BM3451 [Four-cell Lithium Battery Protection Board 6MOS Upgrade Version]

======WARNING======
The BOM (Bill of Materials) should be based on the schematic diagram! Do not use the BOM
in the project description directly! The BOM should be based on the schematic diagram! Do not use the BOM in the project description directly
! The BOM should be based on the schematic diagram! Do not use the BOM in the project description directly!
Please follow the CC-BY-NC-SA 3.0 open-source license. This project is for learning and research purposes only and is prohibited for commercial use.
Electronics exchange groups: 232586710, 345731137. This is
 
a four-cell battery protection board with equalization designed based on the BYD BM3451TNDC-T28A battery management chip.
The form factor is adapted to the stacked arrangement of four 21700 batteries, featuring a small size and minimal space consumption.
It includes an equalization indicator light, which illuminates during battery equalization, allowing you to clearly see which battery is being equalized.
This protection board is fully functional, providing protection against overcharge, over-discharge, overcurrent discharge,
short circuit, and overcurrent charging by detecting the voltage and charging/discharging current of each battery cell. The BM3451 offers a battery capacity balancing function to eliminate capacity differences between cells in the battery pack, extending battery life.
The board also features optional high-temperature protection; it shuts off output when high battery temperature is detected and restarts output once the battery temperature drops.
This system is suitable for four-string battery packs with a nominal 3.7V and a fully charged 4.2V ternary lithium-ion battery combination. The
overcharge detection voltage is 4.250V
, the overcharge release voltage is 4.190V
, the over-discharge detection
voltage is 2.800V, the over-discharge release voltage is 3.000V,
the overcurrent protection current is 50A (default) ,
the balancing start
 
voltage is 4.190V, and the overcurrent detection voltage is 100mV. 100 / set current = current sensing resistor value. For example, 100mV / 20A = 5mΩ.
To connect the protection board to the battery, first solder the battery negative terminal pad, then solder B1, B2, B3, and the balancing node in sequence, and finally solder the battery positive terminal pad. Do not reverse the soldering order.
 
 
The MOSFETs will heat up during prolonged high-current operation; therefore, heat sinks must be used for heat dissipation.