Milwaukee M12™ 4.0Ah REDLITHIUM™ Battery (M12 B4)

Milwaukee M12™ 4.0Ah REDLITHIUM™ Battery (M12 B4)

When compact tools are pushed harder and run longer, the battery behind them matters. The Milwaukee M12™ 4.0Ah REDLITHIUM™ Battery is built for professionals who need extended runtime from their M12™ tools without stepping up to heavier platforms. It delivers the confidence to work longer, faster, and with fewer interruptions throughout the day.

Powered by REDLITHIUM™ battery technology, the M12 B4 provides up to 2x more runtime, up to 20% more power, and up to 2x longer battery life compared to earlier lithium-ion batteries. This makes it ideal for demanding tasks where smaller batteries fall short — from repetitive fastening and cutting to sustained installation work.

At the core of the battery is REDLINK™ digital overload protection, an intelligent system that continuously monitors performance to prevent overloading, overheating, and over-discharge. Combined with individual cell monitoring, this ensures each cell charges and discharges evenly, maximising efficiency and extending the overall life of the battery and your tools.

Built for real site conditions, the M12 B4 features an integrated welded frame construction with shock-responsive separators, helping protect the battery from internal damage caused by drops, vibrations, and everyday wear. It’s also engineered to perform reliably in extreme temperatures down to –20°C, making it a dependable choice for year-round indoor and outdoor work.

As part of the Milwaukee M12™ system, this 4.0Ah battery is compatible with over 120 M12™ cordless tools, giving you a scalable power solution that grows with your kit. It’s an ideal upgrade from lower-capacity packs, a reliable replacement battery, or a high-runtime spare to keep downtime to a minimum.

Key Features & Benefits

• 4.0Ah REDLITHIUM™ battery for extended runtime

• REDLINK™ digital overload protection safeguards tools and battery

• Individual cell monitoring for balanced charging and longer life

• Durable welded frame construction resists drops and vibrations

• Reliable performance in temperatures down to –20°C

• Compatible with the full Milwaukee M12™ cordless system

Ideal For

• Professional tradespeople

• Longer-running M12™ applications

• Users upgrading from 2.0Ah batteries

• Anyone needing extended runtime without added bulk

What’s Included

• 1 × Milwaukee M12™ 4.0Ah REDLITHIUM™ Battery (M12 B4)