Picture 1 48V/400Ah Li-ion Battery Pack Dimension Drawing
Picture 2 48V/400Ah Li-ion Battery Pack
2.1 System working principle
3. System working principle see picture 3.
Picture 3. 48V/400Ah Li-ion Battery Pack System Working Principle
2.2 Battery Management System
The battery management system has protection functions in case of overcharging, over discharging, overheating, excess current, short-circuit and so on. The battery pack will cut off power output in case of emergency. Should the capacity exceed 500A, the battery pack will shut down.
The management system has a display screen that monitors battery pack status information. It displays SOC information such as working voltage, charging and discharging current, etc.
When powered the BMS will perform a self-check to ensure all levels are normal. If all levels are normal the system will switch on the pre-charge contactor and then switch on the charge and discharge contactors.
A power diode is connected in parallel on the charge and discharge contactor for uninterrupted power supply from the battery pack. When charging and the battery voltage reaches the upper limit protection value, the charging contactor is disconnected. In this instance the battery pack is discharged externally by the diode connected to the charging contactor. When discharging and the battery voltage reaches the lower limit – below the protection value, the discharge contactor is disconnected, and the battery pack is charged by the freewheeling diode connected in parallel to the discharge contactor.
- If the BMS detects 3 function beyond the specification it will disconnect
- If cells over vault the BMS will disconnect
- In discharge state, if there is a three-level alarm the BMS will disconnect the discharge contactor;
- In state of charge, if there is a three-level alarm the BMS will disconnect the charge contactor;
- If the alarm sounds the BMS needs to be powered off and restarted before being released;
(4）BMS 4.3 LCD，SOC The BMS is equipped with a 4.3-inch LCD to display the state of battery SOC voltage and current relay and alarm state.
The battery pack uses the same power port for charging, discharging and 2 contactors;
The battery pack has 4 temperature detection points