What Is And What Causes Battery Degradation?

Dec. 05, 2023

Battery Specifications :

The initial aspect to consider is the rated capacity, measured in kilowatt-hours (kWh). This signifies the amount of energy the battery can store, which diminishes over time. Warranties typically acknowledge this degradation, often guaranteeing around 60% of the rated capacity after a decade of service. Additionally, there's surge capacity or C rating, representing the maximum energy the battery can deliver simultaneously. This factor is sometimes overshadowed by the inverter's peak capacity in kilowatts (kW).


Signs and Symptoms:

As a battery ages, subtle changes in its grid-connected performance may go unnoticed. The reasons for this lie in the management of lithium batteries by an electronic layer, specifically a Battery Management System (BMS). This system ensures that the battery remains within the optimal temperature and charge parameters, concealing the degradation process.

For instance, unlike a car's starting battery, your house battery system has a permanent connection to the main grid. If the battery struggles to meet demands, the grid intervenes, allowing hybrid systems with poor surge ratings to compensate.

Monitoring Battery Health Over Time:

Regular monitoring reveals the overall energy storage capacity of the battery. For example, a 15kWh battery, when new, might reach 100% state of charge at noon. However, as it ages, it may fill up faster and provide shorter usage durations, indicating a decline in performance.


Consider these factors when sizing your battery to account for potential degradation over time.

Factors Affecting Battery Life:

Temperature plays a critical role in battery life. Anything electrical generates heat, particularly batteries due to chemical reactions.Especially in hot climates, keeping the battery cool is crucial for its lifespan.Batteries have both cycle life and shelf life, making proper usage essential. Lithium cells function optimally between 20% and 90%, but BMS designs often avoid extremes to enhance longevity.

Impact of Battery Size on Long-Term Performance:

Choosing the right battery size is paramount. Deep discharges should be avoided to prevent warranty voidance. Modern hybrid packages undergo complex engineering decisions by the factory, while traditional off-grid systems are specified by the installer.


Assessing Battery Specifications Conservatism:

Manufacturers may employ conservative battery specifications to ensure durability and performance. Warranty terms, performance guarantees, and pricing are crucial indicators of a battery's true capabilities. Assessing warranty coverage is essential, as it reflects the manufacturer's confidence in their product.

In summary, understanding and managing battery degradation involve careful consideration of specifications, monitoring performance, and addressing factors like temperature and sizing for optimal longevity.

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