I chose the following storage device for my African Safari last June. I investigated with due diligence all the choices on this Adorama site. Read all the reviews pro & con, filtered out the BS. During the 2+ wks bouncing around with me in a Landrover, the 2730 performed without any burps. Prior to my bucket list Safari, I used the 2730 on a daily basis for confidence in its survival and how to use it--at the end of long day how-to should be second nature. The mini display screen images reaffirmed its proper function. Not inexpensive, but dependable--too many review comments for other devices had 2many negative vibes!! The 2730 is an excellent standalone 500G HD for temp backups or storage when living with your PC at home. I forgot--fits into your jacket pocket, very convenient.
This is the 2730, with 500G, there is a 750G model. http://www.adorama.com/ND2730EPS500.html
This is the pdf manual: http://www.internationalsupplies.com/images/stories/brochures/NEXTO-ND2730.pdf
Check out this replacement or backup battery for the 2730. I think it can have its output connected to the DC input of the 2730. http://www.adorama.com/NDIBF2730.html
I have dealt with Adorama for ~2 decades, no hassles and free shpg!!!
enjoy irv weiner