The 2000 Mah 6v five cell packs are my go to batteries for the majority of my fleet. If you really expect to get the promised capacity of that pack then its time you get a real charger, a simple basic four button smart charger that you can vary the charge current.

Using a wall charger intended for 4.8v 500 to 700 mah packs is a very poor idea since virtually everyone gets confused on the time and I get students all the time doing just this complaining about bad packs. Even last year witnessed a fellow loose his airplane due to a 6v 2000mah that had never been properly charged with wall worts. Your packs best overnight charge rate is 200mah.

John