h?
Console mount battery refused to serve faithfully on a rigid frame on our roads, bursting the most arrogant way. I had to think about where to place the battery. On the trunk maneuverability suffers, because the rear is overloaded. Maneuverability is higher in the backpack on the back, but the back is opposite and the chance to fly over the steering wheel when braking is due to the high center of gravity. Currently, everything is placed in bags in a triangle frame.
For safety, I made a brake light from a katafot and red 50dm cmd format LEDs.
It is controlled by the ATtiny13 microcontroller via the mosfets. A microcontroller with a mosfet is built into the charging case from a once-flying nephew helicopter; it takes power from a regular usb-charge, which feels good under 48V power conditions. By the way, the majority of similar charge and power supplies normally work from 48V.
When power is applied, the microcontroller turns on the stop signal with a shim for a quarter of the power, and when the brake knobs are pressed (+ 5V disappears from them at the input to the motor controller) it turns on full.
The electric bike is used for the second season, a bunch of battery-controller-motor work without degrading performance and the need for repairs. At the first trips was a curious impression. The motor in motion is not felt from the word “absolutely” and, in combination with the cruise control, creates the illusion that you are spinning the 42km / h. But when the motor is turned off, the load on the legs increases and the whole illusion dissipates. Now I'm used to it, and the trips have become quite common, and the dynamics and reliability do not have to go to the engine, which I advise you.
About how I got to electric transport and at what price - under the cut.
Bought at one time ashanbayk with the proud name "Racer" for 8 thousand rubles. I bought it consciously, chose the best of the worst, spent three days fine-tuning the device and got a very good bike for cheap. I skated on it to the village and back with much greater efficiency than I used to have on the “Ural” and was happy. I note that at the time of the “Ural” there was still a moped, in which the piston would be erased, the carburetor should be cleaned, then the sugar in the tank ... In general, I suffered with it, suffered and back to the “Ural” because the bike is safer. Then came the work. I immediately realized that riding a bicycle outside the city for work is good, but on arrival you find yourself tired, sweaty, and do not work at all. Therefore, the question of the electrification of the bicycle moved from the stage “that would be cool” to the “urgently necessary!” Stage, and I began to act.
At one forum on electric vehicles, which is the first link in Google, I got the theory. The theory is such that motors for a bicycle are at least three types: gearbox, direct drive and outboard.
')
Geared motor-wheel. It consists of, in fact, a motor and a planetary gearbox, usually with a transmission of 5 to 1. It differs from a direct drive with a lower weight (1.5 - 5 kg) and a large torque, all other things being equal. Suitable for hilly terrain and bad roads. It has a frivil that allows you to go forward and pedal no worse than with a regular bicycle wheel.
Direct drive motor wheel. The stator with the coils is rigidly connected with the axis, the rotor with the magnets with the rest of the wheel, nothing else. More resource than the gear, because of rubbing only two bearings. Great efficiency and speed, but a lot of weight (7 - 10kg) and less torque than the gear. Great for smooth roads and high speeds. Allows recovery (battery charging due to braking). Riding on the pedals is complicated by the fact that the motor-wheel while working as a generator, taking away some of the energy on themselves.
Outboard motor. Mounted under the carriage, the torque is transmitted to the leading star through frivil. Installation is more complicated than the previous ones. The highest efficiency due to the use of a bicycle transmission, but at the cost of increased wear of the latter. Suitable for absolutely everything.
Motor-wheels are installed instead of the usual wheel by a simple replacement; they are front under 100mm and rear under 135mm with thread for ratchet. There are also under the tape, but rarely. Powerful motor wheels can break the dropouts with torque, especially on the fork, so be sure to install dropouts amplifiers. For low-power motor wheels, this is not necessary, but desirable. I did not put a 350W motor.
To control the motor, you need a controller, which are also different not only in power. An electric motor has an interesting feature - the speed sets the voltage, and the torque - the current. That allows, changing these parameters in the controller, to achieve with the same consumption from the battery as high speed and high traction, depending on the situation. All that is engaged in CAT (or rather, it is closer to the variator) in the case of the engine. Some controllers control the voltage, that is, the gas handle controls the speed from zero to maximum, and the current is automatically selected to achieve this speed. Useful in the mud, where constant speed with high torque is needed. Others are controlled by current, that is to say, you control the gas with the handle of the gas, but the speed is always maximum (at idle). Allows you to control the power. Also on consumption distinguish battery and phase current. Battery current is the current drawn from the battery, respectively. Phase - going to the motor, its three phases (as a rule, although there are motors with a different number of phases, but this is a bench exotic). It is useful to limit the latter, since, for example, 500W can be either 50V 10A or 5V 100A, and not every winding 100A can survive for a long time, but not all controllers can.
