I have the same charger you have. I charge my 600 Mah batteries at 1 amp at the field. Takes about 30 minutes when the battery is not fully discharged. I usually recharge after about 4 flights. The charger will beep loudly when the battery is charged. It will then switch to a trickle charge and the light will continue to flash until you remove the battery or push the button again to stop the charging. I do this only for "quick" charging at the field. I always charge overnight with the wall wart before I go flying.