Nobody goes Di2 so that they can mount an unsightly battery somewhere on their gorgeous bike. Shimano knows what is up and the internal battery was a quick answer to the complaints of the original external battery. The only needed component is one of the cockpit junction boxes to attach a charger, since the battery is no longer easily removable for charging. Either the 3 port SM-EW90-A or the 5 port SM-EW90-F will do the trick. A full charge will last well over 1,000 miles in the worst cold weather conditions so charging once a week is more than enough to keep you topped off for any ride. The 7.4 volt lithium-ion battery has no charge memory, so just like your phone, you can leave it on the charger without worry of degrading the battery. Shimano's junction box displays battery power at any time with the push of any button on the system. A light indicates green for fully charged, flashing green for 50%, solid red for 25%, and a flashing red indicates it is critically low.