It’s understandable that most drivers believe the ultimate source of the electricity provided in their cars comes from the battery, but what some may not understand is the part the alternator plays in keeping electricity stored in the battery. A car battery operates off the principle of chemical energy storage being converted to electrical energy. The lead plates sitting within a solution of sulfuric acid allows a chemical reaction to occur which releases electricity. As that reaction proceeds, the lead plates begin to shrink and the acid combines with the lead to create lead sulfate. Eventually, the reaction would stop and the production of electricity would end. That’s where the alternator becomes a simple, yet highly necessary, piece of equipment.
The alternator is simply an electrical motor in reverse; instead of being driven by electricity it turns with the drive belt of the automobile and uses a magnetic core and copper coils and brushes outside the core to create electricity. That electricity is then transferred to the battery where the reaction that had occurred to create electricity in the battery is reversed and in doing so the new energy is stored. This happens over and over again for car batteries, and although batteries have been used in automobiles for nearly one-hundred years they still have the same basic design.
Alternating-current (AC) is produced by modern automotive alternators and must be rectified to direct-current (DC) which is the current used by car batteries. The electronic control unit (ECU) which is also known as a car’s “computer,” is able to differentiate the amount of actual current being sent from the alternator to the battery. Since today’s automobiles need a great deal of electricity in order to operate, such as electric power steering and air conditioning, most modern car alternators are able to produce 50 to 70 amps of current.
Today’s alternators are more efficient than those of just a few decades ago and have a long lifespan. However, it may become necessary over time to either repair or replace the alternator if the battery begins to show signs of a lack of charge. The internal brushes and contacts found in most alternators can be easily replaced using kits found at any automotive parts retailer. Though repairing an alternator is not for the average car owner, it is also not out of the abilities of most people. Simple instructions are normally included with refurbish kits and online car forums can also be helpful in performing this task yourself.