With the release of the semi-wireless DURA-ACE R9250 groupset, Shimano will also introduced a new battery: BT-DN300. This battery was first mentioned in FCC documents, as well as the RD-R9250 rear derailleur.
The BT-DN300 battery connects to the rest of the Di2 system using the EW-SD300 wires.
Will it be backward compatible? Probably. You would have to use the EW-AD305 adapter to connect it to older components though.
Just like the previous generation BT-DN110, the BT-DN300 is also a seatpost mounted battery.
The Ultegra R8170 and DURA-ACE R9270 series are semi-wireless. Both derailleurs are connected to the battery using EW-SD300 wires, but the shifters communicate wirelessly. This battery probably has three ports, allowing you to connect wires to it without having to use any junction boxes.
Details & Specifications
|Shimano model number:||BT-DN300|
|E-Tube Port type:||SD300|
|Component series:||DURA-ACE R9200 (Road)|
|Downloads:||BT-DN300 User Manual|
BT-DN300 Dealer Manual