Electric current speed
Let’s do this thought experiment. Imagine that there is a certain village at a distance of 100 kilometers from the city, and that a wire signal line about 100 kilometers long with a light bulb at the end is laid from the city to this village. Two-wire shielded line, it is laid on supports along the road. And if you now send a signal along this line from city to village, then after what time will it be received there?
Calculations and experience tell us that a signal in the form of an illuminated light bulb will appear at the other end in at least 100/300000 seconds, that is, in at least 333.3 μs (without taking into account the inductance of the wire) a light will light up in the village, which means that a current will be established in the conductor (for example, we use direct current from a charged capacitor).
100 is the length of each of the veins of our wire in kilometers, and 300,000 kilometers per second is the speed of light. the speed of propagation of an electromagnetic wave in a vacuum. Yes, the “motion of electrons” will propagate along the conductor at the speed of light.
But the fact that electrons begin to move one after another at the speed of light does not mean at all that the electrons themselves move in the conductor at such a tremendous speed. Electrons or ions, in a metal conductor, in an electrolyte or in another conducting medium, cannot move as fast, that is, charge carriers do not move relative to each other at the speed of light.
The speed of light in this case is the speed with which the charge carriers in the conductor begin to move one after another, that is, this is the speed of propagation of the translational motion of charge carriers. The charge carriers themselves have a “drift velocity” at a steady current, say in a copper conductor, only a few millimeters per second!
Let us explain this point. Let’s say we have a charged capacitor, and we connect long wires to it from our light bulb, installed in a village at a distance of 100 kilometers from the capacitor. Connecting wires, that is, closing the circuit, we carry out the switch manually.
What will happen? When the switch is closed, charged particles begin to move in those parts of the wires that are connected to the capacitor. Electrons leave the negative plate of the capacitor, the electric field in the dielectric of the capacitor decreases, the positive charge of the opposite (plus) plate decreases. electrons from the connected wire run into it.
So the potential difference between the plates decreases. And since the electrons in the wires adjacent to the capacitor began to move, other electrons from distant places of the wire come to their places, in other words, the process of redistribution of electrons in the wire begins due to the action of the electric field in a closed circuit. This process spreads further and further along the wire and finally reaches the filament of the signal lamp.
So, the change in the electric field propagates along the conductor at the speed of light, activating the electrons in the circuit. But the electrons themselves move much slower.
Before we go any further, consider a hydraulic analogy. Let mineral water flow from the village to the city through a pipe. In the morning, a pump was started in the village, and he began to increase the pressure of the water in the pipe to force water from the village source to move into the city. The pressure change spreads through the pipeline very quickly, at about a speed of 1400 km / s (depends on the density of water, on its temperature, on the magnitude of pressure).
A split second after starting the pump in the village, the water began to move in the city. But is this the same water that is currently moving in the village? No! The water molecules in our example push each other, and they themselves move much more slowly, since the speed of their drift depends on the magnitude of the pressure. The crush of molecules among themselves spreads many orders of magnitude faster than the movement of molecules along a pipe.
So it is with an electric current: the speed of propagation of an electric field is similar to the propagation of pressure, and the speed of movement of electrons that form a current is similar to the movement of water molecules directly.
Now let’s return directly to electrons. The speed of the ordered movement of electrons (or other charge carriers) is called the drift speed. Its electrons acquire due to the action of an external electric field.
If there is no external electric field, then the electrons move chaotically inside the conductor only in thermal motion, but there is no directed current, and therefore the drift velocity on average turns out to be zero.
If an external electric field is applied to a conductor, then depending on the material of the conductor, on the mass and charge of charge carriers, on temperature, on the potential difference. charge carriers will start moving, but the speed of this movement will be significantly less than the speed of light, about 0.5 mm per second (for a copper conductor with a cross section of 1 mm2, through which a current of 10 A flows, the average drift velocity of electrons will be 0.6–6 mm / c).
This speed depends on the concentration of free charge carriers in the conductor n, on the cross-sectional area of the conductor S, on the particle charge e, on the magnitude of the current I. As you can see, despite the fact that the electric current (front of the electromagnetic wave) propagates along the conductor at the speed of light, the electrons themselves move much more slowly. It turns out that the speed of the current is a very low speed.
Electric scooter speed: what happens and what depends on?
The scooter has been considered the preserve of children and adolescents for decades. With the emergence and development of electric scooter models, amid growing concern for the environment in the form of abandoning private cars and even public transport in favor of eco-friendly bicycles and electric scooters, this two-wheeled iron horse gradually became a popular means of getting to work.
Of course, this is a purely urban vehicle, and you can’t go too far on it without recharging, but sometimes you have to wind many kilometers even around the city, and you want to spend as little time as possible on it. In addition, fans of fast driving are ready to test almost anything as a racing mechanism, therefore many people are interested in how much this unit accelerates.
Unfortunately, there is no officially recognized speed record for an electric scooter, if only because an ordinary unit of this type is not equipped with a speedometer. In addition, manufacturers usually do not strive to create a truly fast electronic assembly, and they have two good reasons for this.
