The range of aerogarden hydroponics growing units changed the way they were lit a few years ago…
They moved from CFL ( compact flourescent) light bulbs to led’s ( light emitting diode)…
was it a good move?
Why would they do that…
Well there are several reasons to do it for them…and the plants…and us…
For Miracle grow, the owners, the main reason may have been cost….
Led’s are a lot cheaper than CFL’s…
Once the panel has been designed and manufactured then the construction of it and assembly of the top light housing has now become a lot simpler…
For the plants..well we need to take a quick step back and see what plants need to thrive….
What light do plants need to thrive
Most plants grow under sunlight…
And sunlight is classified as visible light …
Visible light is made up of different colors combined together…
So if you took the colors you see in a rainbow and combined them you wouldn’t be far off getting white light…
Plants have food factories ….
This is the green stuff you see as the color of the leaves…
In the fall you see the leaves of the trees change color as the food factories close down for the year and the true color of the tress leaves show through….
But most leaves while the plants are growing are green…
But this light is the light that is less used by the plant ..or reflected light…
So plants use less green light than the other colors of the rainbow….
Let’s remind ourselves what they are :
- Red
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet
And scientists have run studies into what makes a plant grow well….
What they found was that the blue color makes the chlorophyll ( the plant food factories) produce plenty of food…
And this ties in with the seasons…
In the spring there is plenty of blue light for seed starting….
And to go on to produce flowers and fruit plants are stimulated by red light….
So in the fall there is more red light ….
For plants it’s not quite as simple as that, but for simplicity sake you need blue for vegetative growth or seed starting to flowering and red for flowering to harvest…
But if you have light which covers the whole of the visible spectrum the plant can use what it needs at that time…
But are CFL’s good as hydroponic grow lights
Human sight is not as picky as plants are….
The CFL’s are created by producing ultraviolet light (UV) and causing layers on the glass to glow (phosphors) …
But these layers are each specific colors….
Our eyes combine all of these together so we see the light color as warm white ( more red ) or cool white (more blue)…
So CFL’s are not creating an equal amount of light over the whole visible or full spectrum….
And this is not brilliant for plant growing systems….
They can be used as plant growth and flowering lights…
But they are not as efficient as leds…
So what’s the crack with the Aerogarden led lights then…
If you take the CFL’s and look at the phosphor layers individually, then you would be able to produce CFL’s of specific colors ( and they do)…
Well with leds they found that they could create different color leds by adding different chemicals….
But they do produce light in a very narrow spectrum ( a very controllable color)…
So if plants respond to say blue and you produced an led which was light blue then the plants would only be able to use a very small part of the light produced to create food, if any at all…
So the leds color needs to be matched to the needs of the plants…
And luckily,as said before, scientists know exactly what frequencies stimulate plants….
And the reason you see the red and blue led grow lights is the fact that these are exactly the frequencies plants respond to most…
They do need other colors as well….
So that is the reason that aerogrow have included some dedicated blue and red leds on the lighting panel….
The white leds are really blue leds….
And then they add a coating that ‘glows’….
They can control the color amount, hence the reason you can get warm white leds ( more red) and cool
white leds ( more blue)
With leds, unlike CFL’s, they do produce a continuous or full spectrum of light, the same as the older filament light bulbs….
So they are very good for plant growth from seed to flowering….
And that is the reason there is a lot of white leds on the panel in your aerogarden…
What about changing them…
With the CFL’s you needed to replace them every season…
I know when i had them fitted i used them over two or three seasons….
You would notice a slow decline in the growth rate, then change the bulbs and be astonished at the plants response…
You couldn’t see much difference in the light color or intensity…but the plant could….
So with the cycle of the aerogarden being about 16 hours a day…
And the useful life of a CFL for plant growth being about 3000 hours ….
Then you would be looking at 3000/16 = 187 days or 6 months…
And they are not cheap…one of the reasons there are sooo many aero gardens in people’s attics doing nothing….
But with the change over to leds, then people are asking…
How often do you need to replace them…
With the average lifespan of an led at 50,000 hours and this is to 70% or 80% of its brightness…
Then you can see that they are going to last longer…
Not forever but a lot longer…and they don’t lose too much intensity…
So 50,000 hours at 16 hours a day…..
3125 days….or 8.5 years….typical life…
Some may even double that….
So do you need to replace it …nope…not yet…
They are basically fit for life…
You will find other things wear out before the leds…
But my led panel has gone wrong
This is one of the factors that are taken into account when designing the lighting panel…
I used to work in electronics designing safety equipment, so i am used to electronic design processes…
But you have a failure prediction rate….
And some led units will fail…
How you design the panel to cope with that is how satisfied your customer will be when one led failure takes out the whole lighting panel….
As there are chips to bypass a faulty led i don’t see why these could not have been fitted.. except for cost…and management…
What can you do…
If you can find out whether it is an led or the power supply then you can replace the led…or get it replaced…
If some of the leds are still on then it probably is one of the leds gone open circuit….
Why do they do this…
Well…you now have more joints in the leds…
You have two solder joints and two internal joints for the bond wires ( how they connect to the little led part inside the device)…
So you now have four joints at least for every leds …and there are about 85 leds that makes a lot of joints…
And it depends on how they are wired…most leds are wired in series …like a chain….
