Battery LifeOne of the main questions about moving to electronic shifting is battery life. You definitely don't want to be worrying about whether you have enough battery to get you home. Shimano claim excellent life from the Di2 battery. My findings definitely confirm that. Where I normally ride, which requires regular shifts as gradients change frequently, I estimate that 10% of the battery lasts in the region of 150 kilometers. I typically top up the battery no more than once a week.
Recharging the battery for Di2 is also fast. You'll need a mains adapter that can charge devices that use a micro USB port. I use the one for my mobile phone. Di2 uses a small interface box that has a micro USB socket on one end and a cable to the special connector for the bike on the other. The connector socket, which is protected by a waterproof cover, is on the control unit, which sits below the handlebar stem.
The interface can be used to charge the battery, or to connect a PC, of which more later. A light on the interface glows while the battery is charging, and goes out once it's finished. The interface seems to remain cool throughout the charging process.
The control unit on the bike also has a couple of lights on it. One of these provides a quick check of battery status. If the front mech is in the small ring, pressing the down shift lever for a couple of seconds will provide battery status. If the light glows green, you're good to go.
Configuring Di2With PC software that can be downloaded from the Web, it's possible to configure various aspects of Di2. For example, I swapped the function of the shift levers so that the larger one on the right bar moves to a smaller sprocket on the rear. This is to match another bike I have with a Shimano rear mech that has reverse springing.
This software also allows updates to be applied to the firmware in the Di2 components on the bike.