Running Shimano's wireless Di2 system means owning the EC-DN100 charger—there's no other way to charge the BT-DN320 battery that powers the XTR, Deore XT, Deore, and GRX wireless rear derailleurs. The charger isn't included with the derailleur or the battery, so if you're building a wireless Di2 drivetrain from individual components rather than buying a complete groupset kit, this is a required purchase. Having a second charger also makes sense if you want one at home and one in your travel kit.

The charging process is straightforward: remove the BT-DN320 from the derailleur by sliding off the battery cover, drop the battery into the EC-DN100 cradle, and plug the included USB-C cable into any standard USB power source. The charger draws 5V at 1.5A input and delivers 8.7V at 0.62A to the battery, taking approximately 90 minutes to fully charge a depleted BT-DN320. LED indicators on the charger show charging status—you'll know when the battery is ready without needing to check an app.

The compact dimensions (54 x 35 x 25mm) make the EC-DN100 easy to toss in a gear bag or suitcase. USB-C compatibility means you can power it from laptop ports, phone chargers, portable batteries, or wall adapters without carrying a proprietary power brick. For race travel or multi-day trips where you might not have access to a bike shop, having the charger with you eliminates the worry of arriving with a dead shifting system.... Read More