This is an 8 segment... https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTvwpptbcHLJTuY6Xw26Dlhf_zLACgBBDED2lnn8dEx7q6bh3z7cASo how can i solve this issue? I would like to use 7.4v batteries
Since the 7.4 volt pack could cause problems with the regulator dropping out and not providing the full 5.0 volts, you should go with the 11.1 volt pack, but you run into the problem of heat on the boards regulator.
BTW i really dont get the point of making arduinos not supporting higher voltages. 5v is too much for standard batteryes too low for li-po packs. I have a project with a myAVR board that i have purchased year ago, and this is working with different voltages, from 7v to 12v , you should just set the battery on the menu. And there is no heating, no regulator theory etc.