Hey Jeneralist, I suppose the first question you will want to answer is if you will be near civilization or not. In 2010 I rode from KCMO to Marietta, GA. Two weeks, 1006 mi. I rode in and out of some very remote areas for a few days at a time and then back to civilization. I brought my phone and a 110 wall charger. I never had any problems finding power. On tours I bring a little socket test light ($1.00) and my wall charger. In the US, most Coke machines, ice machines, many parks, and a whole host of eating places, coffee shops, gas stations (open or not) will have power. I'd plug in and take a short break or drink a cup of coffee while my phone charged. I asked, if there was someone around.
Jharte