This is just my experiance, so if someone knows better please correct me.
But, the software indicator uses quite large steps. Hence it may show full even when partly drained until it gets to the point where it updates to 75%. Better option is to wait for the light to go out.
Having said that, I have actually found that sometimes the light does not go out at all (gets confused ?). Never had a problem with the battery as a result though.
Not sure how the Zaurus charges. Perhaps it does the final stages as a trickle charge as it were which migh explain the long time. Also keep in mind that it is quite a large battery most devices only have half that and so the extra charge time may simply be normal.
As some point, when I have an almost flat battery I\'ll time it and see when the light goes out.
Another simple test, after you have done a full charge (light out), unplug and replug the charger. Should find that the light goes out much quicker indicating it is working as expected.
All a bit fuzzy, but that just reflects my understanding of it I\'m afraid.