1.6 Operating and Storage Temperature
Lithium batteries exhibit broad temperature tolerance, but the expected operating and storage environments must be clearly defined before deployment. Select battery types with appropriate characteristics for specific requirements, and implement heating or cooling measures if necessary to maintain optimal operating conditions. Never operate lithium battery products beyond their specified temperature range. Verify during design validation that actual operating temperatures remain within safe limits.
1.7 Interface
Battery packs connect to the UPS electrical components via various interfaces. The battery pack incorporates connectors compatible with the electrical system to facilitate connection to the UPS. Beyond electrical compatibility, connections must be secure and reliable, capable of withstanding at least 100 insertion/removal cycles without deformation or connection failure.
Battery connectors must be protected during transportation to prevent short circuits and other issues.
1.8 Other
Lithium battery cells and packs must comply with industry standards and obtain necessary certifications. They must meet transportation, environmental, and safety requirements for sales and application in specific regional markets.
The lithium battery pack itself should be covered by third-party product liability insurance.

2. BMS Protection Coordination

   The Battery Management System (BMS) is a circuit device within lithium battery packs that monitors physical parameters such as cell voltage, current, and temperature, and provides protection for the battery pack. It is an indispensable component for the safe, stable, and reliable operation of lithium battery packs.
   Beyond power circuit connections, the UPS communicates with the battery pack's BMS through two methods to coordinate protection functions: dry contact signals and serial port data communication.
   Figure 2.1 UPS-Lithium Battery Pack Communication Coordination Signal Chain
   2.1 Dry Contact Signals
   The UPS provides a charge/discharge control interface, defining two fundamental dry contact signals for interfacing with the lithium battery. These signals receive dry contact commands from the battery pack to control whether the UPS's internal charger initiates charging or discharging of the lithium battery.
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   Charge/Discharge Control Interface Location

   Charge/Discharge Control Interface Definition

   Interface definitions are as follows:
   C1/C2: Charging dry contact input signals, non-polarized. Open-circuit input indicates charging enabled; short-circuit input indicates charging stopped.
   D1/D2: Discharge dry contact input signals, non-polarized. Open-circuit input indicates discharge enabled; short-circuit input indicates discharge disabled.
   2.1.1 Charging Dry Contact Signals
   Battery Pack BMS Output Dry Contact Signal 1 is defined as the charging dry contact signal. A normally open condition indicates charging is permitted, while a normally closed condition indicates charging is prohibited.
   When an overcharge alarm occurs within the battery pack—such as voltage reaching 3.5V/Cell (in any cell) or over-temperature events—charging must cease. At this point, charging dry contact signal 1 actuates (turning from normally open to normally closed).
   After charging stops, the battery voltage may decrease due to balancing or natural decay. When the voltage drops to 3.38V/Cell and other abnormalities are reset, the alarm is cleared, and dry contact signal 1 returns to normally open.