A battery balancing circuit and a portable power tool

By employing a battery balancing circuit with PMOS transistors and energy-consuming resistors in portable power tools, combined with a BMS controller, the high cost and complex circuitry issues of portable power tools are solved, achieving cost reduction and improved space utilization, while also enhancing safety and reliability.

CN224459286UActive Publication Date: 2026-07-03SHENZHEN CITY WAITLEY POWER CO LTD +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
SHENZHEN CITY WAITLEY POWER CO LTD
Filing Date
2025-07-15
Publication Date
2026-07-03

AI Technical Summary

Technical Problem

Existing passive balancing technologies for portable power tools are costly and have complex circuits, making it difficult to effectively reduce implementation costs and improve space utilization.

Method used

A battery balancing circuit is adopted, which uses a combination of PMOS transistors, energy-consuming resistors and functional resistors, combined with a BMS controller to achieve battery balancing, reducing the number of components used, especially bias resistors. The BMS controller replaces the dedicated balancing controller, and the circuit is laid out on the BMS circuit board.

Benefits of technology

It reduces the implementation cost of battery balancing circuits, improves space utilization, enhances the safety and reliability of power tools, can balance batteries during charging and resting, and reduces the number of components used.

✦ Generated by Eureka AI based on patent content.

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Abstract

This application provides a battery balancing circuit and a portable power tool. The battery balancing circuit includes multiple individual balancing modules, each corresponding to a specific battery. Each individual balancing module includes a PMOS transistor, a power-dissipating resistor, and a functional resistor. The source of the PMOS transistor is connected to the positive terminal of the battery, and its drain is connected to the negative terminal of the battery through the power-dissipating resistor. The functional resistor has a first terminal connected to the source of the PMOS transistor, and a second terminal connected to both the first pin of the BMS controller and the gate of the PMOS transistor. The negative terminal of the battery is also connected to the second pin of the BMS controller. The first and second pins are adjacent pins. When the first pin outputs a high level, the PMOS transistor is turned off, and the functional resistor acts as a sampling resistor. When the first pin outputs a low level, the functional resistor acts as a bias resistor for the PMOS transistor, and the PMOS transistor is turned on. This application reduces implementation costs compared to existing technologies.
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