What are the functional requirements for echelon lithium iron phosphate batteries? Compared with lead-acid batteries, cascaded lithium iron phosphate batteries have certain advantages in terms of cycle life, energy density, and high-temperature performance, and various performance indicators are better than lead-acid batteries. The cascade lithium iron phosphate battery can technically meet the power backup requirements of various operating conditions in the existing network, and the cascade battery with different cycle life is suitable for different application scenarios.
What are the functional requirements for echelon lithium iron phosphate batteries?
Ladder lithium iron phosphate battery refers to the degraded use of lithium iron phosphate batteries, mainly for lithium iron phosphate battery packs. The new battery pack will decay after being used for a certain period of time, and the decay will not be enough to meet the current equipment application power requirements. But the battery is not broken. After some repairs and adjustments, it can be used on equipment that requires a lower level of power consumption. For example, the original equipment uses 200Ah, 72V, but the cascade battery is repaired and adjusted. , Only 120Ah, 62V, so it can only be applied to other electrical equipment.
The series of cascade lithium iron phosphate battery specifications can be divided into three types: embedded, floor-standing, and floor-standing box type according to the installation method. The use of cascade batteries is expected to further reduce the construction cost of base stations, and play an advantage in scenarios such as peak shaving and valley filling, and solar base stations. Create value.
1. Sleep function
The cascaded lithium iron phosphate battery should have a sleep function. During transportation, storage, or offline, the battery pack BMS should be completely disconnected; when the battery pack is transferred from the online state to the offline state, the BMS should have a screening function. The battery pack status automatically goes to sleep. When the battery pack changes from offline state to online state, BMS should be able to distinguish and automatically activate, and adjust the working state according to the power and battery pack status.
2. Electric heating function
When cascaded lithium iron phosphate batteries are used in scenes of -5°C and below, a direct current heating device should be configured (the temperature needs to be controlled and adjusted according to the actual situation), and the lithium battery pack should have a special heat dissipation design to ensure uniform heating and normal equipment jobs.
3. Charging current limit management function
The cascaded lithium iron phosphate battery should have an autonomous current-limiting charging function to ensure that the battery pack can be charged normally when the voltage is input within the working range. The charging current limit value should be set between 0.1C3 (A) ~ 0.2C3 (A), the default value is 0.2C3 (A).
4. The total charging voltage is a too high protection
The cascaded lithium iron phosphate battery should have a high total charging voltage protection function. When the charging reaches the total voltage alarm point, it will alarm, when it reaches the protection point, it will be protected and cut off. When the total voltage drops to the recovery point, the charging will be resumed.
5. The total discharge voltage is too low protection
The cascaded lithium iron phosphate battery shall have the protection function of the total discharge voltage is too low. When the discharge reaches the low total voltage alarm point, the discharge circuit should be cut off and an alarm should be given. After a period of time, the battery pack should enter sleep mode.
6. The discharge cell voltage is too low protection
The cascade battery shall have the function of protecting the cell voltage from being too low during discharging. It will give an alarm when the cell voltage reaches the warning point and protect it when it reaches the protection point. The battery shall be cut off. After a period of time, the battery shall enter sleep mode.
7. Discharge overcurrent management
The cascade battery should have the output overcurrent protection function set according to the user's needs. During the protection period, the circuit should be cut off and an alarm should be given.
8. Battery high-temperature protection function
The cascade lithium iron phosphate battery itself should have the battery's high-temperature protection function. When the battery temperature reaches the alarm point, it will give an alarm; when it reaches the protection point, it will protect and act as a cut-off; it will automatically recover after the temperature drops to a certain value.
9. Battery low-temperature protection function
The cascade lithium iron phosphate battery itself should have the battery low-temperature protection function, when the battery temperature reaches the alarm point, it will give an alarm; when it reaches the protection point, it will protect and act as a cut-off; it will automatically recover after the temperature rises to a certain value.
10. Calculation of the state of charge (SOC) of the battery pack
The cascade battery shall have a dynamic charge calculation function, and the error between the calculated value and the actual battery charge shall not exceed 5%.
11. Output short circuit protection
When a direct short circuit occurs between the positive and negative poles of the cascade lithium iron phosphate battery, the circuit should be automatically cut off and an alarm should be instantaneous. The BMS and the battery should not be damaged (including no ignition, deformation, leakage, smoke, fire, or explosion); After that, it should be able to resume work manually or automatically.
Compared with traditional lead-acid batteries, what are the advantages of echelon lithium iron phosphate batteries?
High energy density: The specific energy by weight of lithium iron phosphate battery products can exceed 130Wh
(0.2C, 25℃), and the specific energy by volume is 210Wh/L; the weight-specific energy of lead-acid batteries is 32～37Wh (0.2C, 25℃), the volume-specific energy is 70Wh/L;High-current charging and discharging performance: Lithium iron phosphate batteries can be charged and discharged quickly at a high current of 2C, and the starting current can reach more than 5C. Lead-acid batteries have no such performance now. So the charging time of lithium iron phosphate battery is short;
Green and environmental protection: Lithium iron phosphate battery does not contain any heavy metals and rare metals (the nickel-hydrogen battery requires rare metals), non-toxic (SGS certification); there is a large amount of lead in lead-acid batteries, if they are discarded, if they are not handled properly, Will still cause secondary pollution to the environment;
The cascade utilization power lithium battery has a long service life and a large number of cycles. After cascade utilization, the actual service life of 6 years and the actual cycle times of 400-2000 times can still remain theoretically, which is compared with the traditional lead-acid battery with a service life of 3-6 years, 200 The actual number of cycles is greatly improved;
Strong high-temperature resistance, lithium battery meets the use of extreme working conditions below 45℃, the current upper limit of the lead-acid battery commonly used in communication base stations is only 35℃;
The charging and discharging conversion efficiency are high, and the energy conversion efficiency of the cascaded lithium iron phosphate battery is 10% to 15% higher than that of the lead-acid battery.
Summary: The cascade battery intelligent backup system provides solutions for other industries, such as banks, hospitals, and data centers. The application of cascaded lithium iron phosphate batteries is a major innovation in the development of national strategic emerging industries such as energy conservation, environmental protection, and new energy. It has very important practical significance for promoting the development of low-carbon economy, green economy, and circular economy. It is beneficial to the country and the people.
