[EricH]

I think, if that's all you're doing, then you may need to do some further consideration.

1) Will this display be attended? I know you said it will be roped off. However, for safety, I would never, ever leave a live robot unattended, no matter how up on blocks/behind ropes it was. Also, for outreach purposes, maybe having someone there to say when and where meetings are would be a good idea. (If this is at a school, though, that person might have to be a teacher or administrator.)

2) If you're just doing that much with the robot, I think having someone walk by during a passing period to check on the battery voltage should be quite sufficient. The main thing I'd be worried about is compressor draw when it's charging the system; check for leaks before the event or hook some extra tanks into the system so it doesn't have to work as hard and you shouldn't need to be worried about that either.

To be honest, for one motor and the compressor, running every 5 minutes, you do not need a charger connected to the robot. You can have someone who goes by the robot do a quick battery change, and put the old battery on a charger. That should keep you running all day without being concerned about whether or not the voltage from a battery/charger system will fry the PD board.