Shimano Dura-Ace Di2 SM-BTR1 Battery

The Shimano Dura-Ace Di2 SM-BTR1 battery is a rechargeable 7.4 volt lithium-ion battery for the Dura-Ace Di2 component system. It mounts to the harness included with the rear wire kit (sold seperately) that mounts to the downtube bottle cage bolts and sits just below the bottle cage. This means that you can still use a bottle cage and gives the battery a low center of gravity. The front wire kit (sold seperately) has a convenient battery life indicator which is activated by holding down one of the shift buttons. Green means the battery has 50% or more life, Red indicates under 50% of battery life and flashing red indicates an almost drained battery. If the battery does wear out while riding the system will stay in the gear that it dies in so you will still be able to get home. Shimano recommends re-charging about every 1,000 miles. There is no charge memory so the battery can be charged again and again at any intervals. The battery can go through 300 charge cycles without diminishing and will slightly and slowly diminish afterward. Charge time is 1.5 hours. Battery weight: 70 grams. Charger, wiring kit, and mount sold separately.