So if one link breaks…the chain is now two chains …and the leds go out in that chain…
How do i find out which led is out
The best way is to stimulate each led and they only work one way round….
So you need to get access to the led panel…
Make sure you unplug the aerogarden before doing any of this and you do it at your own risk…
The aergarden harvest light panel operates off 24v dc…
There are 112 leds on this panel
24 red, 9 blue and the remaining 79 warm white…
The board claims 20/25w so running at 24v the current will be approx 1 amp of current…
The board has 13 chains of leds all connected in parallel…
I am sure other models will have different board configurations…
If one led goes out in any of the chains, all of the chain will go out…
So the first task is to identify the chain…
Then if you power up the unit you can use a multimeter to test the voltage across each led in the chain…
With the chain out you, if you start at the ‘hot’ ( positive voltage) end…
Then you will get 24v with respect to the negative…
As you work along the chain the voltage will be the same until you find it going to zero volts on the next pad…
Between this and the last should be a component and this is the one that is faulty….
You now have four choices…
1. replace the board, but there is no point doing this as you have gone this far…
2. bridge the faulty component with a relevant resistor
3. replace the led ( white looks yellow, red or blue), the red ones if you look closely look like a red dot …the blue are clear…
4. add a bypass device to allow the rest of the chain to operate…
The MP4690 is one such device…
Very small and can be added in parallel with each of the leds on the board..
This way if one goes out then this device bypasses it and the rest of the chain carries on.
This last mod is really for advanced users only …or ask at your local electrical repair shop if they can carry out this modification…
Are there other options
The one other option if you led light hood goes out is to buy a grow light panel to replace it…
You will need a separate mains source and i would suggest getting a timer to set it up so that it comes on with the aerogarden and goes off with it….
>>click for latest prices ( aff link)
You could get a 45watt led panel to replace the 20-25watt one included with the Aerogarden….
This would be a versatile light which can be used to supplement natural light on other plants suffering over the short day months with indoor gardening…
So even though you may not be able to purchase a replacement led light panel for your aerogarden there are things you can do to repair or replace it…
My preference, due to my skillset, is to test and repair…
If your skills are not up to that then you have the option of replacing the panel with a larger brighter one….
If you unscrew the panel you will find a connector inside to disable the lighting panel…
I hope this has given you some insight into the led panels on the aerogarden…
Let me know if you have a problem with one and have come up with another solution….
Thanks for reading
phil
P.S.
Just looking at what is illuminating my keyboard at the moment …a thought struck me…
These leds are off of one of those strips of 10m of leds where you can cut them to length…
Feed them with 12v and they light up…
Well if you go for the 3025 size leds these are the same size as the ones on the aerogarden light panel…
If you go for the warm white ones you get a very similar light output…
>>click for latest prices (aff link)
The ones i have are the cool white , with more blue than red…
They will work better for leafy plants…
So if you intend to grow herbs, then you could replace the ones on the led panel with these and it will be more optimum for the vegetative growth…
And you can replace them as you need to….
Which shouldn’t be very often with their life of 50,000 hours…
Or if you want to make a led panel for an older aerogarden, I will have a tutorial coming up very soon to create one of these….
Let me know in the comments if this is something you want to know how to do….
I have been growing plants hydroponically since 2009. For years before that i was reading books and looking at systems and saying ...no way...
But once i had taken the plunge with the tomatoes outside, then there was no stopping me.
I tried out most of the systems and started to refine them, getting the plants to grow more efficiently.
Now I am more interested in indoor hydroponics and the challenges it presents. Being able to control the environment, feeding the correct nutrients and giving the correct length and type of lighting....
I have an LED “Harvest” version of Aerogarden and the Lights quit.
It turn out that:
Aerogarden strings the LEDs in series of 8 LEDs per string. It requires nearly something like 2.5 volts to turn on an LED, so 8 in series requires somewhere around 18-20 volts. Since the power is 12 volts, they appear to run it through a voltage-doubler circuit to get enough to light up the LEDS. Then to SWITCH them, they produce a 3 volt signal on the first pin of the 5-pin plug that goes to the control panel. It appears that 3 volts is used to trigger the “gate” signal on a “MOSFET” chip, which in turn acts as a switch to release the power to the lights. If the lights fail, 9 out of 10 times, I will bet that the electronic doubler circuit failed and the lights are only getting 12 volts (not enough to light them)…. OR …. the MOSFET switch chip has failed and the 20 volt voltage is not getting through.
The very first thing you should do when your LED light panel fails, is to apply at least 20 (up to 24) volts directly to the light panel to see if they will light THAT way, proving that it is the electronics that failed.
It is not that difficult to create your own voltage-doubler circuit using the existing 12 volt AEROGARDEN power, from diagrams on the internet… about $15 in parts. and feed it through your own MOSFET switch ($2), using the AEROGARDEN’s existing 3-volt signal to trigger it. There is lots of room down there to put the extra home-brew module.
Thanks for this information Art….
mine haven’t failed yet…
and it is usually the ancillary electronics that fail rather then the leds themselves…
but i have modified an older one to run a led panel from and external power supply…
i have had a few issues with the inrush current on the power supply and need to update the power switching relay…