no, you do not have to use a li-ion cell if you don't want to. You can definitely use 3 AAA/AA's or better yet, 4. Just be sure to use standard alkalines if you go for 4, as the lithium style Energizer and Duracells have a starting voltage of 1.5v or more, which could exceed the `6.0v threshold for the board. Much more than 6v will burn out the board.