I have put together a small embedded Linux box to use in my truck. The last detail is power. I would LIKE to run off of a rechargeable batttery when there is no power (ie the truck is off or the unit is out of the truck),when there IS dc power then run off of the external power AND charge the batteries. To date the entire project has been "off the shelf" I have only assembeled and configured. So if possible I would like to continue this philosophy and use an off the shelf unit.