The most important factors for maintaining the life of lithium batteries

The life and capacity of lithium-ion (LFP) batteries depend greatly on usage factors and operating environment, and these batteries are widely used in solar energy systems, whether connected to the grid or not. These batteries have a specific energy capacity measured in kilowatt hours (kWh), and their life span usually ranges from 8 to 15 years, during which they can lose between 20% and 30% of their original capacity. This degradation depends on charge and discharge cycles, temperatures, and depth of discharge (DOD), as shallow discharge at a low cycle rate extends the life of the battery.

1.State of Charge (SOC) and Depth of Discharge (DOD):

State of Charge (SOC) indicates the percentage of charge remaining in the battery at any given moment, while Depth of Discharge (DOD) expresses the amount of capacity that has been used in a specific cycle. For example, if 70% of a 10 kWh battery’s capacity is used, the state of charge will be 30% and the depth of discharge will be approximately 70%. Generally, it is best not to discharge the battery below 20% to ensure that there is spare capacity for emergencies and to keep the battery within warranty.

2.Battery State of Health (SOH):

The state of health (SOH) is a measure of the percentage of the battery’s original capacity remaining. Over time, this number decreases at a rate of 1% to 4% per year. This natural decline—known as capacity fade—depends on several factors, including temperature, charge and discharge rate, and depth of discharge. Example: If the state of health of a 10 kWh battery after 7 years of use is 85%, the available capacity will be 8.5 kWh. Keeping track of SOH helps identify the battery’s aging process and ensures compliance with manufacturer standards.

3.Battery End of Life (EOL):

A battery is considered to have reached the end of its life (EOL) when its capacity drops to a certain percentage of its original capacity (usually between 60% and 80%), depending on the warranty. The warranty document specifies this percentage and often guarantees that a certain percentage of capacity will be maintained after a certain number of years or a certain amount of energy production. Once EOL is reached, the battery is still usable, albeit at reduced efficiency. Some manufacturers may require the battery to be returned after reaching this stage.

Important tips to extend the life of a lithium battery

1)Avoid deep discharge of the battery: It is recommended not to discharge the battery below 20%, unless necessary. This helps extend the life and reduces the internal stress of the battery.

Avoid extreme heat and cold: High temperature (above 45 degrees Celsius) accelerates battery wear, while cold (below 0 degrees Celsius) affects its performance. It is preferable to place the battery in a moderate temperature place.

2)Full charge every period: It is preferable to charge the battery to 100% every 7-10 days to ensure cell balance, but it is better not to keep it fully charged for a long time if it is not used daily.

3)Fast and moderate charging: Fast charging may cause internal pressure and a rise in temperature, so it is preferable to charge at a medium speed.

4)Balance between performance and longevity:

Some users prefer deep discharge to get the most out of the battery, but it contributes to shortening its life. If you want optimal performance and are interested in extending the battery life, it is recommended to use limited discharge.

Following these tips can make a real difference in maintaining battery efficiency for a longer period, especially with the additional challenges we face, such as rising temperatures and increased energy consumption. It is also important to consider the costs of batteries, as investing in them is important and deserves care to maintain their efficiency for the longest possible period.

Whether you use the battery for household purposes or within a larger solar system, remember that good battery handling will lead to better performance and save you the costs of repeated maintenance and replacement!