The Shimano SM-BTR1 is the Di2 external battery. While external battery mounts have changed over the years, the battery has stayed the same. The only external battery is still the SM-BTR1. Most bikes these days will be equipped with internal batteries such as the BT-DN110.
It weighs about 70g, has a rated capacity of 500 mAh / 3.7 WH and a rated voltage of 7.4 V. You charge the battery by taking it out of the bike and putting it in the SM-BCR1 external battery charger.
When storing the battery away for a long period, remove it when the indicator is at the half-way level (for the FLIGHT DECK) or when the green indicator is flashing (for the SM-EW79A) in order to prolong its useful life. It is recommended that you check the condition of the battery about once every half a year.
Note that this older battery can be made synchro-shift and BluetoothLE compatible. You will need to use it in combination with the current generation BM-DN100 battery mount.
Details & Specifications
|Shimano model number:||SM-BTR1|
|E-Tube Port type:||SD50|
|Component series:||Non-series components NON (All)|
|Downloads:||SM-BCR1 User Manual|
External Battery Mount User Manual