Battery: Description and Operation
BATTERY SYSTEMA single 12-volt battery system is standard factory installed equipment on this model. All of the components of the battery system are located within the engine compartment of the vehicle. The service information for the battery system in this vehicle covers the following related components, which are covered in further detail later:
- Battery - The storage battery provides a reliable means of storing a renewable source of electrical energy within the vehicle.
- Battery Cables - The battery cables connect the battery terminal posts to the vehicle electrical system.
- Battery Holddown - The battery holddown hardware secures the battery in the battery tray in the engine compartment.
- Battery Tray - The battery tray provides a secure mounting location in the vehicle for the battery and an anchor point for the battery holddown hardware.
For battery system maintenance schedules and jump starting procedures, see the owner's manual in the vehicle glove box. Optionally refer to Lubrication and Maintenance for the proper battery jump starting procedures. While battery charging can be considered a maintenance procedure, the battery charging procedures and related information are located in the service procedures section. This was done because the battery must be fully charged before any battery system diagnosis or testing procedures can be performed. Refer to Standard Procedures for the proper battery charging procedures.
The battery system is designed to provide a safe, efficient, reliable and mobile means of delivering and storing electrical energy. This electrical energy is required to operate the engine starting system, as well as to operate many of the other vehicle accessory systems for limited durations while the engine and/or the charging system are not operating. The battery system is also designed to provide a reserve of electrical energy to supplement the charging system for short durations while the engine is running and the electrical current demands of the vehicle exceed the output of the charging system. In addition to delivering, and storing electrical energy for the vehicle, the battery system serves as a capacitor and voltage stabilizer for the vehicle electrical system. It absorbs most abnormal or transient voltages caused by the switching of any of the electrical components or circuits in the vehicle.
Fig. 4 Low-Maintenance Battery - Typical:
BATTERY
A large capacity low-maintenance storage battery (Fig. 4) is standard factory-installed equipment on this model. Refer to Battery System Specifications for the proper specifications of the factory-installed batteries available on this model. Male post type terminals made of a soft lead material protrude from the top of the molded plastic battery case to provide the means for connecting the battery to the vehicle electrical system. The battery positive terminal post is physically larger in diameter than the negative terminal post to ensure proper battery connection. The letters POS and NEG are also molded into the top of the battery case adjacent to their respective positive and negative terminal posts for identification confirmation. Refer to Battery Cables for more information on the battery cables that connect the battery to the vehicle electrical system.
The battery is made up of six individual cells that are connected in series. Each cell contains positively charged plate groups that are connected with lead straps to the positive terminal post, and negatively charged plate groups that are connected with lead straps to the negative terminal post. Each plate consists of a stiff mesh framework or grid coated with lead dioxide (positive plate) or sponge lead (negative plate). Insulators or plate separators made of a non-conductive material are inserted between the positive and negative plates to prevent them from contacting or shorting against one another. These dissimilar metal plates are submerged in a sulfuric acid and water solution called an electrolyte.
The factory-installed battery has a built-in test indicator (hydrometer). The color visible in the sight glass of the indicator will reveal the battery condition. Refer to Standard Procedures for the proper built-in indicator test procedures. The factory-installed low-maintenance battery has non-removable battery cell caps. Water cannot be added to this battery The battery is not sealed and has vent holes in the cell caps. The chemical composition of the metal coated plates within the low-maintenance battery reduces battery gassing and water loss, at normal charge and discharge rates. Therefore, the battery should not require additional water in normal service. Rapid loss of electrolyte can be caused by an overcharging condition. Be certain to diagnose the charging system before returning the vehicle to service. (Refer to CHARGING - DIAGNOSIS AND TESTING).
The battery is designed to store electrical energy in a chemical form. When an electrical load is applied to the terminals of the battery an electrochemical reaction occurs. This reaction causes the battery to discharge electrical current from its terminals. As the battery discharges, a gradual chemical change takes place within each cell. The sulfuric acid in the electrolyte combines with the plate materials, causing both plates to slowly change to lead sulfate. At the same time, oxygen from the positive plate material combines with hydrogen from the sulfuric acid, causing the electrolyte to become mainly water. The chemical changes within the battery are caused by the movement of excess or free electrons between the positive and negative plate groups. This movement of electrons produces a flow of electrical current through the load device attached to the battery terminals.
As the plate materials become more similar chemically, and the electrolyte becomes less acid, the voltage potential of each cell is reduced. However, by charging the battery with a voltage higher than that of the battery itself, the battery discharging process is reversed. Charging the battery gradually changes the sulfated lead plates back into sponge lead and lead dioxide, and the water back into sulfuric acid. This action restores the difference in the electron charges deposited on the plates, and the voltage potential of the battery cells. For a battery to remain useful, it must be able to produce high-amperage current over an extended period. A battery must also be able to accept a charge, so that its voltage potential may be restored.
The battery is vented to release excess hydrogen gas that is created when the battery is being charged or discharged. However, even with these vents, hydrogen gas can collect in or around the battery. If hydrogen gas is exposed to flame or sparks, it may ignite. If the electrolyte level is low, the battery may arc internally and explode. If the battery is equipped with removable cell caps, add distilled water whenever the electrolyte level is below the top of the plates. If the battery cell caps cannot be removed, the battery must be replaced if the electrolyte level becomes low.
