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

Keep your Makita 21V battery pack running safely and efficiently with this purpose-built replacement Battery Management System (BMS) protection board. Designed for 5-cell (5S) lithium battery packs, this board features 5MOS triple-alloy circuitry, built-in cell balancing, and integrated temperature control — giving your battery the protection it needs against overcharge, over-discharge, overcurrent, and thermal runaway.

Whether you're repairing a worn-out Makita battery pack or building a replacement, this drop-in board makes the process straightforward and reliable.

Made in Mainland China.

Key Features

Compatible with Makita 21V battery packs — designed as a direct replacement board
5MOS 3-alloy design — robust MOSFETs for efficient current switching and low heat generation
Balanced cell protection — actively balances cells to maximize pack lifespan and capacity
Temperature control circuit — monitors and responds to heat buildup to prevent thermal damage
Multi-layer protection — guards against overcharge, over-discharge, short circuit, and overcurrent
Lightweight & compact — single set weight just 30g; easy to fit inside existing battery housings
Voltage range: USB 5–20V DC compatible
Packing method: Individually bagged for safe delivery

Product Specifications

Compatible Voltage: 21V (5S Li-ion)
MOSFET Configuration: 5MOS 3 alloy
Cell Balancing: Yes
Temperature Control: Yes
Weight: 30g per set
Battery / Charger Included: No
Origin: Mainland China

What's in the Box

1 × Makita 21V Replacement Battery Protection Board (bagged)

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For general electrical safety guidance when working with lithium battery systems, refer to the U.S. Consumer Product Safety Commission (CPSC) – Lithium-Ion Battery Safety.

Learn more: Battery management system

Frequently Asked Questions

Q: Is this battery protection board compatible with all Makita 21V battery packs?

A: This replacement BMS protection board is designed for Makita 21V (5S lithium-ion) battery packs with balanced protection. It is recommended to verify your existing board's layout and connector configuration before installing to ensure a proper fit.

Q: What does "balanced protection" mean on this BMS board?

A: Cell balancing ensures that all individual cells within the battery pack charge and discharge at equal rates. This prevents any single cell from overcharging or over-discharging, which significantly extends overall battery pack lifespan and maintains consistent performance.

Q: Does the temperature control feature protect against overheating during charging?

A: Yes. The integrated temperature control circuit monitors heat levels within the battery pack during both charging and discharging. If temperatures exceed safe thresholds, the board will cut off current flow to prevent thermal damage or potential hazards.

Q: Does this board come with a battery or charger?

A: No — this listing is for the replacement protection board only. No battery cells or charger are included.

Made with care

Great value

Elegant design

Quality materials

This product is crafted with quality materials to ensure durability and performance. Designed with your convenience in mind, it seamlessly fits into your everyday life.

We strive to process and ship all orders in a timely manner, working diligently to ensure that your items are on their way to you as soon as possible.

We are committed to ensuring a positive shopping experience for all our customers. If for any reason you wish to return an item, we invite you to reach out to our team for assistance, and we will evaluate every return request with care and consideration.