The 5. 0Ah ARC Lithium Battery is now equipped with an upgraded fuel gauge. The new built-in indicator lights lets you see how much run time you have left. The ARC Lithium battery technology is the industry's most advanced; equipped with patented Keep Cool Cell Technology, which keeps the cells cool and prolongs the life of the battery. The EGO 700W Turbo Charger monitors and controls each cell in the battery pack to control temperature for maximum battery life. The active cooling fan system and advanced communication with the battery supports rapid charging without overheating. The rapid recharge capability ensures limited downtime with any EGO 56V ARC Lithium battery