Disclosed is a method (200) for charging energy storage devices. The method (200) can include a battery charging method in a power supply client connected by a data bus to a power supply host. The method (200) includes the steps of: detecting (210) a state of the power supply host; determining (220) a limit of current from the host to the client; allocating (230) a portion of the limit to a battery charging current; and charging (240) a battery of the client at the battery charging current such that the current from the host is greater than a recommended limit and less than or equal to the determined amount. Thus a client device can confidently charge at a rate which causes the port current to exceed a recommended limit, such as a USB port limit of 500 mA, when allowed by conditions of the host device. Advantageously, the method can help to expedite the charging time of a client battery, notwithstanding the number of other clients connected to the same host device for charging, thus minimizing the wait time of a user.