Battery Lifetime and Maintenance

Battery Lifetime

Batteries have a defined lifespan that can be measured in different ways depending on their application. For batteries that undergo regular charging and discharging cycles, such as those used in photovoltaic systems, the number of charge/discharge cycles is a key measure of lifetime. This indicates how many cycles the battery can go through while maintaining a specific fraction of its original capacity.

The chemical reactions that occur within batteries make them susceptible to degradation over time. While catastrophic failures are possible, the gradual decrease in battery capacity due to charge/discharge cycles is the primary factor influencing battery lifetime. Typically, battery lifetime is expressed as the number of cycles it can undergo while retaining its original capacity. In contrast, for systems with infrequent charge/discharge cycles like uninterruptible power supplies, battery lifetime is often specified in years. Incorrect usage can accelerate battery aging and reduce its usable cycles.

Maintenance Requirements

The type of battery used significantly impacts its maintenance needs. Some batteries undergo reactions that produce gases and other byproducts, leading to changes in volume. Batteries that experience volume changes are harder to seal and may require additional chemical components, like water, to compensate for gas evolution. Hermetically sealed batteries, which do not exchange materials with their surroundings, have lower maintenance needs compared to batteries with interacting elements. While small primary batteries are usually hermetically sealed and maintenance-free, secondary batteries like lead-acid batteries demand a strict maintenance regimen.

Failure Modes

Batteries can degrade gradually or fail catastrophically due to various reasons such as shorts, electrode material degradation, freezing, and increased resistance. Understanding these failure modes is crucial for ensuring battery longevity and safety.

Battery Safety and Disposal

Many battery systems, including those in renewable energy applications, contain corrosive or hazardous chemicals. It is essential to adhere to safety regulations specific to each battery type. Additionally, batteries can produce high currents, posing safety risks. In lead-acid battery systems, hydrogen evolution is a potential concern. Proper disposal of batteries is crucial as they often contain toxic or corrosive materials that can harm the environment if not handled correctly.