SM-BTR1
Brand: Shimano
External lithium-ion battery of the early Di2 generations, carried on a mount screwed to the frame's bottle-cage bosses. Shimano quotes 530 mAh at 7.4 V for 71 g, and a full charge in about 1.5 hours on the SM-BCR1 desk charger. It carries no E-Tube port: the mount — SM-BMR2, later BM-DN100 — handles the electronic link. Dropped from the Shimano catalogue during 2023.
| Type | Electronic shifting accessory |
|---|---|
| Model years | 2011–2023 |