Battery: Description and Operation

BATTERY
The battery is an electrochemical device for converting chemical energy into electrical energy. The battery is also capable of storing energy and receiving a charge. The battery provides four basic functions.
1. Supplies electrical energy for accessories when the engine is not running.
2. Supplies energy to the cranking motor and ignition system as the engine is started.
3. Intermittently supplies energy to vehicle electrical devices when the electrical demands exceed the output of the generator.
4. The battery acts as a voltage stabilizer in the electrical system.

CHARGING SYSTEM
The battery and charging subsystem consist of a battery and a generator with a built in regulator. The system also includes the Powertrain Control Module (PCM) software required to provide idle boost. The battery supplies current to the starter to crank the engine during starting. After the engine starts, the charging system recharges the battery and supplies power to various electrical devices in the vehicle. The PCM monitors battery voltage and will increase idle speed if battery voltage drops below a calibrated amount.

FUSIBLE LINKS
In addition to circuit breakers and fuses, a fusible link is used between the starter and generator to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.

Not all fusible link open circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity.

Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. Each fusible link is four wire-gage sizes smaller than the cable it is designed to protect. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link.