The automobile charging system provides electrical power for operation of the vehicle's ignition and starting systems as well as all electrical accessories. The battery serves as an electrical surge, or storage tank, storing (in chemical form) the energy originally produced by the engine driven alternator. The system also provides a means of regulating alternator output to protect the battery from being overcharged, and to avoid excessive voltage to the accessories.
The storage battery is a chemical device incorporating parallel lead plates in a tank containing a sulfuric acid/water solution. Adjacent plates are slightly dissimilar, and the chemical reaction of the two dissimilar plates produces electrical energy when the battery is connected to a load such as the starter motor. The chemical reaction is reversible, so that when the alternator is producing a voltage (electrical pressure) greater than that produced by the battery, electricity is forced into the battery, and the battery is returned to full charge.
The vehicle's alternator is driven by a belt, or belts from the engine’s crankshaft. In an alternator, the field rotates while all the current produced passes only through the stator winding. The brushes bear against continuous slip rings rather than a commutator. This causes the current produced to periodically reverse the direction of its flow creating alternating current (AC). Diodes (electrical one-way switches) block the flow of current from traveling in the wrong direction. A series of diodes is wired together to permit the alternating flow of the stator to be converted to a pulsating, but unidirectional flow at the alternator output. The alternator's field is wired in series with the voltage regulator.
The voltage regulator consists of several circuits. Each circuit has a core, or magnetic coil of wire, which operates a switch. Each switch is connected to ground through one or more resistors. The coil of wire responds directly to system voltage. When the voltage reaches the required level, the magnetic field created by the winding of wire closes the switch and inserts a resistance into the alternator field circuit, thus reducing the output. The contacts of the switch cycle open and closed many times each second to precisely control voltage.
WARNING
Batteries produce explosive gases. Batteries contain corrosive acid. Batteries supply levels of electrical current high enough to cause burns. Therefore, in order to reduce the risk of personal injury while working near a battery, observe the following guidelines:
CAUTION
Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF unless instructed otherwise in these procedures.
WARNING
Ensure that the vehicle is properly supported and squarely positioned prior to lifting.
WARNING
Ensure that the hoist does not contact fuel or brake lines.
WARNING
To help avoid personal injury when a vehicle is on a hoist, provide additional support for the vehicle at the opposite end from which components are being removed. This will reduce the possibility of the vehicle falling off of the hoist.
WARNING
The centerline of gravity on front-wheel drive vehicles is further forward than on rear-wheel drive vehicles. Therefore, whenever removing major components from the rear of a front-wheel drive vehicle, while supported on a hoist, it is mandatory to support the vehicle in a manner to prevent the possibility of a vehicle tipping forward.
WARNING
To help avoid personal injury, always use jack stands when working on or under any vehicle that is supported only by a jack.
CAUTION
When jacking or lifting a vehicle at the frame side rails or other prescribed lift points, be certain that lift pads do not contact the catalytic converter, brake pipes or cables, or fuel lines. Such contact may result in damage or unsatisfactory vehicle performance.