Genset Starting Education Module #4

Lead-Acid Battery Strengths, Weaknesses, and Best Practices

Optimize performance and lifespan with strategic use of lead-acid batteries for gensets

Lead-acid batteries are among the most commonly used for genset engine starting due to their affordability and wide availability. However, their performance and reliability are highly dependent on proper maintenance and usage strategies. Unlike other battery technologies, lead-acid batteries have unique characteristics that make them prone to sudden failure at the end of their lifespan, which can lead to operational downtime if not managed proactively.

Key Characteristics of Lead-Acid Batteries

• Strengths

• Readily available and low in cost compared to other battery technologies.
• Well-suited for applications with consistent replacement schedules.

• Weaknesses

• Prone to sudden failure at the end of their lifespan.
• Sensitive to charging conditions and maintenance, which can cause premature failure if neglected.

• Strategic Use

• Treat lead-acid batteries as consumables and replace them on a regular schedule to avoid unexpected failures.
• Ensure proper charging and maintenance to maximize performance and avoid failures even in newly installed batteries.

A detailed understanding of these characteristics allows operators to implement proactive maintenance schedules and replacement strategies, ensuring genset readiness when it matters most.

Summary of strengths and weaknesses of lead-acid start batteries 

Ni-Cd Battery Strengths, Weaknesses, and Strategic Use

Maximize reliability with robust, long-lived Ni-Cd technology designed for critical applications

Nickel-Cadmium (Ni-Cd) batteries offer superior durability and a long operational lifespan compared to lead-acid batteries. Their inherent robustness makes them a preferred choice for applications requiring high reliability. However, their unique characteristics necessitate specialized strategies for maintenance and charging to ensure optimal performance.

Key Characteristics of Ni-Cd Batteries:

1. Strengths
   • Highly robust and long-lasting, far exceeding the lifespan of lead-acid batteries.
   • Do not fail suddenly, providing a more predictable end-of-life performance.
   • Suitable for critical applications where reliability is paramount.
2. Weaknesses
   • Higher initial cost compared to lead-acid batteries.
   • Not readily available at local distributors, leading to potential delays in replacement during cell failures.
3. Maintenance and Replacement Strategies
   • In the event of a cell failure, users may:
     • Jump out the faulty cell to maintain functionality.
     • Deploy a temporary lead-acid battery until a replacement cell arrives.
   • Require a well-defined commissioning charge to meet performance specifications as outlined in the manufacturer’s installation and operation manual.

Charging Considerations for Ni-Cd Batteries:

• Some variants are more challenging to fully charge² than lead-acid batteries due to lower recharge efficiency.³
• User manuals for certain Ni-Cd types specify:
  • Two-rate charging as mandatory for achieving specified performance.⁴
  • Battery chargers with automatic boost charging after discharge are essential to meet operational standards.
• As with lead-acid batteries, correct charging and diligent maintenance are critical to ensure long-term reliability.

Proper implementation of best practices and an understanding of the unique requirements of Ni-Cd batteries allow operators to maximize their strengths while addressing potential challenges effectively.

Summary of strengths and weaknesses of Ni-Cd start batteries 

Summary of Key Points

1. Lead-acid battery: 
• Strengths include that it is readily available, is made in standard sizes, and is low cost.
• Weaknesses include sudden failure at end of life, loss of life when hot, loss of performance when cold, and short shelf life. 
• The most successful strategy to achieving reliable engine starting with lead-acid starting batteries is to regularly replace them well ahead of the date of expected failure. 

2. Nickel-cadmium battery: 
• Strengths include inherently robust design and construction, no sudden failure mechanism, long service life and relatively long shelf life. 
• Weaknesses include higher initial cost and larger footprint than lead-acid, and lower availability of replacements. 
• The most successful strategy to achieving reliable operation with nickel-cadmium is committing to use Ni-Cd batteries in the first place, then continuing to maintain them.  
 

References

1. Defined as time sitting idle in a warehouse after last charge. Shelf life is shortened by high ambient temperature. 
2. Pocket plate Ni-Cd technology is more difficult to charge than newer Sintered PBE or fiber plate Ni-Cd technology.
3. Recharge efficiency of pocket plate Ni-Cd batteries is around 70%, meaning that the charger must deliver at least 140% of the ampere-hours (AH) withdrawn from the battery before the battery is fully recharged. The recharge efficiency of very shallowly discharged batteries is even lower because replacing the last AH of capacity is always more difficult than replacing the first AH when the battery is discharged. See SENS Genset Starting Education Module #6: Battery Charging Basics for additional information. 
4. Two-rate charging is the most effective way to reduce charging time. Ideally, two-rate charging temporarily increases charging voltage above the normal float voltage setting during initial battery recharge. This is called “boost charging”. Excess voltage applied to the battery compensates for voltage lost to the battery’s internal resistance. Operating at the higher boost voltage allows the battery to accept the charger’s maximum current longer than it would at float voltage. A correctly engineered charger automatically reduces the charger’s voltage to the correct float voltage value when the battery reaches full charge. See SENS Genset Starting Education Module #6: Battery Charging Basics for additional information.