In the event that you are only using four ports on a Pro 800, you can conserve battery life by turning off the unused Reader. This can easily be done through BoxScore.
From the main screen, press Configure > Power and press the button for the Reader you wish to turn off.
Remember that Reader 1 = Ports 1-4 and Reader 2 = Ports 5-8
Warning: If for any reason during your race you need to turn a reader back on to connect antennas, remember that a Reader can take up to 5 minutes to completely boot. Please plan accordingly.