3S 12V Lithium Battery BMS Protection Board

3S 8A 12V Lithium Battery BMS Protection Board

Suitable for 3 series 18650 batteries.

     The 3S 8A BMS is a triangular protection board made for cordless drill and screwdriver batteries consisting of 3 series-connected 3.7V Li-ion cells (18650), 10.8V - 11.1V nominal and 12.6V fully charged. The board carries a DC-004 type DC charging socket and 3 bent metal contacts that fit the battery case terminals; therefore it can be fitted directly in place of the failed protection board of 12V cordless drill and screwdriver batteries.

     The board monitors the voltage of each cell; it cuts charging when a cell exceeds 4.25V and cuts discharging when it drops below approximately 2.5V. It also cuts the current on overcurrent and short circuit. Working current is at most 8A, instantaneous current limit is 40A; charging is done at 12.6V - 13V voltage and 1A - 2A current. Cell connection is made through the B+, B2, B1 and B- pads; the red and yellow wires fitted on the board are soldered to the cells.

Key features:

     Shape suited to drill batteries: The triangular board and 3 bent metal contacts are made to fit the case of 12V cordless drill and screwdriver batteries. The top contact is charge negative (C-), the side contacts are output positive and output negative.

     DC charging socket on board: The DC-004 type socket is on the board; the battery is charged directly through this socket with a 12.6V lithium charging adapter.

     Per-cell protection: The voltage of the three cells is monitored separately. Charging is cut when any cell exceeds 4.25V and discharging is cut when it drops below approximately 2.5V.

     8A working, 40A instantaneous current: Chosen for the working current of small 12V drills and screwdrivers; it allows the short current at motor start up to the 40A limit and cuts the current above this limit and on short circuit.

     Wires fitted: Red and yellow wires for the cell connection come fitted on the board; only the cell terminals need soldering during assembly.

Features:

• Product type: 3 cell series (3S) lithium battery protection board, cordless drill battery type
• Model: 3S 8A BMS (board marking KXYC-3S-CMD1)
• Suitable cells: 3 series 3.7V Li-ion cells (18650)
• Pack voltage: 12V class (3S): 10.8V / 11.1V nominal, 12.6V fully charged
• Charging voltage: 12.6V - 13V
• Charging current: 1A - 2A
• Working current: 8A maximum
• Instantaneous current limit: 40A (overcurrent protection trips at this limit)
• Overcharge protection: 4.25V ±0.05V (per cell)
• Over-discharge protection: approximately 2.5V (per cell)
• Short circuit protection: yes
• Overcurrent protection: yes
• Charging input: DC-004 type DC charging socket on the board
• Battery case contacts: 3 bent metal contacts (input / output +, output -, charge -)
• Cell connection terminals: B+, B2, B1, B- solder pads
• Fitted wires: red and yellow cell connection wires
• Color and shape: Blue PCB, triangular board
• Dimensions: approximately 35.6mm x 33.3mm x 22.6mm
• Weight: approximately 9gr

Usage information:

• Connect the cells in series. Connect B- to the negative of cell 1 (0V), B1 to the junction of cells 1 and 2 (4.2V), B2 to the junction of cells 2 and 3 (8.4V), B+ to the positive of cell 3 (12.6V). Make the connections according to the diagram in the picture.
• The device (drill, screwdriver) is powered from the positive and negative output contacts on the sides. For charging, plug a lithium charging adapter with 12.6V output into the DC socket; charging voltage must not exceed 13V and charging current must not exceed 2A.
• When replacing the protection board of an old battery, first note the contact layout of the old board; seat the contacts of the new board in the same places in the battery case.

Applications:

•  12V cordless drill battery repair and protection board replacement
•  Screwdriver batteries (12V cordless)
•  Cordless tool batteries (12V)
•  Building 3S 18650 Li-ion battery packs
•  Speaker (portable) batteries
•  LED lighting batteries (12V)
•  Camping lamp batteries
•  Small backup power batteries for modem and router
•  Battery packs charged from a DC socket for small 12V devices

Precautions:

•  Working current is at most 8A. High-power drills draw more current; this board is for small 12V drills and screwdrivers. A higher-current 3S protection board is needed for high current.
•  A drill draws high current at start; ordinary 18650 cells may not run the drill. Use high discharge current (power type) cells.
•  The board does not charge the battery and does not limit charging current. Use a 12.6V lithium charging adapter, not a fixed 12V adapter. This also applies to charging through the + and C- contacts; an old Ni-Cd / Ni-MH charging cradle is not used.
•  Connecting the cell terminals (B1, B2) in the wrong order can damage the protection IC. Measure the voltage of each terminal before soldering.
•  The board is for 3S (3 cells); it is not used in 4-cell 16.8V packs.

Package contents:

•  1 pc 3S 8A BMS Protection Board
•  1 pc DC charging socket ( Assembled )
•  3 pcs metal contact ( Assembled )
•  2 pcs cell connection wire ( Assembled )
•  Note: Batteries, battery case and charging adapter are not included in the package.