The Makita BL1850 B 18V, 5.0Ah Li-ion Genuine Makstar Battery is ideal for professionals and DIYers alike. The demanding applications you take on every day are also demanding on your cordless tools and batteries. You rely on your tools, so Makita created STAR Protection Computer Controls™. STAR Protection is communication technology that allows the tool and battery to monitor conditions and exchange data in real time! This helps to protect against Overloading, Over-Discharging and Over-heating. High-drain applications require maximum battery power, Makita tools and batteries are engineered for industrial applications, but sustained peak demand can overload the tool. However, Makita’s STAR Protection Computer Controls™ allow the battery and tool to communicate and protect your tool and battery by cutting power when put under abnormally high current draw. Lithium-ion batteries are engineered for longer, sustained performance, but running a battery until it’s “dead” empty can damage the cells. STAR Protection monitors this battery charge capacity, and if the battery is too low to complete the application it will cut power in order to extend battery life. Extreme heat is the enemy of all batteries. It can make them charge slower, damage their cells, and reduce battery life. Makita STAR Protection Computer Controls™ monitors battery heat during operation. If the battery reaches a certain level of heat it will cut power to the tool.