I have a bunch of relatively inexpensive battery-powered radio-controlled aircraft that I haven't flown in over a year. I haven't flown some of them in over 3 years.
The aircraft are airplanes, helicopters, and drones.
I believe they are all powered by LiPo batteries that are designed to be recharged, not replaced.
From what I've learned about LiPo batteries, they tend to go bad if not used for a long duration.
What general steps do I take to resurrect all these aircraft so I can fly them again?