I bought an LED light for photography, which came with a battery.
I realised later it also has a DC port for a power supply. The range is 6.5v-17v.
I happened to have an adjustable laptop power supply, which can supply 15-24v, and a couple of other adapters that do 9v and 12v.
Is there an optimal choice of voltage to supply when it comes to power consumption / longevity for a device that takes a wide range of voltage inputs?