What is the nominal number of cycles (e.g. 6000)? How long does it take to decay to 80% capacity? ‌

‌In energy storage battery systems, the nominal number of cycles and capacity decay rate are key indicators for measuring battery life. 

1、 What does the nominal number of cycles: 6000 mean? ‌

The nominal number of cycles refers to the number of times a battery is charged and discharged under laboratory conditions (25 ℃ constant temperature, fully charged and discharged) until its capacity drops to 80% of its initial value.

For example, lithium iron phosphate batteries (commonly used for energy storage) have a nominal cycle count of 3000-6000 times. If charged and discharged once a day, the theoretical lifespan is about 8-16 years. Ternary lithium batteries have lower cycle times (about 500-1500), but higher energy density, making them suitable for short cycle applications.

2、 How long does it take to decay to 80%?

Assuming a certain energy storage battery has a nominal cycle of 6000 times, its actual use is affected by the following factors:

Charging and discharging frequency: If charged and discharged once a day, the theoretical lifespan is approximately 6000 days (about 16 years). If charged and discharged twice a day (such as during power grid peak shaving), the lifespan can be shortened to about 8 years.

Charge and discharge depth: Full charge and discharge (100% depth) will accelerate aging. If only 50% of the battery is used each time (such as from 80% to 30%), the lifespan can be extended to more than 12000 times.

Calendar lifespan: Even if not in use, the battery will naturally age, and lithium iron phosphate batteries typically experience a capacity decay of less than 80% after 12-15 years.

Actual conclusion: A battery with 6000 cycles, under reasonable use (charging and discharging once a day, temperature control), will decay to 80% capacity in about 10-15 years.

6000 cycles represent the ideal lifespan of the laboratory, which is actually influenced by usage habits.

The time to decay to 80%: about 10-15 years (shallow charging and discharging once a day), if frequently fully charged or in high temperature environments, it may be shortened to 6-8 years.

Choosing a reliable battery system, combined with scientific management strategies, can maximize the economic value of energy storage equipment.