There are many possible types of electric bikes with several technologies available for electric motors, varying in cost and design.The geared motor units and direct-drive are both used. An electric power-assist system may be added to almost any pedal cycle. Chain drive and hub motors are both common, abrasion drive beneath so. There are some available with up to 2000 watts such as Crystalyte Phoenix although most hub motors are in the 250w to 450w category.
Electric bicycles are generally powered by rechargeable batteries. These are normally charged from the utility supply (mains), with perhaps the option of using the motor to effect regenerative braking or charging while being pedalled or rolling downhill. With recharging via solar panels and, to a lesser extent, other alternative energy sources such as fuel cells,there are also experiments. Most modern electric bikes use technologies such as rare earth magnets, pulse width modulated power electronic control and regenerative braking to improve efficiency. Batteries are usually either Li-ion or lead-acid, NiCd, NiMH. Offering the advantage of lighter weight for the same energy storage capability but at a higher cost,lithium ion polymer batteries are now beginning to be used as well.
An electric automatic bike can be power-on-demand, area the motor is activated by a handlebar army throttle, and/or a pedelec (from pedal electric), area the electric motor is adapted by pedaling. These may accept a apparatus such as a crank sensor to ascertain back the user is pedaling, or a added adult torque sensor. The amount of abetment can usually be controlled to optimize array life.
Range is a key application with electric bikes, and is afflicted by factors such as motor efficiency, array capacity, ability of the active electronics, aerodynamics, hills and weight of the bike and addition combined. The range of an electric bike is usually stated as somewhere between 7km (uphill on electric power only) to 70km (minimum assistance).
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