Nowadays, most people are using smart phones and using power banks as backup power sources. However, most of the power banks on the market are heavy and inconvenient to carry. When traveling far away, power is not easy to obtain. When power is needed temporarily, a mobile power bank can come in handy. The motivation for making the hardware in this article is that when the mobile phone is out of power and needs power temporarily, it can be charged immediately. The hardware uses AA batteries to achieve the charging effect through a boost circuit. You can also bring your own rechargeable battery as a charging battery. If the battery runs out, just go to a convenience store to buy batteries and you can continue to charge your phone. Although the charging speed is not fast, it can reach the minimum maintenance power required for temporary emergency calls.