Charging base

A charging base, disposed on a bearing surface and configured to charge a mobile device, wherein the mobile device comprises a bottom base, a contact portion disposed on the bottom base, and a drive wheel protruding from the bottom base and driving the mobile device to move, and the charging base comprises:

• a charging cradle, comprising a platform and a charging contact portion, wherein the charging contact portion protrudes from the platform, and a first height existing between the charging contact portion and the bearing surface is greater than a bottom base height between the bottom base and the bearing surface;
• a pad plate, disposed on a movement path on which the mobile device moves toward the charging cradle, wherein a second height exists between the pad plate and the bearing surface, so that when the drive wheel moves onto the pad plate, a sum of the second height and the bottom base height is greater than the first height;
• the bottom base of the mobile device is located above the charging contact portion, and a first gap exists between the bottom base and the charging contact portion;
• and
• a recess positioning portion, disposed between the charging cradle and the pad plate and located on the movement path on which the mobile device moves toward the charging cradle, wherein a third height exists between the recess positioning portion and the bearing surface, when the drive wheel reaches the recess positioning portion while moving from the pad plate toward the charging cradle, a sum of the third height and the bottom base height is less than or equal to the first height, so that the bottom base covers the platform and the contact portion is in contact with the charging contact portion.