Shimano Dura-Ace Di2 7970 SM-BTR1 BatteryShimano Dura-Ace Di2 7970 SM-BTR1 Battery. At a feather light 71g, the DI2 battery pack powers your entire system. On average, the battery can hold a charge for 1000 miles. Your current battery charge level can be checked through the front wire kit.689228289635
