Some people have problems charging their iPod. There are some manuals explaining how to charge your iPod easily.
Charge it With Computer/Adapter
1.Connect the USB cord to the computer or adapter’s USB port. Some adapters will require no assembly and therefore will have no USB port (often those for wall or car outlets).
2.Connect the other end to the iPod. For most ipod connectors just push in gently, but for other types you will have to press firmly on side buttons to pull in side prongs.
Charge it With Stereo or Dock
1.Make sure the stereo is plugged in.
2.Place the plastic insert (if applicable) that came with the stereo or dock over the port. This is only needed if you have an iPod smaller than the iPod classic. Also, an iPod with a thick cover or skin may not fit properly.
3.Connect the iPod to the dock or stereo.
Charge it With Power Bank
Also, if you charge your iPod on a regular plug, turn it off, it will charge faster.