External LEM DHAB current sensor connector 750A for Battery Management System (Tiny BMS) can hold 150 A discharging current just for very short pulse current spikes (Table 2.1). For higher current capability, external current sensor and contactors should be used. Currently supported current sensor is LEM DHAB S – 133, which is a dual-range sensor, with measurement range up to ±750 A. Lower range measures up to ±75 A and is used for higher accuracy measurement of low current. Switching of ranges is done automatically by Battery Management System (Tiny BMS) itself. External current sensor to Battery Management System (Tiny BMS) system should be connected once at the setup stage of the battery pack.
Note: External current sensor is critical Battery Management System (Tiny BMS) and battery application component. After external current sensor has been connected to Battery Management System (Tiny BMS), BMS must be restarted by the user to confirm that external current sensor is used for battery application, otherwise Battery Management System (Tiny BMS) internal current sensor will be used for current measurement. For complete guide how to properly connect and use external current sensor refer to Chapter 4.
Connector part number, that mates with Battery Management System (Tiny BMS) board is PHR-4 made by JST and connector, that mates with LEM current sensor, part number is 1-1456426-5 made Tyco Electronics. When connecting external current sensor attention must be taken to the positive current direction, providing that high current wire is passed through current sensor in correct direction. Tiny BMS treats positive current from battery positive terminal to load / charger positive terminal.
Note: External current sensor should only be used along with external relay / contactor for load or charger control, when high current capability is needed. When external relay / contactor is used for load / charger switching high current path bypasses the Tiny BMS board and the internal current measurement is not possible.
Battery Management System (Tiny BMS) LEM external current sensor configuration External current sensor can be connected only to the 150 A high power Battery Management System (Tiny BMS) hardware version. Current sensor is the essential component of the battery application, therefore due to the safety reasons there is an important sequence how to connect and use LEM external current sensor.