Hi Ian,
exactly. There are three capacitors in it with 2.7 V each (fully charged).
That's totally cool, even wth an SHV or UHV (3s / 12 V) setup, both in emergencies (total power loss) and to cushion a BEC's voltage drop (3-4 V voltage drops are unfortunately not uncommon anyway).
If you had those, an additional electrolytic capacitor would help, acting as an equalizing tank, taking up excess energy and giving it back to the circuit instantly when needed (different functionality compared to an emergency power supply like Power Backup, and both have their raison d'ĂȘtre)
Best,
Eddi
Born to fly ...
forced to work.