LiIons have a funky charge cycle. They go up from near empty to showing almost full capacity very quickly, but most of that is "ghost" capacity; if you don't let the charge cycle complete itself, you'll end up with what you might think is a defective battery. This is another reason why it's good to "top off" LiIons: You get less of the ghosting effect if you unplug them too soon.

So, if possible let the charge cycle complete itself (for the Itablets that means: Wait until the battery icon shows full capacity), especially in case of a deep discharge.