# BMS module 4S with balance, 40A, 16.8V

> 4S BMS module with passive balance, for Li-Ion cells 3.7V (e.g. 4x18650), charge voltage 16.8V. Maximum discharge current 40A, maximum charge current 10A, balance current 50mA. Dimensions 60.5 x 45.2 x 3.4mm. Includes CD (charge finished) and FD (discharged) pads for status indication. Reference 33525.

- Page: https://sigmanortec.ro/en/bms-module-4s-with-balance-40a-168v
- Price: 12.06 RON
- Availability: In stock; 1-2 zile
- Reference: 33525 · EAN: 5948630643769
- Category: Electronic components > Modules for Batteries > BMS Boards
- Specifications: Technology: Lithium Ion; Load voltage: 16.8VDC; sway: Yes; Number of cells: 4S
- Package (shipping data): 0.011 kg
- Updated: 2026-09-23
- Shop: [Sigmanortec.ro](https://sigmanortec.ro/en/llms.txt)
- Prices: RON, VAT included; prices and stock as of 2026-10-22 01:33 (Europe/Bucharest)

## Description

4S BMS module for protection and management of 3.7V Li-Ion batteries, ideal for 4x18650 packs and tool batteries. Provides passive cell balancing for uniform charging and better life, supports up to 40A when discharging and 10A when charging, operates at 16.8V and includes CD and FD signals for status indication.
Protection module for charging 4S lithium battery packs (example 4x18650), type BMS (Battery Management System) for cells with a nominal voltage of 3.7V (4.2V when fully charged).
It can be used for creating dedicated batteries for tools.
This BMS is equipped with a cell balancing function, increasing the durability and performance of the battery used. All cells will be charged to the same level. Balancing is achieved by applying a resistor to the line with a higher voltage than the others, thus allowing the cells with a lower charge to catch up with the cells that have a higher voltage.
Balancing is a function that corrects small differences that may occur during charging, but a large difference between cells cannot be corrected by the internal balancing function. Use only batteries that are identical in specifications, capacity, and internal resistance.
The BMS has two pads, marked CD and FD. CD represents the signal indicating that the charging is finished, FD represents the signal indicating the discharge state.
Specifications:
Version: with Balancing
Battery charging voltage: 16.8V
Maximum discharge current: 40A (with good heat dissipation)
Maximum charging current: 10A (check battery specifications)
Balancing: Passive (through resistor)
Balancing current: 50mA
Dimensions mm: 60.5 x 45.2 x 3.4mm
Failure to follow the wiring diagram when installing components and making connections will result in module damage.