Tried to make my own grow light- Lights just flash?

[FailBoat]

Hello, I tried to make my own grow light (an add on light) put everything together and the lights just flash?

Parts used:
8x red 3w 10pcs 3W Red 80LM 650nm 660nm LED Plant Glow Light DIY | eBay

4x blue 3w 10pcs 3W High Power Royal Blue 452 455nm LED Emitter 45mil Chip | eBay

9-12x3w led driver: Waterproof 670mA 36W Power Constant Current Source LED Driver (85~265V) - Free Shipping - DealExtreme

Cheap 12xSpot in series PCB from ebay (going add heatsinks/a fan just testing it out atm)


I Google around and it seems when it flashed the voltage is wrong but I did the math and it should work?

8x red would be 17.6-19.2v DC Forward Voltage: Typical: 2.2V Max: 2.4V
4x blue would be 12-13.6v DC Forward Voltage (VF): 3.0-3.4Vdc

so would be 29.9-32.8v and the driver output voltage is DC28-45V.

I don't understand whats wrong.


/edit
I let it sit un-plugged for while plugged it back in and it worked.

Unplugged and plunged back it and again flashing.

NOTHING is wrong with the plug socket/plug in
*110-120V US voltage*

Seems to be a 20% chance the lights will stay on (or stay on within a few sec of flashing).

/edit 2
5 out 5 tries it stays on within 2 mins of blinking but WHY is it blinking just a cheap driver?

 

[LEDBud]

Did you wire them in series or parallel ?


Strings of multiple LEDs are normally connected in series. In one configuration, the source voltage may be greater than or equal to the sum of the individual LED voltages; typically the LED voltages add up to around two-thirds of the supply voltage. A single current-limiting resistor may be used for each string.

The other configuration is to run the sum of the supply voltage at approximately 75 — 85% of the combined LED voltages.[citation needed] This uses the LEDs' combined inherent resistance as a serial resistor. While small voltage drops to each LED generally make no discernible loss of intensity or brightness[citation needed], with sufficient LEDs in series a noticeable drop in brightness begins to show with enough LEDs in the circuit. In assuming that the supply voltage is 12 V, and each LED is 3 V, by using a string of either five or six LEDs whose combined voltage is 15 V or 18 V, they effectively may be under-driven, in favour of absence of power losses in terms of waste heat from resistors as well as simple circuitry.

Parallel operation is also possible but can be more problematic. Parallel LEDs must have closely matched forward voltages (Vf) in order to have similar branch currents and, therefore, similar light output. Variations in the manufacturing process can make it difficult to obtain satisfactory operation when connecting some types of LEDs in paralle

 

[Antics]

Isolate the driver and test it. If you didn't change the wiring, and plug it in and it works,, unplug it, and plug it back in and it's flashing, it's not the wiring or diodes IMO.

 

[FailBoat]

Did you wire them in series or parallel ?

series, It's a PCB with the wires built-in.




How would i test the driver?
*Newbie here with no real testing equipment but its it's cheapish might buy it*

At this point I'm pretty sure it's the driver it was the cheapest I could find and being from China it's not worth sending back for refund/replacement.

 

[Antics]

You should be able to use a multimeter on a DC voltage setting, (also sometimes called a DMM) with the probes on the leads from the driver, and the meter will show you voltage fluctuations, or on/off spikes, the way the LEDs were showing you.

 

[FailBoat]

One like so: New DT 830B 3 1 2" Palm Size Digital Multimeter Voltage Meter AC DC Tester | eBay would do?

Much cheaper then I expected.



I think the driver will do for now. A few minutes of blinking a day isn't a big deal but it'll probably die at one point then I'll replace it with a better one.

 

[Antics]

One like so: New DT 830B 3 1 2" Palm Size Digital Multimeter Voltage Meter AC DC Tester | eBay would do?

Much cheaper then I expected.



I think the driver will do for now. A few minutes of blinking a day isn't a big deal but it'll probably die at one point then I'll replace it with a better one.

Yes, that's all you need, and will more than likely use the 20 V DC setting to test the driver.

A few minutes of blinking each day over your plants can cause problems, such as premature flowering, or light induced stress, causing them to hermy. Light problems, such as an incorrect schedule, or light leaks are the most common cause of a plant hermying, so it's definitely a big deal and something you want to avoid.

Sometimes it's easier to buy a product, rather than build one. I was going to build my own light, but for the cost of materials, it ends up cheaper to buy one, than build a light of the same specs.