Fig. 12 Battery Hold-downs:
BATTERY HOLDDOWN
The battery hold down hardware (Fig. 12) includes a J-bolt, a long stud, two hex nuts with washers and a hold down strap. The battery hold down strap consists of a formed steel rod with a stamped steel angle bracket welded to each end. The hold down strap assembly is then plastic-coated for corrosion protection.
When installing a battery into the battery tray, be certain that the hold down hardware is properly installed and that the fasteners are tightened to the proper specifications. Improper hold down fastener tightness, whether too loose or too tight, can result in damage to the battery, the vehicle or both. (Refer to BATTERY SYSTEM/BATTERY HOLDDOWN - INSTALLATION) for the location of the proper battery hold down installation procedures, including the proper hold down fastener tightness specifications.
The battery hold down hardware secures the battery in the battery tray in the engine compartment. This hardware is designed to prevent battery movement during vehicle operation. Unrestrained battery movement during vehicle operation can result in damage to the vehicle, the battery or both.
The hooked end of the battery hold down J-bolt is installed through holes located in the battery support on the inboard side of the battery tray. One end of the battery hold down stud is threaded into a weld nut on a tab located on the cowl side inner panel on the outboard side of the battery tray. After the battery is properly positioned in the battery tray the battery hold down strap is installed across the top of the battery case and over the ends of the J-bolt and the long stud. A hex nut with washer is then installed over the threaded ends of the J-bolt and the long stud and tightened to securely hold down the battery in the battery tray.
Fig. 13 Battery Cables:
BATTERY CABLES
The battery cables (Fig. 13) are large gauge, stranded copper wires sheathed within a heavy plastic or synthetic rubber insulating jacket. The wire used in the battery cables combines excellent flexibility and reliability with high electrical current carrying capacity.
The battery cables cannot be repaired and, if damaged or faulty they must be replaced. Both the battery positive and negative cables are available for service replacement only as a unit with the battery positive cable wire harness or the battery negative cable wire harness, which may include portions of the wiring circuits for the generator and other components on some models. Refer to Wiring Diagrams for the location of more information on the various wiring circuits included in the battery cable wire harnesses for the vehicle being serviced.
The battery cables feature a stamped brass clamping type female battery terminal crimped onto one end of the battery cable wire and then solder-dipped. A square headed pinch-bolt and hex nut are installed at the open end of the female battery terminal clamp. The battery positive cable also includes a red molded rubber protective cover for the female battery terminal clamp. Large eyelet type terminals are crimped onto the opposite end of the battery cable wire and then solder-dipped. The battery positive cable wires have a red insulating jacket to provide visual identification and feature a larger female battery terminal clamp to allow connection to the larger battery positive terminal post. The battery negative cable wires have a black insulating jacket and a smaller female battery terminal clamp.
The battery cables connect the battery terminal posts to the vehicle electrical system. These cables also provide a return path for electrical current generated by the charging system for restoring the voltage potential of the battery The female battery terminal clamps on the ends of the battery cable wires provide a strong and reliable connection of the battery cable to the battery terminal posts. The terminal pinch bolts allow the female terminal clamps to be tightened around the male terminal posts on the top of the battery The eyelet terminals secured to the ends of the battery cable wires opposite the female battery terminal clamps provide secure and reliable connection of the battery to the vehicle electrical system.
The battery positive cable terminal clamp is crimped onto the ends of two wires. One wire has an eyelet terminal that connects the battery positive cable to the B(+) terminal stud of the Power Distribution Center (PDC), and the other wire has an eyelet terminal that connects the battery positive cable to the B(+) terminal stud of the engine starter motor solenoid. The battery negative cable terminal clamp is also crimped onto the ends of two wires. One wire has an eyelet terminal that connects the battery negative cable to the vehicle powertrain through a ground screw on the front of the left engine cylinder head. The other wire has an eyelet terminal that connects the battery negative cable to the vehicle body through a ground screw on the left side of the dash panel, just behind the battery.
Fig. 16 Battery Tray Orientation:
BATTERY TRAY
The battery is mounted in a molded plastic tray (Fig. 18) located in the left front corner of the engine compartment. The battery tray is secured with screws to a stamped steel battery tray support on the left front wheelhouse inner panel, to a stamped steel bracket on the left side of the dash panel and to the left cowl side panel. The battery tray support is secured with nuts to two weld studs on the front upper surface of the left front wheelhouse inner panel. The battery tray bracket is spot welded to the left side of the dash panel in the engine compartment.
A hole in the bottom of the battery tray is fitted with a formed drain tube. A second hole in the bottom of the tray is fitted with a battery temperature sensor. (Refer to CHARGING/BATTERY TEMPERATURE SENSOR - DESCRIPTION).
The battery tray provides a mounting location and support for the vehicle battery. The battery tray support supports the battery tray and provides an anchor point for the inboard battery hold down hardware. A tab with a weld nut on the cowl side inner panel provides the anchor point for the outboard battery hold down hardware. The battery tray and the battery hold down hardware combine to secure and stabilize the battery in the engine compartment, which prevents battery movement during vehicle operation. Unrestrained battery movement during vehicle operation could result in damage to the vehicle, the battery or both. The battery tray drain tube directs spilled water or electrolyte from a leaking battery to the ground through another hole in the front extension of the left front wheelhouse inner panel.