With the launch of Dura-Ace 9100 came new firmware offering road riders Synchronized Shifting options between front and rear derailleurs. A short while later this technology was made available to Ultegra 6800-series and Dura-Ace 9000-series riders who have the latest Di2 battery. Synchronized shifting is also available on mountain bikes and GRX.
The new battery (BT-DN110/BT-DN110-a) contains a memory chip that can handle the processing power required to deal with the multiple shift patterns and customizations that Synchronized Shifting brings, offering you the choice to suit your gear positioning to your personal riding style.
In order to charge this battery just connect your SM-BCR2 to either your bar-end/frame junction or below-the-stem mounted junction box and plug it into a power socket or laptop. Note that the USB port you plug the charger into should supply at least 1A.
If you’re planning on putting this battery in your seatpost you will probably also want a seatpost battery mount or battery holder. You can easily find those on Amazon, Chain Reaction Cycles or eBay, All major manufacturers make them.
Sometimes these Di2 seatpost battery holders work so well that they make it next to impossible to remove the battery. In this case you can usually get the battery out by taking a J-bend spoke and inserting it into the seatpost, hooking the bent part of the spoke behind the battery holder. You should then be able to pull it out of the seatpost.
I wrote a separate article on doing just that, remove a stuck Di2 battery from a seatpost.
It is possible to mount this battery outside the frame, if your bike or seat post does not support internal mounting. You can use the external case SM-BTC1 to mount it outside the frame. It also doubles as a 5-port Junction B.
There are two different versions of the BT-DN110 Internal battery available, the BT-DN110 and BT-DN110-A. The latter is grey, not black, newer and slightly better built. The functionality of both batteries is the same. If you already have the BT-DN110 don't bother upgrading to the BT-DN110-A, you will not notice any difference.
With the release of DURA-ACE R9250 Shimano will also introduce a new battery, the BT-DN300. This battery will probably still be a seatpost battery and look similar to this BT-DN110. It will use a different wiring standard though - EW-SD300.
Details & Specifications
|Shimano model number:||BT-DN110|
|E-Tube Port type:||SD50|
|Component series:||Non-series components NON (All)|
|Downloads:||SM-BCR2 User Manual|
BT-DN110 User Manual