I'm going to be taking a long trip this week on my car, and unfortunately my cigarette lighter is busted, so I can't use my AC/DC converter to recharge my iPhone. Is there an alternative power source I could use? Some kind of portable plug-in battery or something I could get? My only alternative is to pull off the road somewhere when my iPhone battery is almost drained and hope to find an outlet in a store and plug in while I sit and wait on it.