Juan C G.wrote a review of Shimano Di2 Internal Battery Charger on September 7, 2016
Familiarity: I've put it through the wringer
All you need to charge your di2 E-tube Cockpit junction box. It also works great to keep your di2 system up to date with the lastest firmware. Just plug it to you bike and your pc, download the lasted Shimano software and follow instructions.