Makita 21V Battery Protection Replacement Board with Balanced BMS & Temperature Control

Keep your Makita 21V power tool batteries running safely and efficiently with this high-quality Battery Management System (BMS) Protection Replacement Board. Designed specifically for 5-cell (5S) lithium-ion battery packs, this board features built-in cell balancing and temperature control using 5MOS 3-alloy construction — delivering reliable, long-lasting protection for your valuable battery packs.

Whether you're rebuilding a worn-out battery or upgrading your existing protection circuit, this replacement board is an essential component for DIY battery repair and maintenance.

Key Features

Compatible with: Makita 21V 5S lithium-ion battery packs
Balanced Protection: Active cell balancing ensures all cells charge and discharge evenly for maximum pack longevity
Temperature Control: Built-in thermal protection prevents overheating and safeguards your battery cells
5MOS 3-Alloy Design: High-quality MOSFET configuration for stable and efficient power management
Overcharge & Over-discharge Protection: Automatically cuts off current at unsafe voltage levels
Short-Circuit Protection: Instantly disconnects in the event of a short circuit
Lightweight: Single set weight of just 30g — minimal added bulk to your battery pack
Voltage Range: USB 5–20V DC compatible
Packaging: Individually bagged for safe delivery

Product Specifications

Accessory Type: Battery Protection / BMS Board
Applicable Voltage: 21V (5S Li-ion)
Weight: 30g per unit
Battery Included: No
Charger Included: No
Origin: Made in Mainland China

Who Is This For?

This replacement board is ideal for electronics hobbyists, power tool repair technicians, and DIY enthusiasts who want to restore a Makita 21V battery pack to full, safe working condition without purchasing an entirely new battery. Replacing a faulty BMS board is a cost-effective way to extend the life of your battery pack.

Safety & Electronics Resources

For general safety guidance on lithium-ion batteries and consumer electronics, visit the U.S. Consumer Product Safety Commission (CPSC) – Lithium-Ion Battery Safety.

Frequently Asked Questions

Q: Is this Makita 21V BMS replacement board compatible with all Makita battery models?

A: This board is designed for Makita 21V 5-cell (5S) lithium-ion battery packs. Please verify your battery pack's cell count and voltage rating before purchasing to ensure compatibility with your specific Makita battery model.

Q: What does the "balanced protection" feature do on this battery protection board?

A: The balanced protection (BMS balancing) function monitors the voltage of each individual cell in the battery pack and redistributes charge evenly across all 5 cells. This prevents any single cell from overcharging or over-discharging, which significantly extends overall battery life and maintains consistent performance.

Q: Does this board include temperature protection for Makita batteries?

A: Yes. The built-in temperature control feature monitors the heat levels within the battery pack and will cut off the circuit if temperatures rise to unsafe levels, protecting both the battery cells and your power tool from heat-related damage.