I used my GPS car charger (with USB out). Stated up to 2Amp output support. Should be plenty. It seemed to work find other than two issues: With the GPS on and audio out, it couldn't keep up the charge and the phone battery eventually died on a long drive (I've seen several people report this). The phone itself complains at times saying that the charger I am using is not an HTC certified or compatible charger and it could damage the phone Because of the phone complaining about my charger, I went ahead and bought the monoprice one. Saw several people saying it works great. It doesn't work at all. Well I should say it charges on for a few seconds, off for a few seconds, back on for a few seconds, back on. No loose connections, tried moving it to a different port, jiggled the cables, etc. Maybe I just got a bad charger. Maybe I need to buy the actual incredibly overpriced HTC charger. Ugh!