Voltage characteristics of lithium iron phosphate battery
The voltage characteristics of lithium iron phosphate battery (LiFePO4 battery) include rated voltage, charge cut-off voltage and discharge cut-off voltage, as follows:
1. Rated voltage
The standard value is 3.2V, which is based on the stable electrochemical characteristics of lithium iron phosphate material during charging and discharging.
2. Charging voltage range
Charging cut-off voltage: usually 3.6V~3.65V, exceeding this voltage may damage the battery life.
Recommended charging strategy: constant current and constant voltage charging method, constant current in the initial stage (to avoid large current shock), constant voltage in the later stage (to prevent overcharging), the voltage is recommended to be controlled at 3.55V~3.70V, and the optimal value is 3.60V~3.65V.
3. Discharge voltage range
Discharge cut-off voltage: The lower limit is 2.0V~2.5V, but in actual applications, it is recommended not to be lower than 2.2V~2.5V to avoid deep discharge damage.
Emergency threshold: When the voltage drops below 3.0V, the internal resistance of the battery increases sharply, the power output decreases sharply, and charging is required in time.
4. Relationship between voltage and power (SOC)
Non-linear characteristics: The voltage changes little in the high power range (such as 3.6V~3.8V at 100% SOC), and changes significantly in the low power range (such as 3.0V~3.1V at 20% SOC).
Management suggestions: Accurate monitoring is required through the battery management system (BMS) to avoid relying on voltage alone to judge power.
5. Safety and material advantages
Lithium iron phosphate batteries are not prone to thermal runaway when overcharged or at high temperatures due to their stable olivine structure (P-O bond), and are safer than lithium cobalt oxide batteries.
