After discharging the entire battery, did a full wall-socket charge during 5 hours.
Before going to bed, I put the settings in 15 sleep, never power-off (as the defaults), also I used the KT for at least an hour.
This morning, battery was at 100%. No drain at all.
What's it's going on here??? Well, let see what happens this evening.
The only different factor it's that I used another charger, actually my HTC phone charger. Previous charges were made with and Apple USB wall charger for iPods, phones... and I suppose that they both work as it should.