You can’t just connect any LED to any power supply. Unless you’re sticking to plug and play kits, you’ll need to know this skill before starting a DIY build!
Congrats on taking your first step to becoming a true DIY LED Grow Light Builder! If you’d rather not learn this stuff, DIY friendly LED companies (and this website) will list compatible drivers for their LEDs. Check out the LED Modules and LED Drivers pages.
After reading this guide, if you have questions contact us! You can also read the related expertly written guides by LEDGardener.com, links at the bottom of this post.
Once you understand this guide you will have the skills to:
- Calculate the right driver for any LEDs, or
- Calculate any LEDs to fit a driver you might already have.
This QRG covers
- A (simple?) step by step guide for both driver types: Constant Current (cc) and Constant Voltage (cv).
- How to look up the specs on the LED and LED Driver data sheets (with links!).
Matching LEDs with constant current drivers:
- Less chance of damaging your LEDs.
- Can use different types of LEDs on one driver.
- Will not get 100% available power from the driver (but usually can get pretty close).
- More complicated to add LEDs once you’ve maxed out the driver (covered in the advanced series and parallel wiring QRG).
Steps for matching LEDs to constant current (cc) drivers:
- Step 1: Figure out how much power you need.
- Step 2: Find your LED’s forward voltage (Vf) and current ratings.
- Step 3: Figure out what current you want to run the LED’s at.
- Step 4: Find a driver that matches your selected current with a max out voltage is close to but less than the sum total of all LEDs.
- Step 5: Confirm the LEDs fit the driver.
- Step 6: Wire the LEDs to the LED Driver correctly!
- Figure out how much power you need. See the How Much Power do I need? QRG. For our example we will aim for 300W in a 2×4 tent.
- Find your LED’s forward voltage (Vf) and current ratings. Check the manufacturers website or data sheet. Look for the typical/recommended current (running LEDs at absolute maximums will get really hot, shorten their lifespan and run less efficient, or running at minimums will be highly efficient but you will need to buy more LED modules). See the LEDBuilder.org LED voltage/current database. Since using a CC driver we can mix and match LEDs, we are going to try ChilLED Logic Pucks on top (48Vf/2300mA max) and PLC Photo Boost strips as side lighting (28Vf/1900mA) together on one driver.
- Figure out what current you want to run the LED’s at. CC drivers typically come in 700mA, 1050mA, 1400mA, 1750mA, 2100mA and 2800mA. Since the recommended voltage for the PLC strips is lower than the pucks (1400mA), that’s the current we will pick. This will run the pucks lower than typical power which increases their efficiency.
- Find a driver with selected current at or above the total wattage you need from step 1. We will look for a 1400mA (or 1.4A) driver around 300W. Meanwell makes reliable high end power supplies, and their HLG series is a good choice. Check Meanwell’s website for a suitable model, or use the driver matching database (coming soon) instead. We found a potential option: Meanwell HLG-320H-C1400
- Confirm the driver’s max output voltage is close to but less than the sum total of all LEDs. We previously decided on the current (1.4A). Now we need to check how the LEDs fit the drivers maximum output voltage. For constant current drivers add the LED voltages together until you get close to the driver maximum output voltage (but don’t go over!). For this example the HLG-320H-C1400 max output voltage is 229V. Let’s try three pucks up top and three strips for side lighting: 48+48+48+27+27+27=225V Perfect! The LEDs take 225V and the driver can provide 229V. That’s a good match! You don’t want to match the LEDs to the max driver voltage exactly, you should always leave a few extra volts on the driver side.
- Wire the LEDs to the LED Driver correctly! Wire your LEDs in series when using a constant current (cc) driver. See LEDGardener.com’s article Wiring LEDs in Series and Parallel for more info!
Bonus tip. To figure out how the wattage is being spread out, multiply the led voltage by the current, for example:
3 Logic pucks x 48Vf = 144Vf x 1.4A =
202W of top lighting
3 PLC strips x 27V = 81V x 1.4A =
113W of side lighting
Matching LEDs with constant voltage drivers:
Pros to using a constant voltage (CV) driver:
- Can get all available power from LED driver.
- Can keep adding more LEDs to reduce heat and improve the light spread or coverage.
Cons to using a constant voltage (CV) driver:
- All LEDs must be identical.
- Potential risk of overloading LEDs if a connection gets loose or (unlikely with high end components that have been properly cooled) an LED fails