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?

  • \$\begingroup\$ There probably is, but you'd need to define "optimal" better and take a variety of measurements and measurement types to find out. \$\endgroup\$ – jonk Jan 25 '20 at 14:47
  • \$\begingroup\$ No general rule then? I defined optimal as lowest power consumption / greatest longevity to the components. \$\endgroup\$ – NibblyPig Jan 25 '20 at 15:14
  • \$\begingroup\$ You did define it that way. But you can't have both at the same time without a weighting formula of some kind. You measure quantities and "best" requires an ordering as well as a definition of the set or subset. Then measurements to be taken can be defined and preformed. \$\endgroup\$ – jonk Jan 25 '20 at 15:27
  • \$\begingroup\$ Lower operating temperature is the best (lower power dissipation and operation with in the recommended voltage range) \$\endgroup\$ – User323693 Jan 25 '20 at 15:43

The LED light you have is a Blackbox. We do not know the configuration of the LEDs (if there are multiple). The power supply internal can be a buck regulator, or even a buck boost regulator.

The LED driver IC type is also unknown. It can be probably a flash LED driver (example: STCF05)

  1. Operating a device with minimum voltage with boost regulator will increase power dissipation across the coil due to increased switching current
  2. A device operating at maximum voltage limit may have to dissipate more power across the regulator depending on the topology
  3. Independent of the input operating voltage the LED luminance intensity will be almost constant
  4. As suggested, it is also good idea to measure the input current and various voltages to understand about the power consumption
  5. Go with the datasheet. If there is a test voltage mentioned while specifying the parameters or even a typical voltage mentioned, that will be the best point to start with.
  6. If possible, even temperature can be monitored over time with fixed load condition but your mileage may vary

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