The time required to fully complete a charge cycle varies with a couple of factors, including the power output of the battery charger and the capacity, age or condition of the battery pack. General speaking, follow the C/5 rule to ｓｅｌｅｃｔ the best fit charger for the battery pack, i.e., Capacity (of the battery pack in ampere hour) divided by 5 would give you the charger of desirable charging performance while offering the best protection to the battery pack.