Common Causes Of Battery Failures

All batteries have a limited life span. However the life span can be considerably shortened by certain factors which tend to cause premature battery failure. The factors discussed below are some of the most common causes of battery failure. Given the roles batteries play and will continue to play in our everyday life, a thorough understanding of these factors will enable engineers and technicians involved in the maintenance of batteries prevent the occurrence of some of these factors in order to prolong battery life.

The factors discussed below are mostly applicable to VRLA (Valve Regulated Lead Acid) batteries which have almost completely replaced conventional lead acid batteries with refillable liquid sulphuric acid electrolyte. VRLA batteries are designed to be maintenance free and the hydrogen that is emitted is recombined internally so that the electrolyte (essentially a paste) does not need replacing over the life of the battery, a valve is installed to release any excess pressure that may build up if the battery were failing. A key drawback of VRLA batteries is the short service life which was procured at the expense of low maintenance.

Elevated Temperatures

Anticipated battery life is specified by the manufacturer for batteries installed in an environment at or near the reference temperature of 25°C (77°F). Above this temperature, battery life is reduced. The chief aging mechanism is accelerated corrosion of the positive plates, grid structure, and strap, which increases exponentially as a function of temperature. Elevated temperatures reduce battery life. An increase of 8.3°C (15°F) can reduce lead-acid battery life by 50% or more. 

Repeated Cycling

Repeated cycling from fully charge to fully discharge and back may cause loss of active materials from the positive plates. This reduces battery capacity and its useful life.

Overcharging

Overcharging by the battery charging system causes excessive gassing and high internal heat. Too much gassing can lead to the removal of active material from the plates. Too much heat can also oxidize the positive plate material and warp the plates.

Undercharging

A faulty charging system will not maintain the battery at full charge. Severe undercharging allows sulfate on the plates to become hard and impossible to remove by normal charging. The undercharged battery may fail to deliver the required power needed for its application.

Over discharge

Over discharge leads to hydration. Hydration occurs in a lead-acid battery that is over discharged and not promptly recharged. Hydration results when the lead and lead compounds of the plates dissolve in the water of a discharged cell and form lead hydrate, which is deposited on the separators. When the cell is recharged, multiple internal short circuits occur between the positive and negative plates. Once hydration is evident, the cell is permanently damaged. Hydration is not visible in VRLA cells because the containers are opaque

Vibration

A battery must be mounted securely. Vibrations can loosen connection, crack the case and damage internal components.

DC Ripple Current

Excessive DC ripple current might contribute to battery aging. VRLA batteries are extremely susceptible to ripple current since it can lead to cell heating and will accelerate the degradation of cells which are at risk from thermal runaway.

Improper Storage

Storing wet cells beyond the manufacturer’s recommended duration promotes sulfation, and decreases cell capacity and life.

Misapplications

Batteries are commonly designed for a specific use. If the battery is not designed for a given application, it might not meet its life or performance expectations.