Not sure, but I think you should try those high capacity (and rechargeable) AA battery which are NiMH or the recent Lithium Ion batteries which are rechargeable.
Choking on the stench of ambition in Washington DC
Status:
Having seen wifi drains on my CE 2.0 AA-driven devices, I would say an external battery--if you're on-line for anything longer than an email check--might be a requirement.