Dimmable LED Driver with Non-dimmable LED's

Thread Starter

Humanist

Joined May 12, 2016
11
Can I connect non-dimmable LED's to a dimmable LED driver? I do not intend on using a dimmer. Just a switch.
 

Thread Starter

Humanist

Joined May 12, 2016
11
Thanks for the welcome. I'm trying to make an aquarium light with a simple on\off switch. No dimmer. I've got a test strip of 6 LED's which I plan to double. Please see diagram for driver and LED specs.

6 LED circuit diagram_Driver.jpg
 

Thread Starter

Humanist

Joined May 12, 2016
11
I'm a total noob to anything electrical and really bad at math to boot but it also seemed to me that it would work. However...
I've tried it twice and had two, albeit slightly different, failures.

The first time I connected the LED's they flashed briefly then died. I could not get them to work at all after that. I then tested the LED's individually and they were fine. I then connected a boost converter to the same string and all the LED's worked.

I then tried adding a seventh LED to increase the load on the driver. I connected the driver and only 2 of the LED's (first two in the string) lit up for around 10 seconds before dying.

I must also add that I am new to soldering :)
 

#12

Joined Nov 30, 2010
18,167
I'm thinking either you don't have 1 watt LEDs or you don't have a LED driver that works.
This part is difficult to interpret:
The first time I connected the LED's they flashed briefly then died. I then connected a boost converter to the same string and all the LED's worked.
The LEDs could not have died and then worked later. I must assume the LEDs did NOT die, they just stopped making light. Now that we have stopped believing the LEDs are dead, it's time to turn attention towards the Driver. What do you have for a meter? Can you measure volts and milliamps?
 

Alec_t

Joined Sep 17, 2013
10,616
For LED longevity it is not a good idea to run them at their full rated current (especially as manufacturers's figures can be a tad optimistic). About 75%-80% of that value (say 250mA) would be better. Turn the dimmer control down to about half way and get the LEDs working, then crank up the dimmer control a bit.
 

#12

Joined Nov 30, 2010
18,167

mcgyvr

Joined Oct 15, 2009
5,394
(DIY Aquarium LED expert here..built many fixtures)

Those "ARE" dimmable LEDs..

Your diagram is wrong.. The LEDs are shown backwards.. The + output from the driver should go to the + of the first LED

What are you attaching the LEDs to? do you have a circuit board?
What are you doing for heatsinking? You can quickly overheat and destroy the LEDs if not heatsinked properly..
 

GopherT

Joined Nov 23, 2012
8,012
Because the LEDs still work after connecting them to this power supply, that the power supply is shutting down rather than LEDs getting damaged.

The supply is 300mA constant current and can supply that constant current (stay in compliance) over the stated voltage range. Note that higher voltage loads will be easier for the power supply to maintain compliance and it has to dump more energy as heat when supplying a load closer to the bottom of the acceptable output voltage range. Again I am guessing without a datasheet but your power supply cannot really handle loads with such a low voltage when really designed for 50+ volts.

I would either add more LEDs in series (notice that it stayed on a bit longer when you did do that - be for it overheated), or, you can try to force the voltage drop outside of the power supply with a dropping resistor. Let a resistor drop 30 volts at the rated 300 mA. That can simply be a 100 ohm 10 watt sand-bar (100 ohm x 0.3A = 30V).

Good luck
 

hp1729

Joined Nov 23, 2015
2,304
Because the LEDs still work after connecting them to this power supply, that the power supply is shutting down rather than LEDs getting damaged.

The supply is 300mA constant current and can supply that constant current (stay in compliance) over the stated voltage range. Note that higher voltage loads will be easier for the power supply to maintain compliance and it has to dump more energy as heat when supplying a load closer to the bottom of the acceptable output voltage range. Again I am guessing without a datasheet but your power supply cannot really handle loads with such a low voltage when really designed for 50+ volts.

I would either add more LEDs in series (notice that it stayed on a bit longer when you did do that - be for it overheated), or, you can try to force the voltage drop outside of the power supply with a dropping resistor. Let a resistor drop 30 volts at the rated 300 mA. That can simply be a 100 ohm 10 watt sand-bar (100 ohm x 0.3A = 30V).

Good luck
Will the constant current circuit CAUSE 300 mA to flow or just limit it to 300 mA. Could sticking in a resistor bring the current down to 250 mA?
 

Thread Starter

Humanist

Joined May 12, 2016
11
I'm thinking either you don't have 1 watt LEDs or you don't have a LED driver that works.
This part is difficult to interpret:
The LEDs could not have died and then worked later. I must assume the LEDs did NOT die, they just stopped making light. Now that we have stopped believing the LEDs are dead, it's time to turn attention towards the Driver. What do you have for a meter? Can you measure volts and milliamps?
Apologies if my terminology is a bit vague or just plain incorrect. With all the help and suggestions I'm getting I'm learning fast though. I have a no name brand digital multimeter and I have managed to measure both volts and milliamps through the circuit. but only when I used the boost converter which kept the LED's on long enough for me to measure. Below is a screen shot of the driver.Screen shot 2016-05-14 at 9.26.25 AM.png
 

Thread Starter

Humanist

Joined May 12, 2016
11
Will the constant current circuit CAUSE 300 mA to flow or just limit it to 300 mA. Could sticking in a resistor bring the current down to 250 mA?
I did have a fleeting moment of thought and tried a 1ohm resistor in series but still no cigar.
 

Thread Starter

Humanist

Joined May 12, 2016
11
Because the LEDs still work after connecting them to this power supply, that the power supply is shutting down rather than LEDs getting damaged.

The supply is 300mA constant current and can supply that constant current (stay in compliance) over the stated voltage range. Note that higher voltage loads will be easier for the power supply to maintain compliance and it has to dump more energy as heat when supplying a load closer to the bottom of the acceptable output voltage range. Again I am guessing without a datasheet but your power supply cannot really handle loads with such a low voltage when really designed for 50+ volts.

I would either add more LEDs in series (notice that it stayed on a bit longer when you did do that - be for it overheated), or, you can try to force the voltage drop outside of the power supply with a dropping resistor. Let a resistor drop 30 volts at the rated 300 mA. That can simply be a 100 ohm 10 watt sand-bar (100 ohm x 0.3A = 30V).

Good luck
 

Thread Starter

Humanist

Joined May 12, 2016
11
Thanks! I'll give it a go too. I had a similar unqualified thought but did not add enough resistance. Will try more.
 

Thread Starter

Humanist

Joined May 12, 2016
11
(DIY Aquarium LED expert here..built many fixtures)

Those "ARE" dimmable LEDs..

Your diagram is wrong.. The LEDs are shown backwards.. The + output from the driver should go to the + of the first LED

What are you attaching the LEDs to? do you have a circuit board?
What are you doing for heatsinking? You can quickly overheat and destroy the LEDs if not heatsinked properly..
 

Thread Starter

Humanist

Joined May 12, 2016
11
Apologies for the mistake in the diagram. I will recheck the wiring. I have not made a permanent attachment to a heatsink just for short bursts for testing purposes. The LED's are kept in place with a small piece of pressure sensitive adhesive. and electrical taped the connecting wires to a piece of wood.

I assumed the LED's were not dimmalbe just because of the specs on Aliexpress which says 'dimmable: no'
And after my failures I assumed that this was problem.
 
Top