Discussion in 'DIY Forum / Technical Articles' started by screwdriver, Jan 7, 2017.
Here is a new test plant. Another saved from the trash can.
Screwdriver you're insane! You're going to make an electrician out of me in no time. So, my constant current drivers keep me from having the heat issues you're talking about? What's a good brand multimeter? All I have is a cheap one from harbor freight.
Here's some more pics of the light on. Really bright for 84w(probably a lil less once I get some readings on it).
No,no,no. Well, maybe in a roundabout way in the last no. By using the constant current power supply of 600mA you have restricted the amount of heat that will be created by the LED. Also, the heatsink has sufficient surface area and a fan to dissipate alot of heat. So in your case, yes, using that 600mA constant current driver is keeping the LED light cool. BUT, if you used a 1500 mA constant current drivers, you may not be able to dissipate enough heat with that heatsink and fan. Then the LEDs run a little hotter causing possible damage. Many benefits to keeping the LED cool.
With most stuff, the cooler it runs the better. Including the drivers.
In the LED driver for the first string . The output max is 48vdc @600mA. Working at the max power it will put out 28.8 watts. Lets look at the input, 110-265vac and .2 amps. Which works out as 24watts. Well, the above math aint cool, input 24watt, output 28.8watts. You can't have more output than input. So, I assume it to be about 24watts power in that package. Do you want to use it at its max rating or do you want to dial it back a little? I think of heat, if it will be in some cooling path, is there other little heaters mounted near it, whats the ambient temp where it will be located. A bunch of stuff. Maybe I would drop it to 80%. That 24 watt power pack now is used at about 20 watts of total output power.
The second driver, max output of 27watts. We have missing input information to help us decide. So I can guess a max of 25-30 watts. Other information: Some thermal specs TA:50c(max), I take that as the maximum ambient temp this thing wants to live in to work right. 122 farhenheit. (Whats the temp inside that sealed black box mounted on top of the light where the temp is highest on the light) With assumtions of heating the max output of the driver drops to the 25watt mark for me. And 80% of that is 20watts.
The above is just my start guess design, by the time the project ends I would expect the design to draw about 40watts of power for the lights. An extra 10 watts to generate the 40watts. Plus an extra 5watts for the fan. For a total of 55watts from the wall. That should be about 2.2 amps draw on that house circuit.
I think your design uses a little more power. My guess is 56.88watts total power to run your light with 41.88watts of energy going toward making light. Of that, most is still heat.
Your little heaters can put out more light but they will get hotter.
Meters. If I was rich, I would get a Fluke. I like how the name sounds, I like the colors they use in their design, I like the shape and features. They are far more accurate than harbor freight meters. If you get them calibrated regularly and take care of them. I buy cheap harbor freight, or the Depot meters because I don't need 3.5 decimal accuracy or anything fancy. I just need a semi close indication of accuracy.
You've really got me thinking now. Time to buy me a few different drivers and see how bright I can get this light and still control the heat. Right now...there is zero heat. The light doesn't even get warm. I did think my drivers were 700ma until I started putting the light together.
Got the 5 watt LEDs today. And visible difference but the same size.
Start off by using a little flux. Check the polarity. In this design, I didn't make all the LEDs placement direction the same. I marked the positive and negative sides on the circuit board, rechecked, then started over to make sure I had the LEDs placed correctly before I started to solder.
Action shots. First solder to board, clean all the excess flux off the board with alcohol, position heatsink on board and tighten down. Resolder the LEDs.
The last step was to set the backs of the LEDs flat against the heat sink.
All the LEDs are soldered to the board. Cut those black squares and put between the heatsink and LED back. Its a double sided thin sticky tape that is supposed to aid the transfer of heat to the aluminum. Not the best product but OK.
Here's a pic of the LEDs in action and in the cool tube just as I turned it off. Its too bright for my camera phone, the pic comes out all blurry.
Even though its bright, I checked the current on the strings and they were all low. My power supply just didn't cut it. I have to go out and get a new one then I'll have more specs on the light.
This is the completed light from trash and left overs. All the LEDs are super glued to the heatsinks. Doesn't feel that warm. The hottest spot on the heatsink is on the silver heatsink right above the "full spectrum" LED. 106 F.
Here's the schematic for the little light with voltage drops and currents. Starting on the left of the image. The power pack in use had a .23A draw from the wall which worked out at 27.6watts. The power packs output with the LED load is 12.71vdc at 1.1A. I measured the total current draw of the circuit by unsoldering the connection in the above picture and placed a meter in line. The meter was set to read for current. The other currents were measured doing the same thing but in different areas of the wiring.
The voltage drops were measured across the LEDs and resistors.
Testing in cool tube. Temperature of the center heatsink is about 18 degrees above ambient.
Plenty of action down below.
The leaf that was closest to the light seemed to be curling more. It was about an inch from the light. I don't see any damage to the leaf just the curl. I think the light should kept no closer than 2 inches above the top of the plant.
So if you start out growing a plant that is green then it changes color to purple in its natural growth cycle, should the light spectrum change to maximize growth when the leaves are purple?
I cut the hours of the day from 20 to 14 and the flowers started popping thru the canopy. Ready to set it out in the real world. May not see it in the picture but the colors seem more vibrant then before.
Here is the first failure on my veg light made with the 1 watt LEDs. A circuit of 6 blue LEDs went out. You can see from the picture below that there was a little current flowing thru the burnt out LED causing the other ones to dim. Easy enough to diagnose and repair. Removed the bad LED, replace and test.
It probably took longer to remove the mounting chains than to resolder the new LED.
My little 40 watt veg light seems to be working better than the old 70 watt mh. I had couple of blue LEDs burn out so I just solder a wire around the LED. I think the cause is cheap LED but it could also be the heatsink design and the LED maybe overheating.
What I have noticed.
The leaves feel thicker.
The colors really pop out. (My begonia flowers are more vivid than the flowers that bloom in my front window)
The internodes are tighter, maybe too close but the plant grows perfectly for the size of my flowering cabinet.
Less power to operate
Less heat in the grow area and easier to manage.
I'm sold on my LEDs for vegging.
I am stepping out of my little cabinet and into a little bit bigger tent in a closet.
I found a computer that was going to the recycler so I grabbed the heatsink from the cpu. In this use I wanted different airflow so I popped the fan off and flipped it over. Now the air is pulled thru the fins by the fan, then into the duct going outside the tent. The fan is powered by a power pack from an old router from cable company. I never seem to throw away the power packs. Anyway, it is a 12vdc @ 1.0amps, the fan is a 12vdc @ .7amps
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