What are the factors influencing the life cycle of the powerwall 20 kwh? The proper charging system has an important influence on the discharge capacity of the battery. If the charging depth is shallow, the discharge capacity will be reduced accordingly. If the battery is overcharged, it will affect the chemical active substances of the battery and cause irreversible damage, reducing the battery capacity and powerwall life cycle. Therefore, it is necessary to select appropriate charging rate, upper limit voltage and constant voltage cut-off current to ensure optimal charging efficiency and safety and stability under the condition of achieving charging capacity. At present, power lithium ion wall mounted battery mostly use constant current constant voltage charging mode. By analyzing the constant current and constant voltage charging results of lithium iron phosphate system and ternary system batteries under different charging currents and different cut-off voltages, it can be seen that: (1) when the charging cut-off voltage is constant, the charging current increases, the constant current ratio decreases, the charging time shortens, but the energy consumption increases; (2) When the charging current is fixed, the constant current charging ratio decreases with the decrease of the charging cut-off voltage, and the charging capacity and energy are decreasing. To ensure the battery capacity, the charging cut-off voltage of lithium iron phosphate battery shall not be lower than 3.4V. It is necessary to balance the charging time and energy loss, and select the appropriate charging current and cut-off time.
The consistency of individual SOC largely determines the discharge capacity of the battery pack, while balanced charging makes it possible to achieve similar initial SOC platforms for individual discharge, which can improve discharge capacity and discharge efficiency (discharge capacity/group capacity). The equalizing mode during charging refers to the equalizing of the 20 kwh power wall battery during charging. Generally, the equalizing starts when the single battery voltage reaches or is higher than the set voltage. Overcharging is prevented by reducing the charging current.
According to the different states of the single battery in the battery pack, through the battery pack equalizing charge control circuit model and the equalizing circuit to fine tune the charging current of the single battery, a equalizing charge control strategy that can not only realize the rapid charging of the battery pack, but also eliminate the impact of the inconsistency of the single battery on the cycle life of the battery pack is proposed. Specifically, through the switch signal, the overall energy of the lithium ion battery pack is supplemented to the single battery, or the energy of the single battery is converted to the overall battery pack. During the charging process of the battery pack, by detecting the voltage value of each single battery, when the voltage of the single battery reaches a certain value, the equalization module starts to work. Shunt the charging current in the single battery to reduce the charging voltage, and the separated current will feed back the energy to the charging bus through module conversion to achieve the purpose of equalization