Proper maintenance will prolong the life of a battery and will aid in assuring that it is capable of satisfying its design requirements. A good battery maintenance program will serve as a valuable aid in determining the need for battery replacement. Battery maintenance should always be performed by trained personnel knowledgeable of batteries and the safety precautions involved.

Most of the following material concerns flooded, non-maintenance-free batteries. However, so called "maintenance-free" and valve-regulated batteries also require some maintenance. They do not require water addition or checking of specific gravity, but they may require periodic cleaning, monitoring of cell and battery total float voltage, load (capacity) testing, terminal resistance measurement, or cleaning and torquing of terminal bolts depending on the importance of the application.

General

In general, a good maintenance and inspection program should be based on the recommendations in ANSI/IEEE Std 450, IEEE Recommended Practice for Maintenance, Testing, and Replacement of Large Lead Storage Batteries for Generating Stations and Substations; and in DOE-STD-3003-94, Backup Power Sources for DOE Facilities. Some of the recommended practices from these and other references are presented in the following paragraphs.

Flooded lead-acid batteries can function for 10 years or longer if properly maintained. The six general rules of proper maintenance are

1. Match the charger to the battery requirements.

2. Avoid overdischarging the battery.

3. Maintain the electrolyte at the appropriate level (add water as required).

4. Keep the battery clean.

5. Avoid overheating the battery.

6. Provide an equalizing charge periodically to weak batteries/cells.

Matching the Charger to Battery Requirements

Poor charging practice is responsible for shortening the life of a battery more than any other cause. Charging may be accomplished by various methods, but the objective of driving current through the battery in the opposite direction of discharge remains the same. The most important aspect of charging is matching the charger to the battery application. When choosing a charger, it is necessary to consider the type of battery, the way in which the battery will be discharged, the time available for charge, the temperature extremes the battery will experience, and the number of cells in the battery (output voltage). It is important to consult the battery manufacturer at the time of purchase to determine the appropriate charging method.

In general, lead-acid batteries may be recharged at any rate that does not produce excessive gassing, overcharge, or high temperatures. Discharged batteries may be recharged at a high current initially. However, once the battery approaches its full charge the current must be decreased to reduce gassing and excessive overcharging.

A wide variety of schemes exist for charging lead-acid batteries. Although a complete discussion of various charging techniques is beyond the scope of this Primer, a general description of the more common methods follows.