[dangerdoc]

I prefer the Samsung because of some of the work I do. I have a travel memory card with all of my reference material pre loaded as well as a couple of spare batteries. Sometimes I go nearly a week between opportunities to recharge. 

[Bubba_Leroy]

I use a Jackery external backup battery. It can fully recharge my HTC Thunderbolt up to three times before I need to recharge it. I keep it charged using a USB port on my PC when I am in the office and grab it when I am going to be on the road.

They sell larger models with much longer charges, but this one is about the size of a cigarette lighter and only costs $30.