Bolt VD-420 Wireless Manual Flash - Manual (Page 15)

Automatic Power-Saving Function | 15
Automatic Power-Saving Function
After 30 minutes of inactivity, the flash will automatically enter a power-saving mode to conserve battery life.
The Ready indicator light will blink every three seconds, and other indicator lights will turn off.
To reactivate the VD-420, press any button on the control panel. When in S1/S2 modes (see Optical Slave Mode
below), the flash will enter power-saving mode after 60 minutes of inactivity. During long periods of inactivity,
use the power switch to turn the flash off completely.