1. Application analysis of lithium iron phosphate battery in the communication industry
In recent years, people have paid more and more attention to the technological progress and application status of new energy-saving and environmentally friendly batteries. Lithium iron phosphate battery is a lithium-ion battery with good safety performance, high energy volume and wide application at this stage.
The application in the power industry has highlighted many advantages. Whether it can be gradually applied to the communication industry through the technical improvement of the production enterprise, the answer is yes.
First of all, it can be applied to the power supply system of base stations with low power, because the battery capacity required in this type of equipment room is small, the equipment operating environment in the equipment room is relatively harsh, the AC mains is unstable, and the power outages are frequent and long. IMt is inconvenient to maintain equipment or generate electricity after a power outage for maintenance personnel.
These characteristics determine that batteries with a wide temperature range, fast charging performance and long service life should be selected. Rack-mount lithium battery has these advantages.
Since the application of the battery pack in the communication industry is a long-term float charging system, which is completely different from the charging and discharging system in the power industry, if the existing lithium iron phosphate battery for power is directly used in the communication industry, the following main problems should be solved.
2. The protection value of the discharge termination voltage of the lithium iron phosphate battery for communication
Since the capacity of the lithium iron phosphate battery is basically zero when it is discharged to a voltage of 2.5V, and its open circuit voltage (OCV) curve is steeper than that of the lithium manganate battery at the initial stage.
In order to protect the battery, it is recommended that the discharge termination protection voltage of the BMS system of the lithium iron phosphate battery is set to 2.7V, and the discharge termination voltage of 16 batteries in series is 43.2V, which is not only in line with the existing usage habits of the communication industry, but also more conducive to the recovery of the capacity of the lithium iron phosphate battery.
3. The setting of the charging voltage of the lithium iron phosphate battery for communication
Since the output voltage adjustment range of the switching power supply system in the communication industry is generally -43.2 to -57.6V, the average charging voltage of traditional lead-acid batteries is generally set to 57V, while the average charging voltage of lithium iron phosphate batteries is generally required to be 57.6V.
Therefore, when the lithium iron phosphate battery is used in the switching power supply system, engineering and maintenance personnel are required to adjust and adapt the switching power supply equipment.
4. How to use lithium iron phosphate batteries in the communication industry?
The lithium iron phosphate battery used in the communication industry should first meet the relevant requirements of the existing high-frequency switching power supply system (-48A or 240V) or modular uninterruptible power supply system in the communication industry for battery management, that is, it is used under the premise of not changing the existing functions of the high-frequency switching power supply or the UPS power supply system.
Therefore, it is necessary for lithium battery manufacturers to manufacture products suitable for the communication industry according to the characteristics of the communication industry. First, 16 mature batteries with a single-cell capacity of 40Ah should be connected in series to form a “basic sales unit” (40Ah51.2A).
Then a unique lithium iron phosphate battery management system (BMS) is developed for this unit. This BMS should include charge and discharge management of each battery and various protection functions for this unit.
However, the protection function used in the power industry cannot be completely copied, especially the protection function of interrupting discharge should be cautious. The battery used in the communication industry has been in a floating charge state for a long time, and the battery temperature is rarely below 0 °C, and there is basically no problem of inability to charge;
The rectification system in the communication industry has the function of limiting the overcharge current of the battery pack (generally O.25C10), and the overcharge current value of the lithium iron phosphate battery is much larger than that of the valve-regulated sealed lead-acid battery, so there is no need to limit the overcurrent value of the lithium battery separately.
However, when the voltage of a battery in the basic sales unit (40AH51.2V) reaches 3.8V, the charging of this unit should be terminated immediately;
In order to protect the lithium iron phosphate battery from over-discharge, the BMS must detect the voltage of each battery in the basic sales unit (40Ah51.2V).
When the voltage of any one is 2.7V, the discharge of this unit should be terminated immediately, because the discharge time of the lithium battery from 2.7V to 2.5V is very short, and it may be better to set it to 2.7V.