Why choose Lifepo4 battery ？
Lithium iron phosphate batteries are characterized by high safety, high rate charge-discharge characteristics and long cycle life. The literature shows that the charging condition is 1C rate charge to 3.65V, and then transfer to a constant voltage until the current drops to 0.02C, and then discharge to the cut-off voltage 2.0V at 1C rate, the battery capacity is still 80% of the initial capacity after 1600 cycles.
PS: charge and discharge rate = charge and discharge current / rated capacity; for example: when the battery with a rated capacity of 100Ah is discharged with 20A, the discharge rate is 0.2C. The battery discharge C rate, 1C, 2C, 0.2C is the battery discharge rate: a measure of the speed of discharge. The used capacity is discharged after 1 hour, called 1C discharge; after 5 hours, it is called 1/5 = 0.2C discharge. Generally, the battery capacity can be detected by different discharge currents. For 24AH batteries, 2C discharge current is 48A, 0.5C discharge current is 12A.
The charge and discharge characteristics are also relatively stable. When discharging at different rates of 0.5C, 1C, and 3C, the discharge capacity drops by less than 5%. The voltage has a large stable platform during the discharge process. The performance of electric vehicles under high power demand conditions such as rapid acceleration and high speed. The more stable the voltage, the better the performance of the vehicle. In addition, this can also explain why the endurance of the electric vehicle will be weakened when driving at high speed. During output, the actual discharge capacity will decrease.
Lithium iron phosphate batteries also have good fast-charging characteristics, under 3C rate charging conditions, they can charge 55% in 15 minutes, and charge capacity exceeds 95% in 30 minutes. Note that this is a laboratory condition. In addition, it is only a single battery of 20Ah and a nominal voltage of 3.65V, which cannot be compared with a battery pack with a voltage of 100Ah or more and a voltage of about 400V. The charging power of the two differs by more than 100 times.
In addition to long life and excellent charge and discharge performance, the biggest advantage of lithium iron phosphate batteries is their safety. The chemical properties of lithium iron phosphate are stable and the high temperature stability is good. Only 700-800 ℃ will start to decompose and face Oxygen molecules will not be released during impact, acupuncture, short circuit, etc., no violent combustion will occur, and the safety performance is high.
However, the disadvantage of lithium iron phosphate batteries is that their performance is greatly affected by temperature, especially in low temperature environments, the discharge capacity and capacity will be greatly reduced. In addition, the energy density of lithium iron phosphate is low, only the weight energy density of the battery is only 120Wh / kg, if you calculate the energy density of the entire stack, including battery management systems, heat dissipation and other components, it is even lower.