Recently returning from a trip to Mongolia, Nevada Wier recounts her frustrating experience with portable hard drives (aka digital wallets). It appears she purchased two of these gadgets before her trip and while in the field, these hard drives would not hold a charge, and eventually would not work.
Nevada suspects the battery issue was caused either because the only available electricity in Mongolia was 220AC or through generators. In the meantime and until this is resolved, she's withholding her endorsement of this hard drive model.
I think the lesson we all learn from this experience is (1) hard drives will fail when you least expect it, or where you have little chance of having them fixed quickly (this is also known as Murphy's Law); (2) to never take a newly acquired gadget, camera, accessory on a trip without having it been tested (although in this case, it seems that the drives worked well in a 110AC environment), and (3) always have a back-up solution.