Unlike the li-ion and li-polymer, the only way to know if the niquel based batteries are charged is the temperature, it increases when they are ready. Usually cheap chargers measure the charge with time, they mention 8 hours charge because its the theorical time needed to charge the batteries at about 1/10 capacity of the battery.
If the charger uses 200mah then it will take 10 hours to charge a 2000mah battery
, bigger currents will affect battery life.
Anyway who cares, batteries are so cheap...