[Jens-Christian]

My DIY LED aquarium light project has gone awry and I need your expert input!

I recently installed two strips of 5730 IP65 cheap China LEDs in my tank. I siliconed the strips to two alu rods to make it extra waterproof in my wet aquarium environment.

The first 3 days everything was bright and great but suddenly the light intensity dropped dramatically. Inspecting the LEDs I saw that each and every one of 96 led lights were roasted (brown dot in the middle). They worked but at reduced luminosity. There are a ton of parameters - wet envorinment, power converter, LED quaility, short circuit, etc. What could have gone wrong?

 

[GrampsGrunge]

Over-voltaged? Power supply has a higher voltage than the working voltage of the LED strips would be the obvious reason.

Maybe the LED strip needed some cooling and the silicone actually insulated them? Looks heat related at any rate.

 

[Nordic]

Driving a string of LEDs/power LED from a plain constant current or voltage supply is not a good idea. Without a sensing resistor their is no automatic adjustment to the resistance of the LED dropping as it heats up. Have a look at some of the nice chips on diodes.com, the datasheets have all the information required to build a unit.

 

[GrampsGrunge]

Is this the supplier?

 

[jeffkrol]

Wrong power supply

 

[theatermusic87]

silicone will insulate and without some sort of thermal grease, your aluminum rod really doesn't make a great heat sink...

 

[MCSLABS]

Use your volt meter to see if there is a continuous or noncontinuous current passing through the LED's, my guess is they got to much voltage.

 

[Jens-Christian]

GrampsGrunge, good find, the link you provided is for the exact strip I bought!
I also bought a 12V 10A power supply at Aliexpress, but I don't have a multimeter to verify the output.

Thanks for the feedback everyone. Next attempt, I will use a thermal glue (which I already have in stock but was too lazy to use) and ensure that the power supply delivers according to spec. Lets see what will happen...

 

[GrampsGrunge]

I was noticing in the 'options' from Aliexpress they have a 'waterproof' version of the LED strips, so next time get the waterproof version and just use heat-sink paste on the back side.

If you want to get really OCD, get a 4X0.8 MM tap and drill,
and some short panhead 4MM nylon screws, and secure the edges of the strip at every 3rd SMD LED. Remember to chamfer the drilled and tapped holes so you don't short circuit the strip or power-supply.

 

[Jens-Christian]

Hopefully I have found the reason my LEDs died. Maybe other DIY newbies will benefit, so here is the conclusion.

The power supply delivered 12.04v so that is no longer a suspect.

Overheating due to lack of proper cooling seems to have killed the LEDs. I underestimated the heat produced by the 5730 LEDs.

I had installed the LEDs on a light weight alu curtain rod as seen on the left. I used silicone for extra water protection (since the IP65 strip has no backside water resistance).

My new design uses a heavy IKEA curtain rod (right) with much more surface area. I have used thermal adhesive to glue the LED strip to the rod. So far this seems to have done the trick.