We have spend much time testing the recording in order to find the best compromise between precision and battery drain. However, the battery consumption is still higher than with normal use of the app (without GPS), because during recording the smartphone constantly queries the location via GPS signal.
There are several possibilities to save battery power:
1) iOS: You can reduce the precision of GPS.
2) You can darken the screen.
3) You can close other apps which are open at the same time.
4) Shooting photos consumes much battery. Therefore, you need a lot of battery to make photos during the tour.
5) With Pro you can save your map/tour offline before the recording and deactive the mobile data connection. In this case, unnecessary data will not be reloaded and therefore less battery will be used.