Aircraft batteries are vital components responsible for powering ignition systems, emergency lighting, avionics, communication units, and backup power systems. Marathon-type batteries, known for their endurance and high energy output, remain widely used in a variety of aircraft platforms. However, even the most durable aviation batteries are vulnerable to failure if not maintained, inspected, and handled properly. Preventing these failures is fundamental for operators who aim to avoid AOG events, unexpected downtime, and safety-related complications during critical flight operations.

This comprehensive guide explains the essential steps, maintenance practices, and technical insights that operators must understand to ensure reliable performance and long service life from Marathon aircraft batteries.

Understanding the Importance of Battery Failure Prevention

In aviation, a battery is far more than a simple power source. It supports multiple safety-critical systems, especially during engine start and emergency scenarios. A sudden failure can result in:

• Engine start delays or failures

• Reduced backup power for emergency avionics

• Faulty communication equipment

• Unexpected maintenance interruptions

• Potential in-flight complications

• Costly AOG delays

Because the aviation environment exposes batteries to vibration, temperature extremes, and high power demands, preventing battery failure is not just recommended—it is mandatory for maintaining operational safety.

1. Establish a Rigorous Inspection Routine

Inspection is the foundation of battery failure prevention. Operators should implement both quick checks and detailed scheduled inspections.

Daily or Pre-Flight Inspections

1. These include visual checks conducted by pilots or ground staff:

• Examine for swelling, cracks, or case deformation

• Look for electrolyte residue or signs of leakage

• Check the security of terminals and connectors

• Verify proper ventilation in the battery compartment

• Inspect wiring for burns, chafing, or corrosion

Even minor defects can escalate into a battery failure under load, so early detection is critical

Scheduled Technical Inspections

Carried out by certified technicians, they include:

• Capacity testing

• Load testing under controlled conditions

• Internal resistance evaluation

• Electrolyte measurement and adjustment (if applicable)

• Torque checks on all connections

• Assessment of chemical stability

Routine inspections identify issues long before they become operational risks.

Follow Correct Charging and Discharging Practices

Charging discipline is one of the most crucial aspects of maintaining Marathon-type aircraft batteries. The majority of premature battery failures result from incorrect charging procedures.

Avoid Overcharging

Overcharging generates excessive internal heat, which leads to:

• Plate corrosion

• Loss of electrolyte

• Chemical imbalance

• Risk of thermal runaway

Heat damage shortens battery life drastically and can trigger sudden failure.

Avoid Undercharging

Undercharged batteries are prone to:

• Sulfation buildup

• Reduced power output

• Unstable voltage under load

• Shortened cycle life

Maintaining proper charging ensures batteries retain their designed energy density and operational reliability.

Use Approved Charging Systems

Charging equipment must meet aviation specifications and match the chemistry of the Marathon battery.

Using non-compatible chargers can cause permanent internal damage. Understanding battery specifications is especially important when handling high-performance cells such as those in the CBS28-1 category, which demand precise charging parameters.

Maintain Proper Battery Chemistry Conditions

Marathon-type aircraft batteries rely on a delicate chemical balance. Changes in temperature, humidity, or maintenance habits can affect this internal chemistry.

Factors That Influence Battery Chemistry

• Exposure to extreme temperatures

• Improper charging curves

• Prolonged storage without charging

• Vibration and mechanical shock

• Contaminated or low electrolyte levels (for applicable designs)

Why Chemistry Knowledge Matters

A battery’s ability to deliver power under load depends on chemical stability. When this balance is disrupted:

• Internal resistance increases

• Capacity drops

• Cells become unbalanced

• Voltage output becomes inconsistent

Technicians trained in aviation battery chemistry can identify these issues long before they lead to operational failure.

Control Corrosion to Maintain Performance

Corrosion is a major silent threat to aircraft battery systems. Even minor corrosion can disrupt the electrical path, leading to poor power delivery or sudden loss of function.

Common Causes of Corrosion

• Electrolyte leakage

• Moisture exposure

• Salty or humid environments

• Poorly maintained terminals

• Inadequate protective coatings

Best Corrosion Prevention Practices

• Clean terminals regularly using approved solutions

• Apply protective coatings that resist acid fumes

• Keep connectors properly torqued

• Inspect vents to prevent acid mist accumulation

• Ensure battery compartments are dry and ventilated

Corrosion prevention not only improves conductivity but also prolongs the overall life of the battery.

Conduct Regular Capacity Testing

A battery may appear externally healthy but still fail to deliver sufficient power. Capacity testing is the most reliable method for understanding true battery health.

Benefits of Capacity Testing

• Confirms the battery’s energy output

• Detects internal chemical degradation

• Helps diagnose increased resistance or aging cells

• Determines whether reconditioning or replacement is needed

Operators who rely on capacity testing typically see fewer unexpected battery failures.

Implement Correct Storage Protocols

Battery storage conditions directly impact performance, especially for aircraft that experience seasonal or extended downtime.

Storage Best Practices

• Store batteries in a cool, dry, temperature-controlled environment

• Fully charge before placing into storage

• Perform periodic top-up charges based on manufacturer guidelines

• Avoid exposure to direct heat or freezing temperatures

• Keep units upright to avoid internal imbalance

Proper storage prevents chemical separation, loss of electrolyte, and internal corrosion.

Track Battery Age and Plan Timely Replacement

All batteries have a finite service life. Even with perfect maintenance, chemical and mechanical degradation occur naturally over time.

Factors to Track

• Total number of cycles

• Hours in service

• Capacity decline trends

• Abnormal internal resistance increases

• Temperature exposure history

Replacing a battery before failure protects both the aircraft and the operator from unexpected maintenance delays.

Rely on Certified Aviation Maintenance Professionals

Aviation batteries must only be serviced by qualified and certified maintenance personnel. Certified shops have:

• Proper diagnostic equipment

• Aviation-approved testing benches

• Knowledge of battery chemistry and flight standards

• Correct procedures for reconditioning

• Documentation and tracking for airworthiness compliance

Choosing skilled professionals is one of the most effective ways to maintain high performance and safety.

Conclusion

Preventing Marathon aircraft battery failure requires a combination of disciplined inspections, correct charging habits, corrosion control, chemistry awareness, and the use of certified maintenance services. Operators who follow these guidelines significantly reduce the risk of AOG events, extend battery lifespan, and maintain dependable safety performance across every phase of flight.

Proper battery care doesn’t just protect equipment—it protects the aircraft, the crew, and every mission that depends on uninterrupted power.