I bought the Motorola P513 Rapid Rate Charger from Amazon which others on this board have said works quite well. It's only $5 and Free Super Saver shipping eligible: Amazon.com: Motorola P513 Vehicle Power Adapter MicroUSB Rapid Rate Charger: Cell Phones & Service I tried it for the first time this morning during my 35 min commute to work. Started with 88% battery life and ran the GPS and slacker radio the entire drive. When I got to work, my battery had 96% power. I am very pleased so far, although my sample size is quite small (1).