Evaluation of tiny LED grow lights
by /u/SuperAngryGuy of /r/HandsOnComplexity
This is a review of LED grow lights suitable for small spaces and Space Buckets, most of which are available on Amazon. If I gave the light a fail for electrical safety then the full test is not being published since I do not recommend buying the light. Some of the shots from my spectrometer may be a bit different from others since I'm showing raw images from “scope” mode.
The conversion factor is how you change the lux reading to PPFD in umol/m2/sec (which is the unit of light intensity used in botany). This is so people can spend $20 lux on a light meter rather than hundreds on a quality quantum PAR meter. The following resources are a useful reference:
- Learn how to use Lux Meters and Sensors »
- Learn more about Lux to PPFD conversions »
- Dive into Equivalent Wattage for lights »
LED Flood Lights (15.5 watts)
PAR38 LED Floor Lights (15.5 watts)
This low cost PAR38 LED light bulb was tested. Similar bulbs are available on Amazon as well. The actual wattage was 15.5 watts per light. Claimed color temperature is 3000K, but measured CCT was 3491K and 3546K. The lux to PPFD conversion factor of this light is around 74 lux = 1 uMol/m2/sec.
PAR38 LED flood lights are a simple and easy, no hassle solution to getting the lighting done for a Space Bucket, specially in a 5gal container.
Measured with an Apogee SQ-520 quantum light sensor in a five gallon bucket lined with aluminum foil (shiny side out), at six inches I got about 1200 uMol/m2/sec (about as intense of light as you want to go) directly under a light and about 800 uMol/m2/sec (good level for budding) in the rest on the bucket area at six inches under the lights. Towards the bottom of the bucket it was around 800 uMol/m2/sec fairly even. White paint or just an unpainted white bucket will have significantly lower measurements.
Is it safe? The lights only get a bit warm. These bulbs are rated for damp locations, and have an ETL Mark (they have been extensively tested for safety).
GE PAR38 Grow Bulb (32 watts)
GE Lighting 93101232 LED Grow Light
The GE Lighting PAR38 93101232 LED Grow bulb draws 32 actual watts and has a PPF of 50 umol/sec. This is a white light bulb with 665nm red LEDs although the light may appear to just be white. The PPE is 1.6 umol/joule. Lux to umol/m2/sec conversion factor is 61. CCT is 5250K.
While fine for most forms of smaller growing, its higher power output and narrow beam angle would make this unsuitable for smaller Space Buckets unless you can keep them far enough away. With a heavy heat sink that only gets a bit warm, it's important to only hang this light vertically and not use this light horizontally like one might do for supplemental lighting. You can use this light for one square foot of higher performance growing and two square feet for lower performance growing like lettuce.
Is it safe? This is one of the few small grow bulbs that is UL listed for safety. This bulb is electrically safe, but as a general warning do not put lights on a bed or the like since in some cases it can be a fire hazard. As a reference, it burned a hole through my cover after about 30 seconds.
GE Lighting 93101232 LED PPFD measurements:
- 100 umol/m2/sec at 30 inches (seedlings)
- 300 umol/m2/sec at 22 inches (basil, lettuce)
- 500 umol/m2/sec at 17 inches (cannabis, tomato, peppers)
- 1000 umol/m2/sec at 13 inches (cannabis)
GE BR30 Grow Bulb (9 watts)
GE Lighting BR30 93101230 LED Grow Light
The GE Lighting BR30 93101230 LED Grow bulb draws 9 actual watts and has a PPF of 16 umol/sec. This is also white light bulb with 66 nm red LEDs. The PPE is 1.6 umol/joule. Lux to umol/m2/sec conversion factor is 54. CCT is 4000K.
At a PPE of 1.8 umol/joule this light is as efficient as a modern HPS watt for watt. But its small size makes this light usefulness limited and is rather expensive. A major issue with this light is its wide beam angle so the light must be very close to the plant.
Is it safe? Yes! This is the safest bulb I have ever tested and only gets mildly warm. It is also one of the few LED grow bulbs that is UL listed for safety.
GE Lighting 93101230 PPFD measurements:
- 100 umol/m2/sec at 8 inches
- 300 umol/m2/sec at 4 inches
SANSI Grow Bulb (15 watts)
SANSI Grow Light Bulb (15w)
This SANSI Grow Light Bulb draws about 15 actual watts. Lux to umol/m2/sec conversion factor is 65. CCT is 6000K.
This is a white light with an enhanced 640nm red phosphor. Although I can not do CRI measurements, it is going to have a high CRI and particularly a high R9 red value. Having a high R9 value, this is actually a very pleasant light to look at for such a high color temperature. The more narrow beam angle of this bulb limits its usefulness in smaller Space Buckets.
Is it safe? Yes but the light does have fairly poor ingress protection compared to the GE bulbs and does run much hotter. Do not let any water get around this light. The light is not UL/ETL listed.
SANSI Grow bulb PPFD measurements:
- 100 umol/m2/sec at 20 inches (seedlings)
- 300 umol/m2/sec at 12 inches (lettuce, basil)
- 500 umol/m2/sec at 9 inches (cannabis, tomato, peppers)
- 1000 umol/m2/sec at 7 inches (cannabis)
UFO LED with Cree COB (150 watts)
Growstar UFO LED with Cree COB (150 watts)
The Growstar UFO Led Grow Light 150W draws about 55 actual watts from the wall. I kind of doubt that this light uses a real top end Cree COB and that is more likely a marketing gimmick to sell more lights.
The bottom line is that this is really just a generic UFO light sold by many vendors under different labels. It is cheap and has a round form factor that is useful for Space Buckets.
Inside a five gallon bucket this UFO LED will read about 1200 umol/m2/sec of light.
Is it safe? Sure, why not. It was grounded. But keep in mind that this light is not UL/ETL listed.
LED Garage Light (60 watts)
This LED Garage Light was tested. Measured CCT is 5600K. The power factor of 0.61 is awful and the apparent power (reactive power plus true power) was about 75 watts with the true power of 47 watts (residential customers only pay for true power).
When placed on top of a five gallon bucket lined with aluminum foil I read a PPFD of 580 umol/m2/sec at the bottom of the bucket using an Apogee SQ-520 quantum light sensor. That is very poor.
Even a cheap UFO will far outperform this light. With the translucent covers on this light is about half as efficient as a cheap UFO grow light and far less efficient than a quantum board with Samsung LEDs. For growing this light is a waste of power, waste of time, and waste of money.
Is it safe? Yes, but this light is not ETL/UL listed.
Not recommended: Red/Blue LED Grow Bulbs
Not recommended: Red/Blue LED Grow Bulb
I want to make something very clear about most products that are of very poor quality yet have very high reviews: it's mostly bullshit and shady merchants can buy ratings/reviews.
These types of lights are very dangerous. The two I bought had exposed higher voltages and a heat sink that was not completely isolated. Exposed non-isolated high voltage DC means that if you grab the LEDs and came in to contact with ground potential you could get a fatal shock.
I have no idea what the wattage is equivalent to. The '100 watt' light drew about 20 actual watts. Many of these lights are going to be dual spectrum red/blue LEDs only which do have a history of poor performance. These LEDs are also less efficient than a normal UFO LED or a normal white LED light bulb watt for watt.
Since I strongly recommend against this type of light I will not post my measurement results.