A car battery is the base for electrical power that a car uses while in operation
and while the ignition key is in the "ON" position without the engine running. This
battery stores electric energy to start the engine and operate electrical accessories
in the electrical system throughout the car when the
is not running. Car batteries are equipped with a positive and negative terminals
from which the battery cables
are attached. Battery cables route power from the battery to the power distribution
center and engine block. Because most batteries are filled with acid, use caution
when working or testing a battery by wearing protective eyewear, gloves and clothing.
A battery work in two ways, first it supplies
the voltage the car needs to operate, next it produces enough amperage to turn the
starter motor. If the battery fails in either of these categories the engine will
not start, or the cars engine will stall. Most repair shops have a amperage tester
but you can perform your own amperage draw test using the vehicle as the tester.
A car battery is a rechargeable cell in the SLI (starting-lighting-ignition)
variety of batteries which are lead acid based. Lead acid batteries are the oldest
style of rechargeable batteries. The high power electrical output of a car battery
is necessary to supply a current needed for the engine starter. A normal car battery
provides about 12.6 volts and is divided into 6 separate cells, each cell produces
about 2.1 volts per cell. As the battery state of charge decreases the voltage produced
also decreases. Battery power is created through a chemical reaction where positive
and negative lead plates are immersed in an electrolyte solution (battery acid).
This solution is a combination of water and sulfuric acid. When the solution
interacts with the lead plates, the chemical interaction creates voltage. This voltage
is then released through the batteries positive terminal (red) and returned to the
negative terminal (black). Voltage from the alternator maintains the batteries state
of charge. This continuous cycle can produce electricity for years.
The most common way to recharge your battery is by a process called trickle charging.
This is performed using an inexpensive trickle charger. Most repair shops have a
more powerful and more expensive battery charger that is capable of charging at
a higher rate over a shorter time period. To jump start a car, a set of jumper cables
is needed. Visit -
Jump start battery
When replacing a battery its important to match the terminals (negative and positive)
to the new replacement battery. Visit -
Once the battery replacement is complete, start the engine and check the charging
system. Visit -
When the battery is overcharged or jump started, water in the electrolyte solution
is transformed into hydrogen and oxygen. This can cause an explosion from the battery
if a spark or another source of ignition is present. It also decreases the fluid
level inside the battery and can expose the lead plates. Exposure to oxygen can
damage these plates and reduces their ability to provide the chemical reaction needed.
Inspect your battery regularly, if acid is present replace the battery and check
the charging system. Be extremely careful when handling a car battery, gloves and
eye protection are recommended as battery acid is highly corrosive. When charging
a battery use caution, always connect the charge leads while the charger is OFF,
this will prevent a spark from being created. A battery is prone to an explosion
after a battery charge.
Clean Battery and Terminals
There are deposits that can form on the battery terminals. These deposits are
corrosive by-products of a normal battery charge and discharge function. While wearing
protective goggles and clothing, use a garden hose to rinse the battery completely
also rinse the surrounding area, this will dilute the acid to a non-corrosive state.
You can also apply baking soda to help neutralize the battery acid. Use a wire brush
on the battery terminals to clean thoroughly and reassemble, recheck charging system
Fully charge battery
Store in a cool place but not where it will be below 0 C or 32 degrees Fahrenheit
Check the battery every two months and recharge if needed
Remove all electrical connectors from the battery
Battery Cable Replacement
If excessive corrosion on battery cables are observed they should be replaced.
Corrosion can cause high resistance resulting in a starter operation failure. Avoid
using after market cables as they may not be manufactured to proper specifications
resulting in poor battery performance. Visit -
replacementRecycling Old Batteries
An old car battery is completely recyclable, contact your local recycling station,
auto part store or repair garage. Do not discard old batteries in land fills.
Written by Ken Lavacot Co-Founder and CEO of 2CarPros.com 35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.
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Article first published 2009-08-07 (Updated 2015-01-05)