Using a 1 amp charger, you can expect an empty 10,000mAh power bank to be fully charged after 12–15 hours. It depends upon the charger you are using. So yours is a 10000mAh power bank which is 10Ah. Lets say your charger is rated for 1A then it would take 10 hours (1*10 = 10AH) for full charge.