We have two children and are going on a very long trip (plane) in the summer. Desperate to bring along portable DVD players which last for as long as possible but all the ones I have seen with rechargeable batteries only last 2.5 hours. What do people do? Can you buy extra batteries for them or is there one which has a really long battery life? Thanks for any advice/thoughts. No access to power on the plane unfortunately and no kids TV for 12 hours or so... [sceptical]