debian? fast discharging due to wallcharger?

[arne anka]

i noticed the issue occasionally, but never that extreme:
sunday night (at about midnight) the battery was at about 53%, thus i  
plugged in the wallcharger.
at about 8:30 the led was blue and the battery at about 83%, re-plugged  
the charger. when i left home it was at 99%, discharging. i disconnected  
and  supended and did not touch it until 24h later -- and the battery was  
flat!

so. my impression is: charging with the wallcharger may charge faster, but  
discharges very fast, too!

does someone else experience this?