A battery stores electricity for future use. It develops voltage from the chemical
reaction produced when two unlike materials, such as the positive and negative plates,
are immersed in the electrolyte, a solution of sulfuric acid and water. In a typical
lead-acid battery, the voltage is approximately 2 volts per cell, for a total of 12
volts. Electricity flows from the battery as soon as there is a circuit between the
positive and negative terminals. This happens when any load that needs electricity,
such as the radio, is connected to the battery.
Most people don't realize that a lead-acid battery operates in a constant process of
charge and discharge. When a battery is connected to a load that needs electricity,
such as the starter in your car, current flows from the battery. The battery begins
to be discharged.
In the reverse process, a battery becomes charged when current flows back into it,
restoring the chemical difference between the plates. This happens when you're driving
without any ccessories and the alternator puts current back into the battery.
As a battery discharges, the lead plates become more chemically alike, the acid becomes
weaker, and the voltage drops. Eventually the battery is so discharged that it can no
longer deliver electricity at a useful voltage
You can recharge a discharged battery by feeding electrical current back into the
battery. A full charge restores the chemical difference between the plates and leaves
the battery ready to deliver its full power.
This unique process of discharge and charge in the lead-acid battery means that energy
can be discharged and restored over and over again. This is what's known as the cycling
ability in a battery.
If the battery won't start your car, you usually refer to it as "dead," even though
that's not technically correct. A battery that's merely discharged - from leaving your
headlights on or from a damaged alternator -- can be recharged to its full capacity.
But a battery that's at the end of its service life can't be recharged enough to
restore it to a useful power level. Then it truly is dead, and must be replaced.
If the battery is discharged, not dead, you can jump-start it from another fully
charged battery. About 30 minutes of driving should allow the alternator to fully
charge the battery. But if the alternator or another part of the electrical system in
your car is damaged, they won't be able to recharge your battery. So if your battery
keeps discharging, before you replace it, have your electrical system checked. What
looks like a bad battery could be an electrical system problem. If you have a bad
component in the electrical system, it will keep draining a new battery, and you'll be
stranded again and again.
|
HOME
