Ken is correct. But, I believe the voltage is lower than that. What happens is that the receiver will cycle and will "reboot" once that voltage is reached. If your receiver battery is that low, then you should not be flying it.

I have had the Spektrum DX7 for over a year and a half now. I have never... never had a reboot situation.

One way to prevent that is to use 6 volt receiver battery packs. That will insure that you never see that low battery voltage and cause a reboot.

From what I understand, they have modified the operating system so that reboots take less time, in the order of less than a second. So if it ever did happen, you would probably never realize it. But if it did happen, then you should reconsider your style and charge more often... or switch over to 6 volt packs.

CGr.