6 volt vs. 12 volt batteries

Thanks for the helpful information. I do believe that most battery banks ARE woefully undersized. In the past (2-12 volt batteries) I would charge the batteries all day for a full charge. Just running the heater overnight (in cold weather) would completely drain both batteries. I was hoping that 2-6 volt batteries would prolong the battery life so it could at least have enough juice to start the generator in the morning! :) As a backup I will be bringing my Honda.

I have considered adding two more batteries for a 4 bank system.