Conventional Battery - Gasoline Engine

Fig 1: Battery Cell Cap Removal/Installation - Low-Maintanance

Courtesy of DAIMLERCHRYSLER CORP.

Low-maintenance batteries  are used on export vehicles equipped with a gasoline engine, these batteries have removable battery cell caps. See Fig 1. Water can  be added to this battery. Under normal service, the composition of this battery reduces gassing and water loss at normal charge rates. However these batteries may require additional distilled water after years of service.

Maintenance-free batteries  are standard factory-installed equipment on all domestic vehicles. Male post type terminals made of a soft lead material protrude from the top of the molded plastic battery case. See Fig 2 to provide the means for connecting the battery to the vehicle electrical system. The battery positive terminal post is visibly larger in diameter than the negative terminal post, for easy identification. 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 additional identification confirmation.

Fig 2: Maintenance-Free Battery - Domestic

Courtesy of DAIMLERCHRYSLER CORP.

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.

Some factory-installed batteries have a built-in test indicator (hydrometer). The color visible in the sight glass of the indicator will reveal the battery condition. For more information on the use of the built-in test indicator, refer to STANDARD PROCEDURE . The chemical composition of the metal coated plates within the low-maintenance battery used in export models reduces battery gassing and water loss at normal charge and discharge rates. Therefore, the battery should not require additional water in normal service. If the electrolyte level in this battery does become low, distilled water must be added. However, rapid loss of electrolyte can be caused by an overcharging condition. Be certain to diagnose the charging system after replenishing the water in the battery for a low electrolyte condition and before returning the vehicle to service. (Refer to ELECTRICAL/CHARGING - DIAGNOSIS AND TESTING) for additional information.

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 ELECTRICAL/BATTERY SYSTEM - SPECIFICATIONS)  for the proper factory-installed battery specifications.