I don't think I've ever heard of the batteries actually charging an ipod to full charge before. The 8 AA's might give you a better battery life, but you would have to factor in cost vs. the 9v batteries. If you don't let your battery run down all the way, using the emergency charger always, I know the 9 v will give you a 8 hours of additional playback. I think the AA's will give you a moderately better charge, maybe 10 hours. If your battery is run all the way down though, more power has to go to charging the battery, so you might get 4 hours out of the battery. Personally, I would go with the 9 v for your usage. They're much lighter since it sounds like you'll be living out of your pack, and so you can carry more of them. Like I said, just don't let the battery get down below about half, or else the batteries won't do much. Plus, the 9v accessory is much cheaper to buy, about $15.00 I believe. Hope that helps. Let me know if you need any more help.
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