Hey guys, I am having a bit of a power/heat sink issue. Can you please give me some advice?
I am using 3m of WS2812B LED strips for aquarium lighting. I am using two, 10A, 5V power supplies (1 each to power 1.5m of LEDs). I have attached a schematic of what I am running.
I use the lights for 12 hours a day, emitting pure white light at 80% brightness. The LEDs do get a little hot and heat up the casing they are stored in a little.
So after a few days of use, 2m of the LEDs died. 1m of LEDs are left and no more LEDs have died a week later.
You guys have any ideas that could help me stop my LEDs from dying? I know I could rethink the storage case to direct the heat away but I would prefer a solution that is less invasive.
Many thanks
@Jeremy_Spencer
They are in a perspex case which I think stops moisture from getting in.
I do think it is a heat sink/power issue as I have tried with water-resistant LEDs and I found that they die faster. I think the water-resistant covering they apply to them also insulates a lot of heat!
Interesting. I’m doing something similar for my aquarium, but haven’t had similar problems. I’ve got 2812’s running at 95% white for 14 or so hours of the day, but no failures yet. I don’t have nearly as many (50 total), so maybe I just don’t have enough to make it a problem. My plan is to move to a 144 LED APA102 strip for a total of 70 lights in the future as I want to turn the brightness down to avoid power issues, but still get enough light.
@Hamish , srprisinlgy perspex isnt waterproof, moisture can permeate through it.
Are they in a waterproof silicone tube as well?
I still suspect moisture might be your problem.
Which end of the string is the failure?
Nearest the Arduino data wise or the end of the string?
As an aside, I would join the GNDs/0v as a ‘star’ configuration, rather than in ‘loops’ as you have shown. Resistance (and capacitance and inductance) is everything in grounding problems. Keep it short and sweat. There can be issues with joining in the format shown., just one end of the strip, unless you feed power from both ends.
May just be one bad chip in the string.
I don’t think you are running out of spec heat wise, the junction temp Max is ~80c not sure what that going to be at the case but if you assume half then it’s like 104f .
Assuming you buying them cheap from Alibaba it not unusually to get garbage from time to time.
@Adam_Sharp
They have died furthest from the Arduino/power. Maybe I am wrong about it being a power heat sink issue then as the current would be higher closer to the Arduino/power.
The data line between the last working LED and the first dead LED is broken.
1 is not easy to check, but 2 can be checked by pushing a logic or scope probe through the flexi compound to the dead LED ‘data in’ pin and checking there is a signal coming through from the previous LED module.
OK, I have managed to solve the issue. Thanks for the advice guys.
I was using hot glue to insulate the soldered ends of the strips. On closer inspection the hot glue had turned a little brown. Hot glue is a bad insulator! Bit of a noob mistake I know…
One of the connections must have been fried. I removed all of the hot glue. The strange part is that all of the LEDs now work WITHOUT changing any of the connections. Maybe something was shorting: could be a moisture and/or heat issue
