Youshould not leave your power bank charging longer than necessary. Your manufacturer's instructions should let you know roughly how long it will take to charge. Most power banks charge within 1-2 hours. 4years ago. Updated. The time it takes to recharge your power bank is dependent on a number of factors such as the size of your power bank battery (mAh) and the wall charger you're using. Below is our table that shows approximate charge times for each sized power bank for the different type of wall charger you're using. Thenumber of times that the power bank can be used for charging depends on its remaining power supply, the battery capacity of the charged device, the quality of the charging cable, and the charging environment. When the power bank is fully charged, the number of charging times is equal to the result of (5 V x Rated capacity of the power bank X4V2.