If one battery voltage drops or goes dead, it will sense and automatically switch and supply from the remaining pack supply to both outputs as a backup.
Switching to a backup is the easy part. Achieving a balanced system that will let you draw down both packs evenly is the part that Tech-Aero excels at. Both halves of the system are always in operation. Why carry extra battery weight around that is only useful if half the system fails? And how sure are you that it's operational if the only time you exercise it is during that unexpected in flight failure. Not for me! Instead, you want to carry an always functional redundant failsafe system that provides safety, reduces weight, and also provides more peak demand current than a single 3A regulator system can. Also, the regulators are easily programmable to any of 32 different voltage steps.