I have a 12V Cessna with the external power receptacle just forward of the pilot's side door. I recently bought one of those little jump packs for emergency use. Do I need to buy one of these as well? https://www.aircraftspruce.com/catalog/elpages/plugnjump.php I have always assumed that the answer is yes, but I find myself wondering if I really need a nearly $100 interface to go between the plugs and the... other plugs. If I can reach with my alligator clips, can I just go directly to the external power receptacle? If not, is there a less expensive version? (the "cessna" version, amazingly, costs less - $37.50 - but won't take alligator clips).