the question is... why?
I assume you are talking about this one:
BG 9-12-130 Super X-Treme Run Time Portable DVD Player Battery
9V/12V DVD Battery Pack. Most popular for the use with 9V and 12V portable DVD players. 130Wh Capacity = up to 14+ Hours of continious movie time per charge, 9V~12V output. 9V/12V selector switch. Tolerance up to 4.5A.
at 9v output setting, 130Wh = 14.4amp-hours. I think the V3 pulls around 1 amp max (although I might be off, that's just what I recall), so yeah, in theory that would get you just over 14 hours of runtime. but it's $200
alternatively, you could get a 6v, 12amp-hour SLA battery for about $15.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2088solder on a wire and a 4-pin XLR (another few of bucks), and your're good to go for 12 hours (in theory, anyway. in practice, you never want to totally run SLA batteries down, because it's not good for the battery). and the total cost, including connectors and whatnot, probably under $25.
sure, the L-ion battery is smaller and lighter, but in my mind, it doesn't make up for the huge extra cost