2007 Grand Cherokee WK Factory Service Manual 8 - ELECTRICAL

BATTERY

DESCRIPTION



This vehicle is equipped with a single, 12-volt, maintenance-free battery located in the engine compartment. The battery is comprised of the following components:

  • Positive Post (1)
  • Vent (2)
  • Cell Cap (3)
  • Vent (4)
  • Cell Cap (5)
  • Vent (6)
  • Negative Post (7)
  • Indicator Eye (8) if equipped
  • Electrolyte Level (9)
  • Plate Groups (10)
  • Maintenance Free Battery assembly (11)

This battery is designed to provide a safe, efficient and reliable means of storing electrical energy in a chemical form. This means of energy storage allows the battery to produce the electrical energy 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 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 battery Group Size number, the Cold Cranking Amperage (CCA) rating, and the Reserve Capacity (RC) rating or Ampere-Hours (AH) rating can be found on the original equipment battery label. Be certain that a replacement battery has the correct Group Size number, as well as CCA, and RC or AH ratings that equal or exceed the original equipment specification for the vehicle being serviced. (Refer to 8 - ELECTRICAL/BATTERY SYSTEM - SPECIFICATIONS) for the proper factory-installed battery specifications.

OPERATION

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 cell caps cannot be removed, the battery must be replaced if the electrolyte level becomes low.

REMOVAL



NOTE: It may be necessary to use a battery terminal puller (2) if the battery cable terminal clamps are seized on to the battery posts.




1. Turn the ignition switch to the Off position. Be certain that all electrical accessories are turned off.
2. Loosen the battery negative cable terminal clamp pinch-bolt hex nut (4).
3. Disconnect the battery negative cable terminal clamp from the battery negative terminal post. If necessary, use a battery terminal puller to remove the terminal clamp from the battery post.
4. Loosen the battery positive cable terminal clamp pinch-bolt hex nut (8).
5. Disconnect the battery positive cable terminal clamp from the battery positive terminal post. If necessary, use a battery terminal puller to remove the terminal clamp from the battery post.


6. Remove the battery hold down bolt (2) and slide the hold down (4) up and forward in the battery tray slots (3).

WARNING: Wear a suitable pair of rubber gloves when removing a battery by hand. Safety glasses should also be worn. If the battery is cracked or leaking, the electrolyte can burn the skin and eyes.


7. Remove the battery (1) from the vehicle.

INSTALLATION




1. Clean and inspect the battery case, terminal posts and battery cable clamps, (Refer to 8 - ELECTRICAL/BATTERY SYSTEM - CLEANING).
2. Position the battery (1) into the vehicle. Ensure that the battery positive and negative terminal posts are correctly positioned. The battery cable terminal clamps must reach the correct battery terminal post without stretching the cables.
3. Install the battery hold down (4) by sliding it back and downward in the battery tray slots (3). Install the battery hold down bolt (2).

CAUTION: Be certain that the battery cable terminal clamps are connected to the correct battery terminal posts. Reverse battery polarity may damage electrical components of the vehicle.


4. Connect the battery positive cable terminal clamp (8) to the battery positive terminal post. Tighten the terminal clamp pinch-bolt hex nut to 5.5 N·m (50 in. lbs.).
5. Connect the battery negative cable terminal clamp (4) to the battery negative terminal post. Tighten the terminal clamp pinch-bolt hex nut to 5.5 N·m (50 in. lbs.).
6. Apply a thin coating of petroleum jelly or chassis grease to the exposed surfaces of the battery cable terminal clamps and the battery terminal posts.