Save-energy mode
From The Glossary of Digital Photography
(1) A function that powers down parts of an electronic device to save energy. This function is especially important in battery-powered devices. (2) The name of a specific mode on Canon Speedlite electronic flashes in which battery drain is reduced by not keeping the capacitors charged. On some Canon flashes, the timing of this function is adjustable, while for others, the time period is set.
