1. Definition of cycle life
The cycle life of a battery usually refers to the number of charge and discharge cycles that a battery undergoes from the time it is manufactured until it can no longer be charged or provide effective power. For portable energy storage power supplies, each complete charge and discharge process is counted as a cycle.
2. Capacity decay
As the number of charge cycles increases, the capacity of the battery gradually decreases. This is because the chemicals inside the battery undergo redox reactions during the continuous charge and discharge process, resulting in the loss of active substances. For example, after multiple cycles of lithium-ion batteries, the crystal structure of the positive and negative electrode materials will gradually change, reducing the amount of electricity that the battery can store. Generally speaking, when the battery capacity drops to about 80% of the initial capacity, it is considered that the battery life is approaching the end.
3. Life assessment
Batteries of different types and brands vary in charge cycle life. Some high-quality lithium-ion batteries can withstand thousands of charge cycles while still maintaining a high capacity. For example, some brands of portable power station batteries may have a capacity retention rate of between 80% and 90% after 1,000 cycles. Lower quality batteries may only withstand a few hundred cycles before the capacity drops significantly.
2. Impact of performance efficiency
1. Changes in energy density
During battery use, as the number of cycles increases, the internal impedance of the battery will gradually increase. This causes the battery to generate more heat during charging and discharging, and also reduces the energy density of the battery. The decrease in energy density means that after each charge, the battery can provide less effective power, which affects the use time of the portable energy storage power supply.
2. Changes in output power
The output power of the battery is also affected by the number of charging cycles. As the battery ages, its internal resistance increases, and the output power gradually decreases when powering the device. This may affect the normal operation of some devices with higher power requirements. For example, some high-power outdoor electrical equipment may require higher output power to work properly, and when the battery output power is insufficient, the operation of the equipment will deteriorate.
3. Changes in charging efficiency
Charging efficiency is an important indicator for measuring battery performance. As the number of charging cycles increases, the battery's charging efficiency will gradually decrease. This means that in the same charging time, the battery can be charged with less electricity, or it will take longer to fully charge the battery. The reduction in charging efficiency will increase the user's charging costs and inconvenience.
