2240 SRM 1
Electrical Terms
Figure 5. Discharged Cell
Figure 6. Charging Cell
Electrical Terms
Voltage: Is an electromotive force (EMF) (also called
"potential difference") caused by the difference in
electric charge between two points. See Figure 7.
Ampere: Is a measurement of electric current.
Watt: Is a measure of electric power. The number
of watts is equal to the number of volts multiplied
by the number of amperes. A kilowatt-hour is 1000
watts of electric power used in 1 hour.
Ohms: Is the measurement of electrical resistance.
Polarity: In a battery, the electric current is shown
to flow from the positive terminal to the negative ter-
minal.
Maintenance-Free Battery: The electrolyte level
in the battery does not need to be checked during
the life of the battery. Maintenance-free batteries
use a calcium alloy of lead instead of an antimony
alloy, which reduces the amount of electrolysis. In a
maintenance-free battery, the amount of free-stand-
ing electrolyte above the plates is much higher, en-
suring enough electrolytes to keep the plates covered
during extended periods of use. Therefore, there is
no need to add water to a maintenance-free battery
during the course of its life.
Flooded Cell: This is a lead acid battery that has
free flowing electrolyte fluid in each cell of the bat-
tery. The electrolyte is a mixture of sulfuric acid and
water.
Direct Current (DC): When the voltage between
the two terminals is always the same polarity, the
current flow and voltage are called Direct Current.
Alternating Current (AC): When the polarity of
voltage between two terminals is changing between
positive and negative at a quick and constant rate,
the voltage is called Alternating Current.
3