Thanks for your enquiry.
Generally the battery will last for about 2 hours. You can set the player to power- saving mode to keep the playing time longer.
You can also set the power save function to make the playing time longer in this way: System setup----LCD-----Black-----5/10
And the manual is for all the mp4/mp3 we have. There will be differences with some of models.
Any other questions please feel free to contact us on https://help.tinydeal.com/contact-us.
And we would answer you within 24 hours.
Have a nice day!