I have seen the same think - most likely backup battery is gone and should be replaced. My problem was caused by an application which wakes up J728 during midnight and put it in active status
(green light flashing
). I do not know why but power setting which are supposed to shut down device in 2 minutes does not do so. Thus main battery drains for several hours and after that backup battery is heavily used. I replaced 2-3 backup batteries until I found what is wrong. Right now it is the same story but I found that device is woken up ones a week Wed/Thu midnight. So every Thu morning I shut down J728 manually
Unfortunately I do not know how to see which application causes this problem. I do think it is some of Alpaxo applications
(3ComĀ® Wireless Drivers or WLAN Monitor Utility - good applications at all
) - I bought Wi-Fi card from them. There is no such a problem on cleared J728.