The only time I use the batteries to my e-cigs is when I am outside, away from home where there's no power outlets available. At home, I use the dual power USB outlet plugged into the wall socket.
If I travel in the car with my MIL, oldest daughter, or DH, I always have a little but powerful power inverter that plugs into the cigarette charger of the car. My MIL's car has three cigarette charger slots, one for an actual cigarette lighter an two more just for plugging in for power items like the inverter or cigarette lighter plugs for power access.
Both these methods work well to charge the Dura-C/510 manual and the Janty Stick batteries.