AIR BOSS said:
On pg 24 it will tell you about the batteries. If people would just read the manual, they would find the information they need to avoid the problems they are having.
Gee that's helpful...
The manual does describe the remote's battery indication functions but I believe the question was more about technique from experienced users, which is a good question and deserves a "proper" reply. What the manual does not state and I believe is the heart of the question is how fast does the controller go from the initial battery low warning to the critical battery low warning which will force the controller to shut off after 3 seconds. And do you have the time to return after you receive the first warning before the second occurs.
Since others have mentioned the draw rate, and their personal experiences... I will only say I have not changed mine in 50 flights and am sure they may be close to being needed to be replaced. I will probably wait until I get the alarm as I do not regularly fly great distances away. But I too agree there is something to be said for peace of mind.