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Electric Bike Report
Watt’s what: A glossary of e-bike terms Charger. The electrical circuit that adjusts and controls current from the electrical mains to recharge the battery. It is very important to only use the correct charger for a given battery.
By Edward Benjamin
W
ant to know watt’s what? Have trouble telling your lithium ion from your lead acid? While electric bikes are very similar to regular bicycles, the electrical components require a very different vocabulary. Here’s a guide to the most common e-bike terms: Advanced battery. A battery using NiMH or lithium cells that usually requires a battery management system. It offers higher performance at a higher cost. Amp. Short for “ampere,” a measure of the amount of electrical current passing a given point in a given amount of time. If voltage is likened to the amount of water pressure in a garden hose, amps are like the volume of water that flows through the hose. Amp-hour (AH). A measure of the amount of energy passing a given point in an hour. Usually used to describe battery capacity. Battery. A combination of cells that creates a specific voltage and current capability to power an electric motor. Bottom bracket motor. A motor located in or adjacent to the bottom bracket or pedal axle. Sometimes called a central motor or mid-motor. Battery management system (BMS). An electronic circuit found on advanced batteries that prevents damage or overheating of the battery, and monitors the state of charge.
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Regulations The answer is no. If a regular bicycle is allowed, so is an e-bike. Except if, for example, you are in California. California law classifies e-bikes as mopeds. And many parks and pedestrian/bike paths also have signs that say “no motorized bicycles,” which because they are intended to ban mopeds also apply to e-bikes, said Rob Means. Means lobbies California legislators on behalf of the Light Electric Vehicle Association. “We’re trying to take the electric bikes out of that [moped] section so they cannot be denied access to these bike/
Cells. Individual electrochemical devices that create an electric current. A battery consists of a number of cells that are combined together to provide an appropriate voltage and current.
Edward Benjamin
Direct-drive motor. Typically, a hub motor that has no gear reduction. Such motors are simpler and quieter, but often larger and more expensive than gear-type motors. E-bike. A generic term for an electricpowered bike. Can refer to a pedelec as well as to a bike controlled by a throttle. Gear-type motor. Usually, a hub motor that uses a gear reduction inside the hub shell. Such motors are usually less expensive and perform well, but are noisy and have more wear points. Hub motor. An electric motor located in the front or rear hub. Lead acid battery. An old-technology battery of modest cost, used in most of the world’s light electric vehicles. They are heavy but reliable, have excellent discharge and charge capabilities, and are nearly 100 percent recyclable.
ped paths,” Means said. Means said LEVA is seeking a legislative sponsor for a proposed measure in the California Assembly that would clarify that an electric bicycle should be treated the same as regular bicycles. It would allow motors of up to 1,000 watts but would limit speeds to 20 mph. “If we can get California to move, then it should be easier to move everybody else,” Means said. Perhaps the biggest discrepancy between legality and reality is New York, where e-bikes are officially illegal. New York City police typically haven’t enforced the ban. In fact, one of the country’s oldest and most successful e-bike retailers, NYCeWheels, operates in Manhattan.
Lithium battery. An advanced battery with excellent performance, light weight and longer life. Comes in several variants including lithium manganese and lithium iron phosphate. All lithium batteries are flammable and require a battery management system. Motor controller. An electronic circuit that controls the speed of the electric motor and other functions, depending on the model and features of the e-bike. Pb or Pb A battery. See lead acid battery. NiCad. Short for “nickel cadmium,” a type of battery found on some older e-bike models. Toxic, with lower performance than NiMH and lithium batteries. NiMH. Short for “nickel metal hydride,” a nontoxic type of battery with performance between lead acid and lithium batteries. Occasionally found on e-bikes. Pedelec. An e-bike in which the motor operates only while the rider is pedaling. Common in Europe and Japan. Speed sensor. A device that detects rate of pedaling and is used to activate power in a pedelec. Not as nice a “feel” as a torque sensor system. Thermal runaway. What happens when a battery overheats and, in some cases, catches fire. Caused by poorly made or abused advanced batteries. Can be prevented in most cases with well-designed cells and a battery management system. Throttle. A user-operated device that controls the speed of the e-bike independent of pedaling. Often a twist grip or thumb-operated.
But e-bikes have recently been caught up in what Moore calls the “Chinese takeout food controversy.” Following a spate of accidents caused by restaurant delivery cyclists—including a 2009 incident when a cyclist hit a pedestrian, who died of his injuries—the New York City Council last fall voted to require commercial delivery cyclists to take a safety course. Their employers can be fined up to $300 if they don’t provide helmets, bells and headlights to their riders. “Unfortunately, those guys are really a menace. They do the same things [on e-bikes] that they did before on regular bikes,” said Bert Cebular, founder of NYCeWheels. “They ride on sidewalks, they run through red lights. They just
Torque sensor. A device that measures the energy applied by pedaling. This is preferred for pedelecs. Vehicle controller. An electronic circuit that monitors and regulates the motor controller, user interface, battery management system and other features. Volt. The unit of electric potential difference, or the size of the force behind a given level of electrical flow. Voltage is often likened to the amount of pressure in a water hose; use a larger hose, and the pressure remains the same but the flow, or amps, increases. Watt. A unit of measurement of the amount of work being done. For e-bikes, watts refer to the amount of work that can be accomplished by a system. For example, a 500-watt motor is capable of twice the work of a 250watt motor, all else being equal. One horsepower equals about 750 watts. A person in very good physical condition can create about 75 watts of work over an extended period. Watt-hour. A measurement of energy usually used to describe battery capacity for e-bikes. Volts multiplied by amphours equals watt-hours. A typical pedelec offers 360 watt-hours if it has a 36-volt, 10 amp-hour battery. Wiring harness. The wires, connectors and switches that carry electrical current and signals about the vehicle. Edward Benjamin is managing director of eCycleElectric Consultants and founder and chairman of the Light Electric Vehicle Association. A fuller version of this glossary is available at eCycleElectric.com.
don’t care that they run people over. Now they’re doing it on electric bikes, which gives electric bikes a bad name.” Cebular said attempts to legalize ebikes in New York state have come close to succeeding in the past, but he isn’t aware of current efforts in the state legislature. Cebular said his e-bike customers typically don’t run into problems because they don’t stand out, and ride with common sense. “The typical electric bike blends in nicely. Most won’t even know it’s electric,” he said. “The bottom line is, even with the crackdown, they’re not going to be hassled because cops are looking for delivery guys doing the wrong thing.”