These spy-flyers could get a much longer range with the second battery bank and an energy recovery circuit.
2 full batteries, double range.
Battery A goes dead (not flat, just discharged to mfg’s specs)
B kicks in with a relay
ERC charges A while B flies the critter
B runs down, A kicks in
ERC charges B while A flies the drone
and so on, until the charge system senses a lower charging level, and signals the pilot to return to base.
"ROGUE ELECTRICIAN" Hoping to be around to re-energize the New World.....
Cogito, ergo armatus sum