Rendr wrote:Yeah that would look slick. Another thing I was lookin into was somehow attaching some kind of battery casing on the side to fit aa's. That would then go to a small inverter which would then bypass the internal tranformer so the batteries don't get drained hella quick. I'd need to throw maybe a switch from ac to dc in there somewhere i reckon and a fuse incase i forget to switch to the tranformer after usin it on batteries. A bit of research to be done, but ima check it out. Anyone know about this sort of stuff hit me me some suggestions!(and no i aint gettin a 500, it aint the same 
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I think your final assesment that the 500 is not the same is correct...
The 500 doesn't have a mains transformer inside. Instead it has a low voltage DC input and a external transformer (like on a laptop computer).
I don't understand why you want to include an inverter. This converts DC to AC. You would then use the internal power supply to convert this AC back to DC; you would waste a lot of power doing this.
What you want to do is work out what DC voltage the internal PSU generates and put your switch here. When the switch is switched, you apply the voltage from the batteries via a diode. When it is unswitched you disconnect the battery. In both switch positions, the PSU output is always connected.
that would be the way I would do it. Best cells to use in your battery are lithium. Lithium ion are good, lithium polymer are lighter, higher capacity but more expensive.
It is worth having a facility to monitor the charge level too!
It should be reasonably easy to implement, providing you don't tinker around in the PSU section itself. (I.E. lethal voltages and nasty things like that)
I'm afraid I don't have the time (nor inclination tbh) to help on a project like this, but good luck.
