Jack Aaron
New Member
Hello,everyone in 420. I would like to talk about how to select an LED grow light here. Here are several tips and hope everyone here could give me some advice.
Adjustable Output Spectrum
Because LEDs are dimmable, an LED solution should let the grower tailor the light output spectrum. Look for an LED light that provides individual brightness controls for each color of LEDs. By varying the output power of individual colors, the grower can simulate seasonal light changes over a multi-week growing cycle.
For example, more blue light mimics the summer sun (vegetative phase), and more red light simulates the sunlight in the fall (flowering phase). This type of spectrum change is similar to the effect achieved by starting plants under MH lamps for vegetation and then changing to HPS for flowering. Growers can even tailor the light spectrum to suit individual plant type.
High-Power Cooling System
Like the CPU in your PC, high-power LEDs must be cooled with a heat sink and fan. Because high-power LEDs do not radiate any heat, the metal pad provides the only path for heat to leave the LED. Heat flows from the LED die, through the metal slug, through the circuit board, into a heat sink and then out to the surrounding air.
Look for LEDs mounted on a metal-core printed circuit board (MCPCB), a space-grade technology used for operating electronics at high temperature. An MCPCB conducts hundreds of times more heat compared to the typical fiberglass circuit board. An MCPCB is required for the high power levels that LED horticultural lights endure.
Finally, make sure the MCPCB is mounted to a large heat sink, preferably one with many fins. More fins provide more surface area to dissipate heat into the surrounding air. The heat sink should be cooled by multiple fans to prevent a single-fan failure from damaging the LEDs. The light’s datasheet should list the fan’s predicted lifetime.
Constant-Current Driver Circuit
The electronic circuit powering the LEDs is an important consideration when evaluating LED lights. The LED “driver” circuit is like an HID ballast; it converts AC input power into DC power at the proper voltage and current level for the LEDs. Its most important job is supplying a constant DC current even as the LED voltage changes over time and temperature.
Many simple driver circuits provide a constant voltage, meaning the output current varies with the LED voltage. A constant-voltage driver can cause early LED failure. As the LED’s temperature increases, its voltage drops, causing a constant-voltage driver to supply more current in response to the decreased LED voltage. This feedback loop results in a runaway current that destroys the LED.
Proper LED driver circuits supply a constant DC current, holding steady as the LED voltage changes with temperature. Look for the words “constant-current” in the horticultural light’s LED driver specifications.
Adjustable Output Spectrum
Because LEDs are dimmable, an LED solution should let the grower tailor the light output spectrum. Look for an LED light that provides individual brightness controls for each color of LEDs. By varying the output power of individual colors, the grower can simulate seasonal light changes over a multi-week growing cycle.
For example, more blue light mimics the summer sun (vegetative phase), and more red light simulates the sunlight in the fall (flowering phase). This type of spectrum change is similar to the effect achieved by starting plants under MH lamps for vegetation and then changing to HPS for flowering. Growers can even tailor the light spectrum to suit individual plant type.
High-Power Cooling System
Like the CPU in your PC, high-power LEDs must be cooled with a heat sink and fan. Because high-power LEDs do not radiate any heat, the metal pad provides the only path for heat to leave the LED. Heat flows from the LED die, through the metal slug, through the circuit board, into a heat sink and then out to the surrounding air.
Look for LEDs mounted on a metal-core printed circuit board (MCPCB), a space-grade technology used for operating electronics at high temperature. An MCPCB conducts hundreds of times more heat compared to the typical fiberglass circuit board. An MCPCB is required for the high power levels that LED horticultural lights endure.
Finally, make sure the MCPCB is mounted to a large heat sink, preferably one with many fins. More fins provide more surface area to dissipate heat into the surrounding air. The heat sink should be cooled by multiple fans to prevent a single-fan failure from damaging the LEDs. The light’s datasheet should list the fan’s predicted lifetime.
Constant-Current Driver Circuit
The electronic circuit powering the LEDs is an important consideration when evaluating LED lights. The LED “driver” circuit is like an HID ballast; it converts AC input power into DC power at the proper voltage and current level for the LEDs. Its most important job is supplying a constant DC current even as the LED voltage changes over time and temperature.
Many simple driver circuits provide a constant voltage, meaning the output current varies with the LED voltage. A constant-voltage driver can cause early LED failure. As the LED’s temperature increases, its voltage drops, causing a constant-voltage driver to supply more current in response to the decreased LED voltage. This feedback loop results in a runaway current that destroys the LED.
Proper LED driver circuits supply a constant DC current, holding steady as the LED voltage changes with temperature. Look for the words “constant-current” in the horticultural light’s LED driver specifications.