Battery information center

Common battery related terminology


ACPI (Advanced Configuration and Power Interface) - A specification that allows the Operating System to control power management. Hardware information is made available to the operating system, and ACPI turns peripherals on and off for improved power management. ACPI also makes power management available for notebook PCs and allows the keyboard or mouse to bring the PC out of sleep mode.


Aging - the irreversible loss of capacity in rechargeable batteries.


Alternating Current (AC) - An electrical current which changes or reverses the direction of its flow. A notebook PC is running on AC power when its power cord is attached and plugged in.


Ampere, or Amp - The basic unit of measurement for electrical current. One volt flowing across one ohm resistance will create a current of one Amp.


Amp Hours - A unit of measure for a battery's storage capacity, this is calculated by multiplying the current in amperes by the time in hours of discharge. For example, a battery rated at 100 amp hours can dispense 20 amperes for 5 hours (10 amps X 5 hours = 100 amp hours).


Battery - A device that stores energy for later use. Most batteries consist of a group of two or cells connected together which transform chemical energy into electric energy.


Cycle - The process of one complete discharge and recharge for a rechargeable battery.


Cycle Life - The number of times a battery can be charged and discharged during its life.


Direct Current (DC) - An electrical current that flows in one direction only. A notebook PC is running on DC power when it is running on its battery.


Energy density - The amount of energy stored in a unit of weight or volume, expressed in watt hours per kilogram or watt hours per liter.


Energy storage - The amount of energy, expressed in watt hours, that is stored in a battery or battery pack.


Fast Charge Time - Typical fast charge time for a NiCd is 1 to 3 hours. The fast-charger detects the state-of-charge and switches to trickle charge when full-charge is reached.


Full Charge Capacity (FCC) - the actual capacity of a battery over time, expressed as a percentage of the initial rated capacity of the battery.


Lithium Ion, or Li-Ion - A rechargeable battery technology introduced in 1991 and currently used in notebook PCs. Li-Ion batteries are lighter, last longer, and discharge slower than previous battery technologies.


Memory effect - A phenomenon associated with some rechargeable batteries that sometimes occurs when the battery is recharged without first being fully discharged. Memory effect shortens battery life and reduces run-time between charges.


Ohm - A unit of electrical resistance. One volt flowing across one ohm resistance will create a current of one Amp.


Self discharge - The rate at which a battery loses energy when not in use. This can be expressed as a percentage loss per day or month.


Smart battery - Also known as an 'intelligent battery.' A battery pack containing internal circuitry that enables communication between the battery and the user.


Volt - The unit of measurement of electrical potential. One volt is the amount of electrical potential between two points on a conductor carrying a current of one ampere while one watt of power is dissipated between the two points. A single cell is two volts.


Watt - A unit used to measure total electrical power. It is calculated by multiplying amps by volts.