I was referring to the "Memory saver" part of the site. It's supply 12volts through the cigerette lighter before connecting the car battery. Some of these memory savers have a surge protector build into them. My thought would be:
Before connecting the car battery you plug the memory saver into the ciferette lighter socket (with the surge protector built in) after you have the system charged to 12 volts then you attach the battery cables. Should be no, or little potential difference so there should be no arc and no spike.