In the LEV world, several variants such as lithium manganese
or lithium-iron phosphate are most common.
All of the lithium batteries currently used on LEVs are
potentially flammable and need a BMS, conscientious
manufacturer, conscientious safety testing, and appropriate
care and handling to reduce fire risk to users, dealers or
freight carriers. Lithium-battery fires get a lot of press but are
actually very rare.
Nominal cell voltage ranges in the area of 3. 5 volts, but
varies depending on metallurgy details. A chart of nominal
voltages can be found on Wikipedia.
MOSFET or FET: Is a metal-oxide semiconductor field-effect transistor. You can impress people by being able to
say that in one breath. The practical application for LEVs is
that a MOSFET is a switch that can be controlled by an IC
chip and, without physical movement, be turned on and off
under very high current loads. FETs are key components to
motor controllers, BMS and anything to do with high-power
electronics. They generate heat, and when overheated, they
Motor controller: An electronic circuit that controls the
speed of the electric motor, as well as various other functions
depending on the model and features of the vehicle.
Planetary gears: Are used inside gear-type hub motors to
reduce the high rpm of the electric motor to a usable speed
for the vehicle.
Neodymium: A rare earth metal that is used for the
production of high-energy permanent magnets. Such
magnets are commonly found in LEV motors and are a
source of considerable cost.
Ohm :The unit of resistance.
PAS bike: Pedal Assist System bike, usually designed
for the Japanese market and using a proportional power
paradigm. The motor delivers additional power in proportion
to the effort being exerted by the rider. “PAS” is a Yamaha
patent. This term is often misused to describe any bike where
the rider must pedal for the motor to run—such are better
Pedelec: An electric bicycle where the rider must pedal for
the motor to run. Variants of this are the PAS paradigm used
in Japan, and the EPAC paradigm used in Europe.
Regen or regeneration: Since a motor is mechanically
the same as a generator, it is possible in direct-drive motors
to electrically switch them to a generator and direct some
charge energy to the battery, thus recovering some of the
energy expended to reach speed or to climb a hill. The
amount of energy recovered in an electric bike is quite
modest, and this makes a good sales point, but is not a
major source of additional range.
Speed sensor (rotation sensor): Is a device that detects
rate of pedaling and is used to activate power in pedelecs.
Not as nice a “feel” as a torque sensor system. Can be
optical, hall effect or reed switch.
State of Charge (SOC): Is the gas gauge or how much
usable energy is in the battery. Seemingly a simple task, this
can be critical to user satisfaction and can be complex to
Throttle: A device operated by the user to control the
speed of the vehicle. Can be twist grip, thumb-operated, or
Torque: Twisting force.
Torque sensor: A device that detects and measures the
energy applied by pedaling. Torque sensors come in a variety
of types and configurations and are the preferred method of
determining if the rider is pedaling a pedelec (electric bike
where the rider must be pedaling for the motor to run) and a
required part of the Japanese proportional power paradigm
as required by Japanese law and patented by Yamaha.
Volts or voltage: Refers to the force that a given level of
electrical flow can exert.
Watts (unit of power): Refers to a unit of measurement
of how much work is done. This can be used for electrical,
muscle or ICE applications (and more). But for LEV use, watts
refers to how much work is being, or can be, accomplished
by the system or device. For example, a 500-watt motor is
capable of twice the work of a 250-watt motor, if all else is
equal. A human in really good condition will create about
75 watts of work over an extended period. Athletes can do
better, usually for short periods. One horsepower is about
Watt hour: A measurement of energy usually used to
describe battery capacity for LEVs. The formula that applies
is to multiply volts times Ah and this will give you watts. A
kilowatt (1000 watts) is a pretty big battery that might be
found on a motor scooter, while a pedelec may have about
360 watt hours in its 36-volt by 10Ah battery. ■