When do you quit flying?
That is the kind of info I want! If it doesn't start warning till 8.5, wouldn't it make sense that it is still safe to fly? I'm not positive, but I don't think RF output is related to voltage until it gets real low like 8.5. I may be wrong but the RF output is modulated(terminology???) irrespective of voltage until it is too low to safely control the model hence the warning buzzer at 8.5volts. I probably should have put this in the Futaba forum to get a direct answer from GP/Futaba.
basmntdweller