The cigarette lighter socket re-purposed as a DC outlet is a disaster despite being adopted as an industry standard. The sprung centre pin and insecure locking of outer regularly cause intermittent connections.
Add to this minimal wiring dimensions, a 10 amp limit (if you are lucky) and strong likelihood you won't get full benefits of charger due to volt drop on the tenuous connection.
I would never use one by choice fitting instead the compact Hella/DIN type allowing captive plug and higher current rating.
Better still connect charger directly to battery or engineer dedicated charge cable as Keith suggests.
Note a battery within its working life should be fine to start a any car even in winter, if it's not left for more than three weeks between full charges.
