Improvements in and relating to battery charging

A battery charging circuit is described in which power is derived from a communications port such as a USB interface (22) and is supplied to a rechargeable battery (15) of a communications device (14). The communications device (14), which may be a mobile radio telephone, can be charged from the power supply or internal battery of a laptop computer (29) equipped with a USB port and connected thereto with a suitable cable thereby avoiding the need for a user to carry a dedicated battery charger for the radio telephone (14).