I run 12 sets of 12vdc LED strips for a portable craft display. Each strip pulls 2A. I power the display from two 12v deep cycle marine batteries. One battery will provide 6 hours of good light, then I switch to the other battery, and recharge both that night at home. Do you make a unit that will allow both 12v batteries to be tied in series and as the 24v. input drops, maintain a constant 12+v. output?