Abstract: A power system including a first battery pack, a second battery pack, and a power management circuit is disclosed. The first battery pack has a first end and a second end, and has a first battery capacity. The second battery pack has a third end and a fourth end. The third end is coupled to the second end of the first battery pack and provides a low battery voltage. The fourth end is grounded, the second battery pack has a second battery capacity, and the second battery capacity is greater than the first battery capacity. The power management circuit is coupled to the second battery pack to receive the low battery voltage, and provides a component operating voltage to an electronic components based on the low battery voltage.

Abstract: A rolling sucker comprises a sucking disc, a pressing element and an adjusting rotation lid. In this case, a convex post is disposed extending from one surface of the sucking disc. The pressing element has a first surface facing the sucking disc, a second surface with a first connecting part and a first through hole going through the first surface and the second surface. The adjusting rotation lid has a second through hole. The convex post passes through the first and second through holes and has one part fixed on the adjusting rotation lid. One surface of the adjusting rotation lid facing to the pressing element has a second connecting part against the first connecting part. When rotating the adjusting rotation lid, the adjusting rotation lid pulls the convex post and the sucking disc so as to deform the sucking disc, which makes the sucking disc having an absorptive force.