Types and Compatibility of Shimano Di2 Batteries

Types and Compatibility of Di2 Batteries

Di2 Battery Determines the Di2 Generation

Shimano’s electronic shifting system, Di2, has a component known as the “master unit” which manages the system. The master unit is not located in the STI levers, derailleurs, or junction boxes, but is instead housed in the “battery (or battery mount).”

In internally mounted systems, the master unit is integrated into the battery, while in externally mounted systems, the master unit is housed in the battery mount that holds the battery.

Therefore, the choice of battery determines the compatible generation of Di2.

The SM-BTR1 battery from the 7970 series is compatible with the external batteries from the BTR/DN100 series.

Di2 from the BTR/DN100 series is compatible with its parts, but there are differences in wireless communication standards. The BTR series battery/battery mount uses “ANT+ only,” while the DN100 series battery/battery mount supports both “Bluetooth & ANT+.”

For more details about the generations of Di2, please refer to the article below.

Differences Between Internal and External Mounting

Shimano’s Di2 system has different methods of mounting the battery depending on the generation.

The first generation of DURA-ACE Di2 (7970) only supports “external mounting.” The following BTR and DN100 series for 10/11-speed Di2 support both “internal and external mounting.” The latest 12-speed Di2, the DN300 series, only supports “internal mounting.”

Differences in Required Accessories and Parts

The method of battery mounting also affects the charging method and system setup for the Di2 system.

For external mounting, a “dedicated charger” and either a “PC connection device or wireless unit” are required.

For internal mounting, the BTR/DN100 series can use the PC connection device as the setup tool, so only one device is needed. For the latest DN300 series, the rear derailleur has Bluetooth and a charging terminal, so you only need to purchase a dedicated USB cable to handle both charging and system setup.

Thus, the required Di2 accessories depend on the battery you choose.

However, for the BTR/DN100 series, if a Bluetooth wireless unit is introduced, Di2 system setup can be done wirelessly via Bluetooth, so whether the battery is internal or external, only a battery charger is required. This results in little difference in cost.

How to Choose Di2 Batteries

The Type of Battery You Can Choose Depends on the Compatible Frame

Where you mount the battery depends on the bike or frame you are installing the Di2 system on.

For road bikes, the “internal mounting” on the seat post is highly versatile. However, if you have a gravel road bike or MTB with a dropper seat post, internal mounting won’t be possible, so you’ll need to use an external mount.

For external mounting, a hole in the frame is required to route the electric wires inside, so you need to choose a compatible frame.

Thus, start by selecting a Di2 battery that can be mounted on your specific bike system or frame.

Narrowing Down the Compatible Batteries by Di2 Generation

Once the mounting method for the Di2 battery is determined, select the compatible Di2 generation and corresponding battery.

For external mounting, you can choose from Di2 10/11-speed, while for internal mounting, you can select from Di2 10/11/12-speed options.