The Party Splash Link comes with a USB-C to USB-A cable for charging. This cable needs to be plugged into a charging block with an output that is exactly 5V with a minimum of 2A (or 2,000 mA). This will be printed on the charging block.
Some charging blocks that come with phones may not be enough. A 1A (or 1,000 mA) power block will underpower your speaker, causing the battery to have a short life or prevent the speaker from powering on. If your Party Splash Link is having battery issues, try replacing the block with the correct specifications and charge the battery overnight.