4S LiFePO4 BMS 150A Same Port Bluetooth CAN RS485 for 12V Battery Pack

What This BMS Does
The YKN BMS4S protects 4 lithium iron phosphate cells connected in series creating a nominal 12V battery. It handles both charging and discharging through the same pair of wires making installation straightforward. The board continuously monitors voltage current and temperature and disconnects the battery when any parameter goes outside safe limits.

Electrical Ratings
Maximum continuous charge current is 150A and maximum continuous discharge current is also 150A. Charging voltage must be set to 14.6V. The acceptable cell voltage range for the entire pack is 9.6V to 15V. This allows the BMS to work with standard 12V inverters chargers and loads.

Products	Technical parameters
YKN-BMS4S(Bluetooth)	Basic parameters
	Cell specifications	4 series of lithium iron phosphate cells
	Interface type	Charge and discharge are both at the same port
	Charging Voltage	14.6V
	Cell voltage range	9.6~15V
	Continuous charging current	≤150A
	Continuous discharge current	≤150A
	Consumption of running	≤25mA
	Consumption of sleep	≤300uA
	Operating temperature	-30℃~75℃
	Size (L*W*H)	160mm*95mm*25mm

Power Efficiency
While the battery is in use the BMS consumes no more than 25 milliamps. When the system detects no activity for a programmed period the BMS enters sleep mode drawing only 300 microamps. This feature prevents the BMS from draining the battery during long term storage.

Core Protection Features
The hardware logic provides instant response to dangerous conditions. Overvoltage protection triggers if any cell exceeds the preset threshold. Undervoltage protection cuts off discharge when cells become too empty. Overcurrent protection reacts to excessive charge or discharge current. Short circuit protection shuts down output within microseconds. High temperature and low temperature protection use the NTC sensors to keep the battery within safe operating limits.

Cell Balancing Mechanism
The BMS includes passive balancing that bleeds excess charge from higher voltage cells until all four cells equalize. Users can set two parameters the voltage at which balancing starts and the voltage difference that triggers balancing. Balancing can run only during charging or continuously while idle. This flexibility helps maintain pack capacity over hundreds of cycles.

Temperature Sensing
Four thermistor inputs connect to individual cells or to different locations within the battery pack. A fifth input measures the temperature of the BMS power section where the MOSFETs generate heat. The system uses this data to protect both the cells and the board itself.

Communication Protocols
Bluetooth allows smartphone connection for real time monitoring of each cell voltage pack current temperature and protection status. RS485 supports Modbus for integration with industrial controllers inverters or display panels. CAN bus connects to automotive or energy storage networks. All three options give access to the same data and allow parameter changes through the upper computer.

Additional Hardware Features
A reserve heating output can drive an external heater pad to warm cells before charging in freezing weather. A buzzer output can sound an alarm when a protection event occurs such as low battery or over temperature. Both features are optional and activated through the configuration software.

System Expansion
Multiple YKN BMS4S boards can be connected in series to build higher voltage batteries for example two BMS units with two 4S packs make 24V. They can also be paralleled to increase capacity while each BMS protects its own pack. Proper communication wiring ensures coordinated protection.