BMS 3S 20A Protection Board

3S 20A Lithium Battery BMS Protection Board

Suitable for 3 series 18650 batteries. It does not charge batteries. It is for battery protection. It takes on the balancing task.

     The 3S 20A BMS Protection Board protects an 11.1V / 12.6V lithium battery pack made of 3 series-connected 3.7V Li-ion (18650 etc.) or LiPo cells against overcharge, over-discharge, overcurrent and short circuit. It delivers 20A continuous current and suits up to 252W output and charging power. When the voltage of any cell rises to 4.25V it cuts the charge, and when it falls to about 2.5V it cuts the current to the load.

     The board measures 59mm x 20mm x 3.4mm, weighs 4.4gr and has a long, thin shape; it fits beside or under a 3-cell 18650 pack. It carries 4 power MOSFETs and a current sense resistor. The cell connections are printed on the board as 0V, 4.2V, 8.4V and 12.6V; the load and the charger are connected to the ⊕ and ⊖ input / output pads at the end of the board.

     This board does not charge the battery, it only protects it. A 3S lithium charger with 12.6V output is needed to charge the pack. After a short circuit the protection releases automatically with a delay.

Key features:

     20A continuous current: The board carries 20A continuous current; it suits 3S packs feeding loads such as 12V LED lighting, speakers, small motors and cordless tools.

     Per-cell voltage protection: The voltage of each cell is monitored separately; charging is cut when a cell reaches 4.25V and discharging is cut when it falls to about 2.5V.

     Overcurrent and short circuit protection: The pack is disconnected when the current rises to about 40A or the output is short circuited; after a short circuit the protection releases automatically with a delay.

     Easy connection: The cell connection pads are printed on the board as 0V, 4.2V, 8.4V, 12.6V; the load and the charger share the same ⊕ / ⊖ pads.

     Thin and light board: With 59mm x 20mm x 3.4mm size and 4.4gr weight it sits on or beside a 3-cell 18650 pack.

Features:

• Product type: 3-cell series (3S) lithium battery protection board (BMS / PCM)
• Model: 3S 20A BMS
• Suitable battery: 3 series-connected 3.7V Li-ion (18650 etc.) or LiPo cells; 11.1V, 12V, 12.6V packs
• Continuous working current: 20A
• Maximum output / charging power: 252W
• Charging voltage: 12.6V - 13V
• Overcharge detection voltage: 4.25V ± 0.05V (per cell)
• Overcharge release voltage: 4.1V - 4.2V (per cell)
• Over-discharge detection voltage: about 2.5V (per cell; 2.3V - 3.0V depending on seller)
• Over-discharge recovery voltage: about 3.0V - 3.2V (per cell)
• Overcurrent protection: about 40A
• Short circuit protection: Yes, delayed automatic recovery
• Charging function: None (does not charge the battery, only protects it)
• Structure: 4 power MOSFETs, current sense resistor
• Connection pads: 0V, 4.2V, 8.4V, 12.6V (cells), ⊕ and ⊖ (load and charger input / output)
• Operating temperature: -40°C - +50°C
• Storage temperature: -40°C - +80°C
• Color: Green
• Dimensions: 59mm x 20mm x 3.4mm
• Weight: 4.4gr

Usage information:

• Connect the cells according to the diagram on the board: the - terminal of cell 1 to 0V, the junction of cells 1 and 2 to 4.2V, the junction of cells 2 and 3 to 8.4V, the + terminal of cell 3 to the 12.6V pad. Make the wiring in order starting from 0V.
• Connect the load and the charger to the ⊕ and ⊖ input / output pads at the end of the board; the pack is then charged and discharged only through these pads.
• If there is no voltage at the output after connection, connect a 12.6V charger to the ⊕ / ⊖ pads once to activate the board; the output then turns on.
• For high current loads use wires of sufficient cross-section on the ⊕ / ⊖ and 0V / 12.6V connections; reduce the load current if the board is in a poorly cooled place.

Areas of use:

•  Battery: 3S 18650 and LiPo battery packs
•  Drill: 12V cordless drill battery pack
•  Screwdriver: cordless screwdriver
•  Modem: 12V battery UPS for modem and router
•  Speaker: portable 12V speaker and amplifier
•  Camping: camping lamp and 12V LED lighting
•  Solar: small storage packs charged by solar energy
•  RC: RC car and boat batteries
•  Robot: 12V robot and vehicle projects

Precautions:

•  Make the wiring strictly according to the diagram (0V, 4.2V, 8.4V, 12.6V). Wrong connection damages the protection IC.
•  The board does not charge the battery. Use a 3S lithium charger with 12.6V output; do not connect a higher voltage adapter.
•  The board is for 3 cells in series (3S, 11.1V / 12.6V) only. It is not used with 2S, 4S packs or LiFePO4 (3.2V) cells.
•  Use cells of the same capacity, internal resistance and state of charge; do not mix good and worn cells in the same pack.
•  With high inrush motors such as drills, the board cuts the output if the starting current exceeds the overcurrent protection threshold. 20A continuous current requires good cooling.

Package contents:

•  1 Piece 3S 20A BMS Protection Board
•  Note: Battery, charger and cable are not included in the package.