Traveling to places where mains power is not available? No Problem! You can charge your Pilot-24 CPAP Battery from your vehicle's 12V cigarette lighter adaptor! Easy to use: plug one end of the Medistrom™ Car Charger into the car cigarette lighter socket, and the other end into the 24V transformer. Use the S9 Output Cable that is included with your Pilot-24 to connect the car charger to Pilot-24 CPAP Battery. Insert one end of S9 Cable into the 24V transformer, and another end into "CHARGE" jack of your Pilot-24. The CPAP battery will fully charge in 3-4 hours.