The Makita 18V, 5.0 Ah Li-ion Genuine Makstar Battery is ideal for professionals & DIYers alike. The demanding applications you take on every day are also demanding on your cordless tools & batteries. You rely on your tools, so Makita created STAR Protection Computer Controls™. STAR Protection is communication technology that allows the tool & battery to monitor conditions & exchange data in real time! This helps to protect against Overloading, Over-Discharging & Over-heating. High-drain applications require maximum battery power, Makita tools & batteries are engineered for industrial applications, but sustained peak demand can overload the tool. However, Makita’s STAR Protection Computer Controls™ allow the battery & tool to communicate & protect your tool & 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, & 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, & 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.