My controller
The most expensive part is the battery. Some start with lead batteries, usually from UPS, because it is cheaper for a piece. But, one way or another, everyone comes to lithium, because the more currents given away, the resource and noticeably less mass, because of which the pleasure of skating is more and the cost of operation is sometimes less, at least for a piece and much more expensive. And here begins a great variety. On the market there are many types of lithium batteries of different chemicals and manufacturers, and therefore quality. The most popular are lithium-ion and lithium-polymer because of the price and low weight. But there is a risk of fire during breakdown or overcharge. The consequences are sad, but spontaneous inflammation cases are rare. Resource of the order of 500-800 charge-discharge cycles. Li-zhelezofosfatnye or LiFePO4 are considered the most reliable because they are not afraid of frost down to -30 ° C, have a resource of about 2000 cycles, the greatest current output and do not burn at all. But among lithium the most difficult and expensive. Also popular are the so-called "folk cutlets", which are model batteries, the only advantage of which is the price. But the advantage is so significant that sometimes you think about it. A resource of about 100 cycles, often swell, but with proper control and some luck in quality can live quite a long time.
I ordered a set from one of the members of the forum. It turned out 1030 yuan per set, consisting of 36V 350W gear motor-wheel, controller, spokes, rims, brake handles with pressure sensors and gas knob. Battery 48v 12Ach type "frog" cost 1615 yuan. 9rub for 1 yuan at the time of purchase, that is 24 thousand rubles. for all or 32 thousand rubles. for everything, including the bike. This is the main minimum. However, you can buy everything in many places, including on any aliexpress with ebay. If we consider different additions such as a wattmeter, a trunk or a pneumatic hearth, then the cost easily passes over fifty, but this is all optional and can be installed with the same success on an ordinary bicycle. Well, except that, except for the wattmeter, which I strongly advise, because it shows voltage, current, power, current and spent, which allows to judge about the discharge of the battery more clearly than any indicators of charge and overall motion efficiency.
Assembling labor is not, everything is connected according to logic, in accordance with connectors and colors. However, the Chinese colors do not always match. In this case, the method of scientific spear is used, preferably first with a multimeter. Included are brake handles with pressure sensors. It is highly desirable because they turn off the motor when braking. If there are hydraulic brakes on the donor bike or some tricky handles that you don’t want to change, then sensors should be stuck to them (even reed switches, even mikriks, even though hall sensors).
After the assembly turned out such a device:
(Photos presented in the form of cross stereopairs. How to look at them read here . Who can not or does not want to view them in the form of three-dimensional images, can look like ordinary pictures, and such stereo pairs are beautiful)
Watch
Weight 27 kg. No problem enters the 5th floor without elevator. This unit runs up to 42km / h in a straight, flat road without wind relative to the ground. If you hold the throttle in one position for a few seconds, the cruise control turns on, after which the handle can be released and the bike will go at a given speed. Cruise is disconnected by the handle of gas or brake handles. When sneaker on the floor and with pedals enough to the village and back, 40km and a little more remains. But with such a load, the battery gives only 400-450Wh of energy from its 590Wh. If you drive 30 km / h, then the consumption will decrease by about two times and the battery will give up more due to a smaller load, respectively, the range will be more than 80 km. And if you go 20km / h?
Console mount battery refused to serve faithfully on a rigid frame on our roads, bursting the most arrogant way. I had to think about where to place the battery. On the trunk maneuverability suffers, because the rear is overloaded. Maneuverability is higher in the backpack on the back, but the back is opposite and the chance to fly over the steering wheel when braking is due to the high center of gravity. Currently, everything is placed in bags in a triangle frame.
The current look:
For safety, I made a brake light from a katafot and red 50dm cmd format LEDs.
Watch
It is controlled by the ATtiny13 microcontroller via the mosfets. A microcontroller with a mosfet is built into the charging case from a once-flying nephew helicopter; it takes power from a regular usb-charge, which feels good under 48V power conditions. By the way, the majority of similar charge and power supplies normally work from 48V.
Watch
When power is applied, the microcontroller turns on the stop signal with a shim for a quarter of the power, and when the brake knobs are pressed (+ 5V disappears from them at the input to the motor controller) it turns on full.
The electric bike is used for the second season, a bunch of battery-controller-motor work without degrading performance and the need for repairs. At the first trips was a curious impression. The motor in motion is not felt from the word “absolutely” and, in combination with the cruise control, creates the illusion that you are spinning the 42km / h. But when the motor is turned off, the load on the legs increases and the whole illusion dissipates. Now I'm used to it, and the trips have become quite common, and the dynamics and reliability do not have to go to the engine, which I advise you.
Source: https://habr.com/ru/post/395653/
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