- Danger to the passenger. It is difficult to come up with such a form of transport, on which the rider would be even less protected than on a scooter. The maximum that can be thought of for safety is the minimum “set of a cyclist” made of a helmet and elbow pads with knee pads, but at high speed they will certainly not save you from injury. In addition, a scooter with a motor, unlike the same bike, is noticeably more difficult to control on steep turns, therefore manufacturers prefer to set a relatively low maximum speed for the device.
- Increase in mass with increasing speed. An ordinary mechanical scooter is quite light transport, it is convenient to overcome obstacles and move up stairs with it, but in the electric version the battery is a priori the heaviest part. Unfortunately, in most cases there is a direct relationship between the battery capacity and the power supplied by the motor, and the latter determines how well the vehicle picks up speed. Accordingly, the existing high-speed models weigh quite a lot and are therefore inconvenient, but you can make them even faster, but then they will become completely inconvenient.
However, in our country there are enough folk craftsmen who want to remove the software speed limit and increase it through some modernization of the device, thanks to which more serious 80 and 90 km / h are already achieved. An unofficial record and generally recognized benchmark for each modernized scooter can be considered 100 km / h, but the owner can accelerate so much only if he 100% trusts both the quality of the road, which should be perfectly flat, and his ability to drive a vehicle in such conditions.
What factors affect the maximum speed of a scooter?
The concept of the maximum speed for a particular model is somewhat arbitrary. usually it means the average maximum speed, which is relatively easy to achieve, but it happens that the manufacturer deliberately overestimates the numbers, and the declared maximum can be achieved only under ideal conditions. To understand how to squeeze everything out of an electric scooter, let’s consider what the speed of movement depends on.
- Motor characteristics. This is almost the main criterion, which is one of two consistently affecting speed. Power and torque are the reserve of transport power, they do not change under any circumstances (except for modernization with the replacement of parts). Expecting to drive as fast as possible, in any case, you should pay attention to those models that have the best indicators of these characteristics.
- Wheel diameter. The engine spins the wheels up to a certain number of revolutions per second. It is clear that a scooter with small wheels will have a shorter distance covered than a model with a larger diameter. Of course, the larger the wheels, the heavier they are, and the more difficult it is to rotate them, however, the factory manufacturer usually takes this moment into account and makes the engine power appropriate.
- Vehicle and passenger weight. The total mass of a moving vehicle greatly affects the speed of movement. if it is high, the friction force with the road surface increases, and you will not go so fast. A fast electric scooter should be light on its own, without losing the rest of the ride.
- Features of the road surface. If the road is perfectly smooth, the scooter literally slides along it without experiencing much resistance, and this, of course, is a huge plus for transport. Whether the case is a viscous coating, which allows for some subsidence of the scooter and the wheels sticking in at least minimal holes formed under its own weight. In addition, the slope also matters. as it is much harder to go uphill than downhill, so the electric motor will spend much more effort when climbing.
- Headwind. Even this seemingly insignificant factor affects speed as it creates additional drag. By itself, it is usually not as powerful, but coupled with imperfect road surface and climbing uphill, the result can be depressing for someone in a hurry.
What speed is needed?
The reasons why manufacturers do not produce truly racing scooters have been described above. it remains to understand how to choose a specific model for their tasks, because even the declared 60 km / h is quite a lot for short trips around the city. There is a special classification of electric scooters in the context of who is driving. it also contains information about the normal power of such a vehicle. Experts advise the following.
- Children. It is generally accepted that 5-10 km / h is the ceiling for them. In fact, this is an adult’s walking or a leisurely run, but for a student who is just learning, more is definitely not needed. For such an indicator, a motor with a power of about 100 W is enough.
- Teenagers and adult beginners. For both of them, requests may be more serious than simple “pokatushki” around the yard. for them this is already an option for personal transport. At the same time, such drivers usually lack experience and endurance, because a speed above 15 km / h is not necessary for them, which in watt terms is 150-250 W.
- For adults for everyday life. If you do not surprise you with a scooter, and you need an electric scooter every day, since it replaces a car or public transport, focus on the speed barrier of about 35 km / h. after all, you need not just go to the same job, but hurry. You can expect such agility from a 250-350 W model.
- Racers. If you consider yourself a lover of fast driving and are not simply afraid to accelerate such a fragile structure to such speed, you should pay attention to models that can accelerate to 40-60 km / h. In such scooters, manufacturers often emphasize that they do not lose their cruising speed even in adverse conditions, and therefore their power is impressive. usually it is from 700 to a mind-blowing 2000 watts.
How to upgrade a vehicle?
No matter how hard you try to choose the most advanced electric scooter, it is very likely that the declared characteristics are somewhat exaggerated. For example, with a power reserve of 90 km, the battery is really only enough for 60-70 km, the unit does not necessarily reach the maximum speed at least 2-3 km / h, and with a half-discharged battery, problems begin in any driving mode.
To increase the “endurance” of the scooter, you must purchase and install a more powerful battery for it. The difficulty lies in the fact that many models have individual dimensions, and it is extremely difficult to find a model of the same capacity, but the same dimensions. It is good if the configuration of the case involves the installation of additional batteries in special cells. in this case it will be much easier to experiment.
