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What is a Battery?
A battery stores chemical energy, which can be converted into electrical energy.
The physical part and electrical symbol for a battery are shown below:
Primary batteries are ready to produce current as soon as they are manufactured. Primary
batteries are generally used in flashlights and must be replaced when they go "dead".
Secondary batteries can be recharged by applying an electrical current, which reverses the
chemical reactions that occur during its use. All car batteries are secondary batteries that need
constant recharging by the car's alternator.
The capacity of a battery depends on the discharge conditions, such as the magnitude of the
current and the duration of the current. The Battery Capacity (AH, Ampere Hour) is defined as
the maximum constant current that a fully charged battery can supply for 20 hours at 68°F (20°C)
down to a predetermined terminal voltage. Thus a 1000mAH (milliamp hour) battery will deliver
50mA over a period of 20 hours at room temperature. However, if it is discharged at 100mA, it will
run out of charge within 10 hours.
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