You can easily check if the lighter socket is permanently live, or switched via the ignition. Plug something into it (e.g. phone charger, sat nav) and turn the ignition on and off.
If live when ignition off (and it should be), you can charge through it. My 4/4 is almost permanently left connected to my CTEK 3600 smart charger.
The only issue for me was that Morgan had not connected up the lighter socket! Easily solved once I found the purple cable amongst the rats nest of wires laughingly called a "harness" apparently randomly crammed up behind the dash. But the supplied socket is very cheap and nasty, and doesn't make a good contact, so I swapped it for a marine grade socket (Sutars) - much better.
Nigel
