Putting it simply, the way
a battery works is that it converts chemical energy into
electrical energy. A battery is made up of one or more
voltaic cells. Each cell has a negative and positive
terminal which do not touch. Each - the negative and
positive - terminal is immersed in a solid or liquid
electrolyte.
Batteries made of of voltaic cells
are rated in volts. Alkaline and carbon-zinc cells are rated
at about 1.5 volts (each cell, not the entire battery).
However lithium cells can provide as much as 3 or more
volts. However, they are a more hazardous battery.
Manufacturers use a standard method
to determine how to rate their batteries.
The battery is discharged at a constant rate of current over
a fixed period of time, such as 10 hours or 20 hours, down
to a set terminal voltage per cell. So a 100 ampere-hour
battery is rated to provide 5 A for 20 hours at room
temperature.
