Again, I suggest the Lenmar LIS970P. As long as you don't deeply discharge them regularly, 2 of them should get you through a typical day of festival recording 2 chan w/ +48 and meters on full during daylight gradually turning down brightness as sunlight wanes. Although I usually carry a 3rd as a safety and change 'em more often than I should to avoid discharging too deeply and extending overall battery longevity...
Have a 2nd set x3 charged for day 2 while the 1st set of 3 are charging. Lather, rinse, repeat.
FYI, I'm running a 722 recording to HDD+CF @ 24/48 and transfer from CF>card reader>PC and have *never* had the 722 fuck up where I need to transfer from HDD (other than human error). But it sure is nice to have a safety copy.
Battery life is much better when running just to CF and not powering the HDD in the 722. I'm just a paranoid freak and like having the safety track...