Amp: From “ampere,”
which is a measure of
the amount of electrical
current that passes a given
point in a given amount
of time. Used to describe
the demand or supply of
Amp hour or Ah: A
measure of energy that
is equal to the amount
of energy that passes a
given point in an hour. Ah
is usually used to describe
A feature of battery
management systems and
some chargers to cause all
the cells to be at the same
voltage. This increases
performance and battery life.
Battery or energy
storage device: Is a
combination of cells that
create a specific voltage
and current capability to
power an electric motor or
System (BMS): An
electronic circuit that
is found on advanced
batteries. The BMS prevents
damage to the battery and
prevents safety problems of
the battery overheating and
monitors the state of charge.
Brushless DC motor: Longer lasting and simpler than a
brush-type motor. There are no wear points other than the
bearings, but more costly in terms of control electronics, also
called a BLDC motor.
Brush-type DC motor: Uses brushes in the motor, which
creates a wear point: less expensive in terms of control
electronics and manufacture. Worn brushes create a black
dust that can build up in the motor and create a variety of
Cells: Individual electro chemical devices that create
electric current and are combined into packages to provide
appropriate voltage and current for a specific function called
Ceramic magnets: Used in electric motors. Lower in
performance and cost than neodymium magnets.
Cogging: The resistance that permanent magnets create
in a motor. This can be felt when a direct-drive motor is
not energized, and as it is rotated, there are moments of
resistance and release as it rotates.
DC: Direct current, or the form of electrical current used in
nearly all LEVs.
DC motor: A motor that uses direct current.
Direct-drive motor: Usually a hub motor that has no gear
reduction. Such motors are simpler and quieter, but often
larger and more expensive than gear-type motors.
Display: The dashboard or user interface that reports on
data such as speed, distance, time, and sometimes electrical
data of the battery or motor or both.
packaging: A foil/plastic
laminated pouch for the
cell. Soft to the touch, these
are not lithium polymer
batteries. They are lithium
batteries packaged in a
Usually refers to a hub
motor that uses a gear
reduction inside the hub
shell. Such motors are
usually less expensive than
direct-drive motors and get
good performance, but are
noisy and have more wear
Hall effect sensor: A
sensor that can detect a
magnetic field. Used in
motors, sensors, torque
sensors and throttles.
Horsepower: A unit
of work, about 750 watts.
From 550 pounds raised
one foot in one second—an
old mining measurement
that has transitioned
into the modern world to
describe power of motors.
Hub motor: An electric
motor located in the front or
These are old-technology
batteries of modest cost that
are used in most of the world’s light electric vehicles. While
heavy, they are reliable, have excellent discharge and charge
capabilities, and are nearly 100 percent recyclable. Also
called SVRLA and Pb A or Pb batteries.
Light electric vehicle: This refers to electric-powered
vehicles that usually, but not always, weigh less than 100
kilograms but can be as much as 500 kilograms, and have
two or three wheels. Electric bicycle, electric motor scooter,
light electric motorcycle, Segway, Trikke, YikeBike, are all
Light Electric Vehicle Association (LEVA): A trade group
that includes (at the time of this writing) 250 members from
29 countries. LEVA is focused on the promotion of electric
bikes, scooters and LEVs. www.levassociation.com
Lithium battery: Lithium batteries can store amazing
amounts of energy. They have excellent performance, weight,
life and temperature characteristics. And there are more than
100 types in development. Metallic lithium, when exposed
to water or moisture, will burn. But most batteries (and
elsewhere) use compounds of lithium that are more stable.
Some lithium batteries use electrolyte that is flammable as
There are also lithium battery metallurgies that will not
burn, but these are not in widespread use in the LEV world.
For the LEV technician, who may be working on a damaged
battery or a mislabeled battery, or a battery of unknown
origin and make, the practical mindset and stance is to
treat all lithium (and any unidentified) batteries as potentially