Abstract: The present invention discloses an inquiry system having a database and a first testing module as well as a memory unit, a second testing module and a maximum power efficiency control unit built in a power bank. In addition to the information exchange performed by the first testing module through an external computer, the built-in second testing can perform information exchange with a device to be charged (such as a handheld electronic device) directly. Meanwhile, the charging time of the power back can be reduced through the maximum power efficiency control unit.

Abstract: A placing structure is disposed with a main body made of a flexible material and at least one sucking component. The main body is disposed with at least one through hole. Each sucking component can selectively pass through the through hole to fasten on the main body. At least one electronic device can be combined with a power bank through the sucking component, and the electrical connection is formed. Alternatively, at least one expansion module is combined with the electronic device, and the electrical connection is formed to reduce carry volume and increase practicality.