It's going to be used inside a commercial vehicle and it has to supply power to the cameras.  I'm mistaken, it just has to have 12v in and no batteries. 
  
quote="securitymonster"]Thats going to be a tough one. Most mobile devices that are battery operated are single channel recorders, and your lucky to get 8 hours of operation on a single charge of batteries. 
  
Whats your application? Maybe we can point you in the right direction if we can further understand your project.