I need to replace my batteries (group 27) which now are wired as bank one and bank two through a three postion switch. I would like to create a system which keeps the two group 27 batteries for house use and add a dedicated starting battery. I'm not sure on how to wire the starting battery into the system. Can I simply connect the two group 27's as bank one and setup the new starting battery as bank two? If so, how does the starting battery get charged? I now charge with the switch on both. Is this ok with these different kind of batteries? Any feedback will be greatly appreciated.