CTEK Cig-Plug (Part No. 56-263) enables charging the battery through the cigarette outlet (if outlet is live with ignition switch off)
It eliminates any hassle, simply charge from within the car, suits perfect for CTEK's battery charger with Comfort Connect, UC 800, US 800, MULTI US 3300, MULTI US 7002, US 0.8, and MUS 4.3.
Note that the vehicle
needs to have power on the cigarette outlet when not in use.