What I just found in a quick check is that there already are battery packs that can be used...
Also some discussions below the video: http://www.youtube.com/watch?v=jsxktBqKBu8
And according to this discussion, any inverter pure sinewave battery pack should be able to work:
Interesting discussion by folks who already tried battery packs with the Dlite 4s: http://photography-on-the.net/forum/...pack+for+Dlite
More discussions: http://photography-on-the.net/forum/...pack+for+Dlite
This was also mentioned in other discussions: http://www.innovatronix.com/detailpa...&categoryid=42
And someone who DIYed a battery 'pack' for his Dlite: http://photography-on-the.net/forum/...d.php?t=689719