ELECTRIC
VEHICLE BATTERY GLOSSARY
AEC-Q100 STANDARD
The
AEC-Q100 standard includes customer specific requirements
(CSR). ISO/TS-16949. It is an international standards Automotive
Quality Systems technical specification. It defines the purpose
of establishing common part-qualification and quality-system
standards for automotive components. It contains detailed
qualification and re-qualification requirements, and includes
unique test methods and guidelines for the use of generic
data. Components meeting these specifications are suitable
for use in the harsh automotive environment without additional
component level qualification testing.
BATTERY
PROTECTION
Battery
protection and monitoring are a necessity with Li-ion battery
packs. At the higher operating voltages experienced in electric
vehicles, an overvoltage can be catastrophic. Although the
quality of battery fabrication has improved, guarding against
higher temperature and fault conditions in any automotive
application remains crucial for reliable operation.
BATTERY
STACKS
For
electric vehicle transportation applications they can typically
involve hundreds of cells, providing several hundred volts.
Although these stacks are inherently dangerous, they must
still communicate with the cell monitoring electronics, which
are usually located within the battery enclosure. Thus, the
communications method must be safe and reliable.
C20,
C6, C1, ETC
An
expression describing rate of discharge. The number indicates
the number of hours to completely discharge the battery at
a constant current. So C/20 is the current draw at which the
battery will last for 20 hours, C/1 is the current at which
the battery will last 1 hour. The useful capacity of a battery
changes depending on the discharge rate, so battery capacities
are stated with respect to a particular rate. For instance,
a battery is rated at 42 Ah (ampere-hours) at the C/10 rate
of 4.2A, but only 30 Ah at the C/1 rate of 30A.
COLD
CRANKING AMPS
A
performance rating for automobile starting batteries. It is
defined as the current that the battery can deliver for 30
seconds and maintain a terminal voltage greater than or equal
to 1.20 V per cell, at 0°F (-18°C), when the battery
is new and fully charged. Starting batteries may also be rated
for Cranking Amps, which is the same thing but at a temperature
of 32°F (0°C).
CYCLE
LIFE
How
many charge/discharge cycles the battery can endure before
it loses its ability to hold a useful charge. Cycle life typically
depends on the depth of discharge (DOD). For example, if a
hypothetical battery pack will propel your car for a maximum
range of 100 miles, and you drive 50 miles between charges,
(50% DOD) then you may get 600 trips before replacing the
pack; but if you drove 80 miles between charges, you might
only get 400 trips before the pack wears out.
DEPTH
OF DISCHARGE
The
amount of energy that has been removed from a battery (or
battery pack). Usually expressed as a percentage of the total
capacity of the battery. For example, 50% depth of discharge
means that half of the energy in the battery has been used.
80% DOD means that 80% of the energy has been discharged,
so the battery now holds only 20% of its full charge.
DIGITAL
ISOLATOR
Digital
isolators provide isolation so that the high voltage output
from an EV battery can be monitored at a lower voltage.
ELECTRIC
VEHICLES
This
can refer to a vehicle that employs only batteries (EV) that
are rechargeable, or a hybrid electric vehicle (HEV) that
uses a car's internal small gasoline engine to recharge the
battery, or a plug-in hybrid vehicle (PHEV) that can be recharged
form a power line or from a car's internal gasoline engine.
ENERGY
DENSITY
The
amount of energy that can be contained in a specific quantity
of the fuel source. Typically quoted in watt-hours per pound,
wh/lb, or watt-hours per kilogram, wh/kg. Battery technologies
such as NiMH and li-ion are in the 80-135 wh/kg range.

LITHIUM-ION
(LI-ION)
A
type of rechargeable battery in which lithium ions move from
the negative electrode to the positive electrode during discharge,
and reversely when charged. Different types of lithium-ion
batteries use different chemistries and have different characteristics.
The typical output voltage of a Li-ion battery is 4.0V.
LITHIUM-ION
POLYMER (LI-POL)
Rechargeable
batteries (secondary cell batteries). Normally these batteries
consist of several identical secondary cells in parallel to
increase the discharge current capability.
NICKEL
CADMIUM
Newer
rechargeable technologies, such as nickel-metal hydride (NiMH)
have mostly replaced NiCad, because they have better energy
characteristics and don't contain toxic cadmium, a carcinogen.
The battery has a nickel-hydroxide cathode, a cadmium anode,
and aqueous potassium hydroxide electrolyte. Average battery
output is about 1.3 V.
NICKEL
METAL HYDRIDE
NiMH
batteries are common in laptop computers and cellular phones.
NiMH is similar to nickel-cadmium but uses a metal hydride
anode; a variety of metal alloys are used. Average battery
output is about 1.3 V. These batteries are also used in electric
cars, like the Toyota Prius.
RESERVE
CAPACITY
A
performance rating for automobile starting batteries, it is
the number of minutes at which the battery can be discharged
at 25 A and maintain a terminal voltage higher than 1.75 V/cell,
on a new, fully charged battery at 80° F (27°C).
SLI
BATTERY (Lead/Acid type)
Starting,
Lighting, and Ignition battery, a battery designed for use
in a conventional gasoline automobile. An SLI battery is designed
to give a lot of current during starting, but then to be recharged
immediately by the car's alternator. Electric cars usually
have a portion of the total battery capacity set aside for
SLI use.
STATE
OF CHARGE
The
amount of electrical charge in the battery, expressed as a
percentage of the difference between the fully-charged and
fully-discharged states.
TRACTION
BATTERY
A
battery designed to be used to provide the power to move a
vehicle, e.g. to be used in an electric car. An electric car
can have a battery pack consisting of 100 Li-ion cells.
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