The standard of computer USB power supply is 5v, and the protocol stipulates 500mA. Generally, electrical appliances powered by computer USB can be powered by batteries, but the battery capacity is small, so the use time is short. The electric mouse pad has never been used, and it has never been integrated into the insole of height-increasing shoes. I don't know exactly what the current is, but 4-5v is definitely more than 100-200mA and less than1w. Why? It is estimated that it needs at least 4-5w, that is, the current of1a. It is very simple to integrate the electric heating pad into the insole of high-top shoes. Technically, it's not a precise secret thing, so there should be no obstacles. Like the mobile phone board, it is a lithium battery with an inherent voltage of 3.7v instead of 5-5.5v and a capacity of more than 2000mah. Charging with mobile power supply is feasible in theory.