The Bright Max and Bright Max Plus come with a Micro-USB cable for charging.  This cable needs to be plugged into a charging block that is 5V with a minimum of 2A (2,000 mA).  Some charging blocks that come with phones may not be enough.  A 1A power block will underpower your speaker, causing the battery to have a short life or not power the speaker on at all.  If your Bright Max or Bright Max Plus is having battery issues, try replacing the block with the correct specifications and charge the battery overnight.