One car battery charger 

Canon CBC-NB2

The CBC-NB2 powers the camera or charges the battery by plugging into a car's cigarette lighter socket. This adapter will charge either NB-2L or BP-2F12 batteries. OPTURA 40, OPTURA 30, Elura 40MC, Elura 50, Elura 70, Elura 65, Elura 60, S45, S40, S30

The Canon CBC-NB2 Car Battery Charger lets the camera draw power via a car's cigarette lighter so that you can use it on the road. It is compatible with Canon PowerShot S50/S45 digital cameras.