Educate me on 12 volt batteries

Basically 6V deep cycle batteries are constructed for more AH and longer service and hence more suited for off grid use. For pedestal to pedestal or light use camping 12V starting batteries are adequate.

For starters a 12V starting battery has about 80Ah+ (160Ah for 2) while 2x 6V have 220Ah.

12V marine deep cycle batteries are a compromised starting battery and deep cycle in name only.