As for the engine, in almost all cases it will normally survive an acceleration of about 1.5 or even 2 times higher than the factory standard, especially if you don’t mock your homemade product, riding it uphill on rubble and in the opposite wind. Another thing is that the wheel motor controller has certain limitations, which do not allow the scooter to accelerate more than the “normal” speed set by the factory. Therefore, the essence of the modification is either to replace the controller with another, or you will have to thoroughly re-solder the original board.
You will learn more about the speed of an electric scooter by watching the following video.
Electric scooter for the city: testing the Ninebot KickScooter E22
The 300W Ninebot KickScooter E22 engine is capable of accelerating to 20 km / h (during the test, by the way, the scooter gave out 21 km / h), which for driving on the sides of city highways, sidewalks or specialized paths (which, unfortunately, are far from everywhere) will be enough. It is worth clarifying right away that in order to reach the maximum speed, before the first race, you will need to activate the scooter in the Segway-Ninebot proprietary application. You just register, connect the scooter to your phone via Bluetooth (you may still need to update the firmware, but this will take a couple of minutes) and you can ride. After that, the Ninebot KickScooter E22 will be able to rush you around the city without any restrictions.
Large power reserve
The battery capacity of the electric scooter is 216 Watt-hours, which is equivalent to 22 kilometers of autonomous driving. In principle, these indicators are enough to get to work in the morning and back home in the evening on one battery charge.
Even if your place of permanent deployment is more than a dozen kilometers from the office and you are worried that the ninebot will not withstand the return journey, you can just take a charger with you. I am glad that it is very compact and will not squeeze things in your backpack.
But this may not be necessary either, since the Ninebot KickScooter E22 has 3 riding modes:
- energy saving (lower speed at long distances);
- standard (recommended speed 20 km / h);
- sporty (maximum speed up to 22 km / h).
In total, when combining these modes, you can get up to 45 kilometers of autonomous travel. Also, this scooter is equipped with the updated Smart-BMS battery management system, which maintains an optimal charge mode, protects the battery from overcharge / overdischarge / overload and allows you to extend its life.
Good cross-country ability
Thanks to its high ground clearance and massive 9-inch wheels, the ninebot feels confident enough on broken asphalt and other surfaces that were once a road. Pits, potholes and other irregularities do not make you jump and lose control, since the scooter has quite good shock absorption.
The Ninebot KickScooter E22 also handles small tiles well, with little to no vibrations when driving at seams. The engine has enough power to successfully overcome inclines up to 15 degrees. Not to mention the ramps and other slopes that the scooter just flies by. And this is with a 90 kilogram person on board (by the way, the maximum permissible load is 100 kilograms). It is also worth noting the softness with which the scooter enters corners, almost without losing speed.
With this indicator, the electric scooter is also all right. It is equipped with two brakes: one mechanical over the rear wheel and the other electric on the steering wheel, which is activated by pressing a lever. The front one is intended, rather, for emergency braking, as it is rather harsh. But it practically guarantees that you will not run over someone inadvertently.
The Ninebot KickScooter E22 also has a useful function for setting the minimum speed at which the electric drive is activated. You can set the indicator from 0 to 5 km / h and either start, as they say, from a place or first push off with your foot, and then step on the gas. as it is convenient.
But the reliability of the scooter does not end with only driving characteristics. The frame is made of lightweight and durable aircraft-grade aluminum alloy, and the handlebars are fixed to the column with 6 bolts that can be easily screwed in with the included hexagon.
You shouldn’t worry about the visibility of the scooter at night either: there are two brake lights on the sides at the rear, and a powerful, but not dazzling reflector with a 13.5-meter visibility zone in front. Also included is a mechanical bell, loud enough to announce the arrival of yawning passers-by.
It would seem, what functions can an electric scooter have, in addition to the main one? Ninebot KickScooter E22 is quite a technological thing. On the steering column, it has a digital display showing the current speed and battery capacity, as well as pairing with the phone in the app. Here you can also set up lighting effects (continuous glow of the headlight or periodic flickering).
In the program itself, you can block the wheels of the ninbot if you leave it on the street unattended, and also select driving modes. For example, there is a quite attractive cruise control mode that turns on on the smartphone screen and is activated when you press the throttle for 5 seconds continuously. Great feature for straight routes without sharp turns.
Also noteworthy is the recirculation of energy when braking using the front brake. By blocking the electric impulse in the front wheel, the braking distance is only 5 meters (at maximum speed), and the energy of this impulse does not disappear without a trace, but returns to the battery. In physics, this is called recuperation.
Ease of use
In addition to the thoughtful technological filling, the Ninebot KickScooter E22 boasts good ergonomic performance. The aluminum foldable design allows you to carry the scooter by hand without much hassle. After all, the weight of the product is only 13.2 kilograms, which is lighter than many brothers from the electric scooter family.
Also, the dimensions of the scooter easily fit into the trunk of a car that is far from the most spacious and do not take up much space in passenger elevators, where space is usually sharply limited. All this makes the Ninebot KickScooter E22 a perfectly adapted solution for life in the big city.