WARNING: 

MUST use USB Charger with output 5V 1A (e.g. iPod/iPhone 5V1A charger). 

MUST NOT use computer USB port (5V 500mA) which might under charge the product. MUST NOT use 5V USB Charger with output current larger than 1A, Quick Charge (QC) / Fast Charge / Large Current Charge / iPad Charger / Digital Camera Charger because it might damage the product, shorten battery life and playtime which will not be covered by warranty.

WARNING: Don’t leave the product connected to charger overnight.