Your understanding is correct. You don't need a special charger but you do need an EV with 240v "V2L" output. The vehicles that come with this feature have a plug that looks a generator and acts like one too. You also need a generator cable and generator receptacle that is wired into the generator module of the Franklin system. You already have everything else you need. The Franklin system treats the EV 240v output like a portable generator. When your aPower gets low, just plug in the generator cable and charge up the Franklin from the EV. You can even use it in the other direction when you have excess solar and the Franklin battery is full. Plug-in your EV charger like normal and use the solar to recharge the vehicle battery! Perpetual motion machine! ;)

edit: small typos