LED grow lights

General Gardening
41

Maybe we revisit this later after you check out the gavita 1700e to see if I have been telling you the truth?

I also do not want to argue and think we both agree on things here. I clarified that you were correct and I meant 0.4w and not 0.4v per diode.

However I would like to point out that I think they are cheaping out on all sorts of things drivers diodes aluminum heat sinks etc. and not just capacitors.

I would also like to re state that the companies making leds that will honor their warranty are not shell companies and they are advertising why their leds are better and telling you exactly what parts are in them. Any decent led is putting out proof what parts they use and what their units produce output wise with ppfd and umol/j readings backed up by a ulbricht sphere spectrograph.

My main complaint is led companies are lying and ripping people off and filling up our landfills with rare earth minerals that should be recycled.

42

I built myself some LED seedling lights a few years ago as a project with my kids. Here is my writeup:

It is a totally feasible DIY project, so if you have the skills and desire I say go for it.

One neat thing about LEDs is that the technology gets better over time rather quickly, so if I built those lights again today they would be much brighter. If you are doing any deciding on this topic, make sure you are using data from new products, not from stuff that was made 2 or 5 years ago.

But I started wanting to try growing microgreens inside and wanted something a lot brighter in the same footprint so I tried buying a 2x2 LED grow light from Spiderfarmer on Amazon. This light works great for seedlings and microgreens.

If you want to grow full size plants indoors, I would start by looking at what people are using commercially for that purpose. I have not looked into it that hard, but it is my impression that for intensive indoor growing (mostly cannabis, but there are some urban indoor agriculture operations for high value produce) people are using LEDs more than metal halide. For the spectrum people care about you can get better efficiency out of LED, but I don’t know about for plants.

As far as flickering goes, it all depends on the driver circuits. The lights I built listed above (and most LED lights like this) used a driver that does DC/DC conversion inside at many tens of kilohertz, with smoothing capacitors on the output. So the DC output ripple (and thus cyclic intensity variation over time of the light output) was miniscule. If you run LEDs with pure DC there is no flicker.

2 Likes
43

nice writeup HollyGates

I also really like the higher CRI leds myself to. Colours just look “better” under them. Especially reds.

Your also completly right about flickering. With a good driver (like most switch mode ac/dc power supply’s. there is verry little to non existant flicker. And usualy in the kilohertz range and thus of no bother to us.
Your power supply has a maximum ripple of 200mV peak to peak. So if you could even “see” the flicker speed (kilohertz+) it would not be an “on” “off” flicker. But a bright/brighter flicker.

I have 2 notes.

not a 24v power supply.
Unlike you mentioned in the writeup. the LPC-20-700 is not a 24 volt power supply. It’s not a CV (constant voltage) power supply. It’s a 20 watt Constant Current 700mA (CC) power supply. You see that in the name to. (20=20 watt - 700 is 700mA)

If you look at the data sheet it specifies a rated output current of 700mA with a voltage range of 9-30 volt.

So it can power those 12 volt strips from anywhere between 9-30 volts to make sure it runs 700mA current. (oversimplified, the power supply starts of at 9v, and then increases the voltage till it’s supplying 700mA current and than keeps the voltage so it keeps supplying 700mA current)

It is not visible on the pictures. But i assume in the end all strips are either running at 12 volt. or you corectly put the halve strips in series and the strips are running at 18 volts. All well whithin the voltage range of your CC driver.

It is unadvisable to put CC drivers (or most drivers that is) in paralel like you did. However the diode here saves you. And was a wise choice.

Did you ever use a kill-a-wat to measure? id expect it to run roughly 17-25 watts + some for the power supplys, so in the 20-30 watt range.

Inrush current
I like to diy with electronics myself to. And have with family and kids. I however always pay extra attention to safety. Our wall power is 230 volts AC and i think yours is 120. so it goes wrong a little faster here.

If you look at the datasheet above from your power supply. It has a 70A inrush current. And you have 2. However the inrush is measured at 230 volts AC so it might be lower for you whith the lower wall voltage.

Still the 70-140 A inrush is likely way outside of the rating of the small relay in your timed switch. What makes it even worse is.
A relay is most sensitive to overload while it is switching, when there is not full contact there is a higher resistance or even a small gap that makes it possible to plasma arc. This can damage the relay contacts (internal) over time. When the contacts damage it inreases their resistance and arcing. And at some point it can burn trough.
So your not only overloading the relay. but also at it’s most sensitive time.
If your lucky it can go just fine for quite a long time. But it can also dangerously fail.
you could replace that timed switch. And either replace it with a switch that can handle the current (incuding inrush) or swap the timer for a new (non internally damaged) one and instal a inrush limiter like.

this is not advise from me, just a possibility you should look into further yourself.

https://www.meanwell.com/webapp/product/search.aspx?prod=ICL-16L#1

44

Is it worth spending more on fixtures that come with samsung leds? I see some makers advertise that but those fixtures seem higher priced.

Any thoughts on UV? Sounds like only needed when plants are flowering?

45

If you are growing fruiting and flowering plants, I would say it is worth paying more for the quality. What is the value of your crop? Does it justify the additional expense? Value is not always measured in $.
Some plants don’t like UV at all, and some need it for certain responses, like colors and trichomes.

2 Likes
46

I’ve had good results with eb strips. watching Richard and and Oscar go back and forth is like having a phd physics professor trying to teach an elementary school class, very entertaining!

everyone agrees cheap Chinese fixtures are junk, BUT many high quality components come from China…

just because a fixture is ‘led’ doesn’t make it better, there is a HUGE variance in quality and efficiency, if you are buying cheap you will get junk…

however there are many off brand producers making lights with quality components that are really good, doesn’t need to say gravita on it to be high quality…

ALSO if you don’t know how to grow under led and are used to using HID, and don’t research and adjust your methods for led growing, you will be disappointed…

LED TECHNOLOGY is simply amazing, it is causing revolutionary changes throughout our world. the diodes last for decades if implemented properly with little output loss and better spectrum than any artificial light source previously developed.

1 Like