BMS charge controller 4S - 40 A, Li-ion battery 18650

Product Overview

• Charge controller and discharge controller for lithium-ion batteries in one module
• Maximum current of 40 A during charging and discharging
• Protects the battery through automatic voltage monitoring and shutdown
• Operating voltage of 3.0 to 4.2 V for individual cells
• Connection via PCB terminals, no plug required
• Balancing lead can optionally be used for multi-cell battery packs

Product Description

This charge and discharge controller module protects lithium-ion batteries from overcharging and deep discharge. It operates directly at the cell voltage and automatically disconnects the battery when a cell has been charged above 4.2 V or discharged below 3.0 V. The maximum current of 40 A determines which applications are possible; for higher-power applications such as electric vehicles and stationary storage systems with higher current flows, this module is insufficient.

The module is soldered directly to the battery terminal or connected using PCB terminals, without requiring an additional plug. For multi-cell battery packs, the cells can be balanced using an optionally connected balancing lead. The connections lie flat on the circuit board, allowing for compact enclosures, but also making visual inspection after soldering more difficult.

The module is typically used in portable battery storage systems for solar panels, power tools, or DIY power banks. This type of protection circuitry is also used in battery-backed power supplies for emergency lighting. In all cases, the charging current must be limited by a separate charger; the module only regulates the maximum voltage and maximum discharge current.

Operation requires the battery voltage to remain limited to 3.0 to 4.2 V. For multi-cell battery packs, the voltage of each individual cell must also remain within the permissible range; otherwise, the protection only responds to a cell that is incorrectly charged or has shifted due to aging. The discharge current under load is damped by the counter-inductance of the circuit, so brief current peaks above 40 A are possible without damaging the module.

Safety Information

Lithium-ion batteries can cause fires or release toxic gases in the event of a short circuit or damage; defective or swollen batteries must not be charged further. The module is intended exclusively for building prototypes and for testing and development purposes, and is not designed for operation in household electrical circuits or in products intended for general sale. If there is any uncertainty regarding the safety of the battery pack or correct wiring, consult a qualified electrician before commissioning.

Scope of Delivery

• 1x 4S charge controller for 40A Li-ion battery, 14.8 V / 16.8 V