Hi Jason. 7.5 is correct. I never run my 500/750 with less than 7.8 on the ECU Pack. I usually quick charge the pack between each flight. The pack is a 7.2 volt pack but you can get well over 8.0 in them. If you do end up quick charging the pack before each flight (which is what I would recommend) make sure you do a deep cycle of the pack every so often. Quick charging often lessens the capacity of the pack hence requiring a deep cycle to get the capacity back up. Good luck!

Spencer Maze
RAM Enthusiast