How to calculate battery charging current?

The maximum charging current of the battery is determined by three aspects: 

one is the maximum charging current of the inverter itself, the second is that the photovoltaic module is too small, and the third is the maximum charging current allowed by the battery. 

Under normal circumstances, the charging current of the battery = photovoltaic module power * MPPT efficiency / battery voltage, if the module power is 5.4kW, the efficiency of the controller is 0.96, and the battery voltage is 48V, then the maximum charging current = 5400*0.96/48= 108A, the mains charging is basically calculated according to the maximum charging current of the inverter. If the maximum charging current of the inverter is 100A, this current will be limited to 100A, and then it will depend on the maximum charging current of the battery. The charging current of the acid battery is generally 0.2C, which means that a 12V200AH battery has a maximum charging current of 200*0.2=40A, so it needs to be connected in parallel to meet the current of 100A. Now lithium batteries, there are 48V100A versions, you can also choose .

How to calculate battery discharge current？

The maximum discharge current of the battery is also determined by three aspects: one is the maximum discharge current of the inverter itself, the second is the load is too small, and the third is the maximum discharge current allowed by the battery.

Under normal circumstances, the discharge current of the battery is determined by the load. The discharge current of the battery = load power/battery voltage * inverter efficiency, if the load power is 3kW, the battery voltage is 48V, and the inverter efficiency is 0.96, then this When the maximum charging current = 3000/(48*0.96) = 60A, it should be noted that the charging and discharging capacity of the battery may be different. For some lead-carbon batteries, the discharge current can reach 1C. When the solar energy storage system is running normally, if there is light, the current of the battery may not be calculated according to the above formula, and the current of the battery should be less, because it is possible that the photovoltaic and the battery can supply power to the load at the same time.