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Why batteries need replacing

By Bobby George

• Low electrolyte levels expose the busbar and ultimately the upper portion of the plates that can cause irreversible sulphation, and can accelerate corrosion.The low electrolyte levels can be the result of lack of battery maintenance, or as a result of overcharging where fluid is lost through gassing.  As an additional problem, the acid concentration in the battery from lower electrolyte levels can cause increased corrosion of the remaining 'wet' part of plates.  Batteries with higher electrolyte volume above the plates assist in minimizing these problems, and ensuring batteries are regularly maintained when operating in harsh conditions will also prolong battery life.
• High under bonnet operating temperature.   Harsh Australian operating conditions, and increasing vehicle under bonnet operating temperatures, can cause early battery failure through a number of areas.   These conditions contribute to corrosion of the positive plate, grid growth which can result in a short circuit, and loss of plate active material.
• Vibration effects.  This can cause physical damage to battery components and often sudden failure of the battery.
  Vibration damage can include:
  -  Loss of active material from the plates, resulting in a loss of battery charge and possible short circuits.
  -  broken or cracked grid frames, causing short circuits; usually causing separator damage.
  -  perforation of the separator envelopes at the bottom where the plates sit in the battery case.  This can result in short circuits.
• Overcharging.  Where the vehicle charging system has been operating at a higher than normal voltage, the battery is subjected to virtually continuous charging.  This can result in faster grid corrosion, loss of plate active material, loss of electrolyte, plate growth and eventually disintegration of the positive plate.
• Undercharging.  This can occur when the vehicle voltage charging system is too low to fully recharge the battery.   The result is a loss of charge and irreversible sulphation of the battery.

• Grid corrosion of the Positive plates within a battery is a normal 'end of battery life' condition that is commonly caused due to higher operating temperatures, overcharging or loss of electrolyte fluid.  Of the positive and negative plates within a battery, it is the positive plates where the grid metal can completely oxidize and disintegrate due to these operating conditions.   Different alloys added to the positive grid lead can have an affect on the corrosion rate.  Antimonies lead grids generally have a higher corrosion resistance than calcium lead grids, and along with higher volumes of electrolyte above the plates, can help overcome this problem, allowing batteries to operate more successfully in Australia's harsh conditions.
• Soft Positive Plate Material ("mushy plates").  This is a condition usually resulting from high operating temperatures or overcharging.  Often, both conditions may have occurred.
• Sulphation.  This occurs when a battery stands in a partially or fully discharged state for long periods of time, or is continually undercharged.  As a result of these conditions the active lead material on the plates becomes lead sulphate which also hardens the plates.   Depending on the length of time the battery has been in this condition, the sulphation may be irreversible.  In addition, if the electrolyte level in the battery is low, the exposed part of the plates will become inactive and sulphated.  Therefore batteries with higher electrolyte levels will go a long way to reducing problems due to sulphation and assisting longer battery life.

• Broken cell to cell connection.   This is where there has been a complete failure of the intercell weld.  Weld quality is critical for reliable battery performance and good working life.  This problem is largely minimized by manufacturers like Century Yuasa Batteries and other leading manufacturers, due to accredited quality assured manufacturing processes.
• A broken busbar.  This type of failure can be caused by excessive corrosion of the busbar due to low electrolyte level in the battery.  Extensive overcharging and/or elevated operating temperatures can also lead to accelerated corrosion of the busbars leading to breakage and and open circuit.  Batteries with the capacity for higher electrolyte levels will help to ensure a longer battery life.