I grabbed this from RAPID led's led university.
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How Do I Know Which Drivers To Use?
The first decision to make is whether you want a dimmable or a non-dimmable driver. Dimmable drivers have a few advantages:
- Tweak color temperatures to your liking (if you have multiple drivers)
- Acclimate tanks more easily
- Compatible with many reef controllers (ie. Apex, Reef Angel, etc) for sunrise/sunset simulations
Once you know which type of driver you need, you’ll need to look at the current (mA) output of the driver. For non-dimmable drivers they will only output one current level. For example, the LPC-35-700 driver will output 700mA at all times, regardless of how many LEDs are attached to the driver (assuming you’re running one string in series off the driver, as opposed to say multiple parallel strings).
Dimmable drivers on the other hand have variable current levels. Please check the product description page and/or technical data sheets for the current range. For example, the ELN-60-48D driver outputs a current of 0-1.3A. Since the driver can output a max of 1300mA, this driver may be too powerful for some LEDs (ie. Red and UV LEDs can only handle 700mA) unless you dial down the maximum output current via the driver’s SVR2 knob (Mean Well drivers only).
To figure out how many LEDs a driver can run, you’ll need two pieces of information: the driver’s voltage range and the voltage required by the LED at the given current level that you would like to run the LEDs at. As an example, the LPC-35-700 driver has a voltage range of 9-48V. The XP-G Cool White LED requires 3.05V at 700mA (remember this is the current output of the LPC-35-700 driver). Thus, the minimum number of LEDs required is 9V divided by 3.05V. 9/3.05 = 2.95, thus we round up and the minimum number of LEDs is 3. For maximum LEDs, we divide 48V by 3.05V and get 15.74. We round down and get 15 LEDs. Typically we play it safe and thus on our product page we list the range on the LPC-35-700 driver as ~3-14 LEDs. Keep in mind the voltage required by each LED can be quite different so you may need to do these calculations for each of your strings."
source"
http://www.rapidled.com/led-university-1/
