Another thread for the C3k Zaurus talk about using USB charging/sync cables. http://www.oesf.org/forums/index.php?showtopic=13362&st=15
I wonder if it works for the Z5500? I've seen eBayers seller such cables, including travel kits with AC/DC and car adapters with USB female connectors that provide 1A current.
The power specs for Z5500 is 6.2w@5v, ie 6.2/5 = 1.24A while the SHARP AC adapter is rated at 5v@2A. So question is, are those kits sold on ebay underpowered?