It takes approximately 4 hours to charge the StainZero. If you notice that it is taking much longer than 4 hours to charge, or if it isn’t charging at all, then check that the charging cable is fully inserted into the vacuum’s charging port. Clean both the cable and the vacuum’s charging port with a soft, dry cloth, and make sure that no dirt, dust, or debris is stuck within the charging port. You should also do a scan of the AC outlet that you are attempting to use for charging the vacuum. It should be dry, clean, and located far away from any heat sources, water, or any other liquid, as well as children or pets, since they can damage the outlet. The AC outlet should also be in a relatively cool, dry environment. If the outlet is wet, visibly damaged, malfunctioning, or located in a hot or cold space, choose a different outlet. Never attempt to charge the StainZero if its charging port is wet, leaking, or visibly deformed or malfunctioning in any way. Immediately contact us for further information.