How Are Aircraft Batteries Maintained

Batteries provide the initial power needed to start an aircraft’s engines, support onboard systems during ground operations, and serve as a safeguard if generators fail in flight. Because they occupy such important roles, gradual wear, chemical degradation, and environmental stresses must be carefully managed. To keep batteries operating as intended, technicians should follow structured maintenance programs, which we will cover in this guide.

Regular Inspections and Pre-flight Checks

The first step in keeping batteries in optimal shape is performing an inspection before every flight. During these checks, operators carefully look for signs of cracked cases, loose connections, corrosion around terminals, fluid leaks, unusual odors, or discoloration, all of which might indicate functional issues. They also confirm that the battery is securely mounted within its compartment, since vibration or shifting during operation can cause damage.

Maintenance and Testing Cycles

While pre-flight checks are an imperative strategy for catching immediate issues, long-term battery performance relies on structured maintenance cycles. These schedules are generally influenced by how often the aircraft is flown and the type of battery in service. For example, in general aviation, many operators conduct detailed inspections at least once a month or every two weeks if the aircraft is in heavy use.

Moreover, a capacity test is usually performed during annual or 100-hour intervals, involving discharging the battery at its rated current until the cut-off voltage is reached while recording how long the battery sustains the load. If the unit cannot provide at least 80 percent of its rated capacity, it is considered unairworthy and must be serviced or replaced.

In addition to capacity checks, operators also perform full-service procedures that may include hydrometer readings, recharging cycles, and electrolyte inspections, ranging in frequency from monthly to annually. During these deeper maintenance practices, issues flagged in pre-flight inspections are addressed directly through repairs depending on the extent of the damage.

Type-Specific Maintenance Procedures

Nickel-Cadmium (Ni-Cd) Batteries

Nickel-cadmium batteries are valued for their durability, but they require strict oversight because they are prone to overheating and thermal runaway. To maintain stability across all cells, technicians perform an equalization charge, a process in which the battery is charged at a controlled current to bring every cell to the same state of charge.

After the charge, a discharge test is performed. If results show that only a small number of cells are underperforming, they may be replaced individually to extend the battery’s usefulness. However, when a larger portion of cells deteriorates, the battery is retired altogether.

Additionally, Ni-Cd batteries consume electrolyte during normal charging, so distilled water levels need to be monitored and adjusted periodically. Vent inspections are equally important, as blockages can allow pressure to build inside the case and compound the risk of thermal runaway.

Lead-Acid Batteries

A practice unique to lead-acid chemistry is the use of a hydrometer to measure electrolyte specific gravity (SG), which gives a direct indication of both charge state and overall health. This measurement is often paired with voltage checks taken after charging, which confirm whether the battery is balanced and capable of delivering consistent performance to guide further servicing as needed.

Meanwhile, flooded lead-acid battery variants require periodic checks of electrolyte levels and adding water when required to keep plates fully submerged. In contrast, sealed or valve-regulated lead-acid (VRLA) batteries eliminate the need for electrolyte servicing. Though, they require precautions like proper ventilation, avoiding deep discharge cycles that accelerate sulfation, and maintaining charge with float charging systems during long idle periods.

Lithium-Ion Batteries

Lithium-ion batteries represent the most modern technology in aviation power systems, and their servicing leans heavily on advanced monitoring. Most units incorporate battery management systems (BMS) that continuously track voltage, current, and temperature, with replacement schedules typically determined by recorded service time or cycle counts.

Storage Practices

Upkeep alone is not enough to keep batteries in an ideal state; proper environmental control is also vital. For batteries installed on an aircraft, exposure to excessive heat can accelerate chemical degradation and internal corrosion, whereas extreme cold can temporarily reduce power capacity.

For batteries that are not in use or placed in long-term storage, cool, dry, and well-ventilated areas are necessary to prevent deterioration. Operators also maintain these batteries by performing top-up or maintenance charges every four to six weeks. With lead-acid types in particular, these periodic charges prevent sulfation, a condition where lead sulfate crystals form on the plates and reduce effective capacity.

Browse Ready-to-Purchase Aircraft Batteries on Alpha Aerospace Parts

In summary, aircraft batteries depend on a structured process to keep them safe and ready to perform. Ultimately, even with diligent upkeep, batteries have finite lifespans. For instance, lead-acid types tend to be replaced every four to six years depending on conditions and charging practices, while nickel-cadmium batteries can remain in service for eight to ten years with proper maintenance. Furthermore, extensive damage or an inability to maintain 80% of its rated capacity usually requires immediate retirement.

If you find yourself in need of replacement batteries, Alpha Aerospace Parts can connect you with quality, standards-compliant options sourced from trusted manufacturers. As a platform owned and operated by leading distributor ASAP Semiconductor, we pride ourselves on offering competitive procurement solutions for thousands of products, all while catering to the distinct requirements of each customer. We look forward to serving your operations with our unrivaled selection and services, so be sure to connect with our team at your earliest convenience.