All the actors are assembled and your batteries are dead but you can pe prepared for this sort of embarrassment with the Dracast NP-F 6600mAh 2 Batteries with Chargers and V-Mount to NPF Converter Kit
The kit includes two 6600mAh lithium-ion batteries, two battery chargers, and a V-mount to dual NP-F converter. The kit provides power for LED light fixtures for approximately 270 minutes, while the converter lets you power V-mount equipment using the NP-F batteries.
The Dracast 2 x NP-F 6600mAh Batteries and 2 x Charger Kit provides power to LED light fixtures when mains power is unavailable. The kit contains two NP-F 6600mAh lithium-ion batteries and two multi-voltage chargers. Runtime is approximately 270 minutes with Dracast's LED160, LED200, X1, or X2 lights on a fully charged battery.
This Dual NP-F to V-Mount Converter Plate from Dracast allows you to power any V-mount light, monitor, or other piece of equipment with two Sony L-series/NP-F type batteries, as long as the voltage is equivalent. The combined voltage of the two NP-F batteries will be 14.8V, which is the standard output power of a V-mount battery.