Hold down one of the left/front shifter buttons until the red, green or both lights illuminate.
- Solid Green = 76% to 100% battery charge
- Flashing Green = 51% to 75% battery charge
- Solid Red = 26% to 50% battery charge
- Flashing Red = 1% to 25% battery charge
The lights will then change to indicate the shifting mode:
- Solid red+green lights indicate manual shift mode
- Two blinks indicate Semi-Synchro Shift mode
- Three blinks indicate Full-Synchro Shift mode
This isn't everything Di2 can do but it is a start. Checking the battery is the number one thing you need to do so it will get you started.
-Tim-