What is the best way to keep track of the remaining battery voltage while in fly? I know one can check the voltage from the transmitter but I found myself distracted during fly and forgot to check the remaining juice. Lucky so far... I have landed close to 3.2, but I could see myself forgetting to check the voltage while flying and photographing an interesting subject. Can you set an alarm in the transmitter? Wondering how others do it. Thanks for any advice.