High power LEDs (like all LEDs) are current driven devices. This means that the more current you provide the LED, the brighter it will be - up to the maximum current rating of the LED. This is unlike most traditional lighting products where higher voltages produce brighter light.
This is a very important concept to understand when you are working with LEDs as most power supplies are designed to regulate voltage not current. So just connecting an LED to a standard DC voltage regulated power supply (such as a DC wall adapter) will almost certainly destroy the LED, as the power supply will provide far more current than the LED is rated to handle because the current is not being regulated. Instead, you need to use a power source that regulates the output current so that it never exceeds the maximum current rating of the LED.
Most designers use current regulating drivers between a DC power supply and the LED. The driver will then ensure that the current to the LED is never allowed to exceed the maximum current rating of the LED.
The output voltage of the DC power supply is not important, as long as the voltage is at least a few volts higher than the forward voltage rating of the LED. So, for example, you could use a 24VDC power supply to power a single LED with a forward voltage rating of 3.15, as long as you include a suitable current regulating driver between the power supply and the LED.
There are many different types of current regulating drivers, but for the highest efficiency, pulse width modulated (PWM) drivers are generally preferred. They are small, cool running and highly efficient. However they can also be somewhat challenging to design and build. So to make it easy for our customers, we offer a complete line of ready to use current regulating drivers specifically designed to power high power LEDs. These drivers are very simple to use. Just connect a DC or AC power supply to the input, and the LED to the output. The driver will ensure that the current to the LED is never allowed to exceed safe levels.