Terminal 2 charging

AlvinB

The handbook says that terminal 2 on the 12S plug has not been used since Sept 1998, and sure enough my April 1998 caravan does not have it connected (though it is not connected to earth as the handbook warns it may be). Does this mean no post-1998 caravan
can charge the battery while towing? And if not why not? My new towbar has ignition controlled supplies to pins 2 & 6. Can I just connect my caravan battery to pin2 +ve and pin3 -ve or do I need to fit a regulator? Any ideas welcome.