I found these two phones from watching a few random videos a while ago, both have monster batteries.
I think BLU also makes a phone with like a 10,000 mAh battery phone but I'm not 100% sure.
BLU Studio Energy 2
http://www.amazon.com/gp/product/B01686OYK6?ie=UTF8&camp=213733&creative=393177&creativeASIN=B01686OYK6&linkCode=shr&tag=ytube006-20&linkId=QTPRFN2U3YKZZVVP&qid=1448047593&sr=8-3&keywords=blu+studio+energy+2
BLU ENERGY X
http://www.amazon.com/gp/product/B015XIHS62?ie=UTF8&camp=213733&creative=393177&creativeASIN=B015XIHS62&linkCode=shr&tag=ytube006-20&linkId=3IHBJG635M5TSVPY&=wireless&qid=1448047527&sr=1-4&keywords=blu