How much current is safe in a sealed up strand?

Greg.Ca

Apprentice elf
Joined
Jan 1, 2013
Messages
92
I am considering purchasing this particular strip:

https://www.aliexpress.com/store/product/4m-DC5V-addressable-WS2812B-led-pixel-srip-waterproof-in-silicon-tube-74pcs-WS2812B-M-with-74pixels/701799_32325613419.html?spm=2114.12010615.0.0.1u9w0b

It is a 4 meter long strip filled up with 5V WS2812b's at 74/meter. There are 296 TOTAL pixels in this strip which is sealed up in a waterproof 'jacket'. That means that there are 3X that amount of 'led's'. 296 X 3=888 total LED's. At 20ma each at full white that is 888 X .02= 17.76 amps/string.

Because these pixels are sealed up in a waterproof jacket, that means that the total number of pixels cannot be added or subtracted to. 296 total pixels in this waterproof jacketed 'strand'.

I wonder if I even fed power at both sides, Isn't that too much current for those thin little traces in the strand? Won't that eventually burn out those thin little traces if left on at full white for a period of time? Am I forgetting something or did I do my math wrong? Anything else I'm not considering?

Thanks to my 'pixel' buddies. I'm going to post this on several sites for better coverage and possibly better answers. --Greg--
 

scamper

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Jan 5, 2014
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In the description they list it as 72w roll which equates to about 14amps.
I would definitely power inject at both ends and would not run at full white for long periods.
In saying that I would assume someone did their math and made sure the copper tracks were decent enough in size.
I imagine it is going to dissipate some heat though.
 

i13

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Jul 5, 2013
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1,172
I'd expect that the voltage drop will cause problems before the heat does. The heat is a result of the voltage drop so you won't have one without the other. The pixels themselves stay quite cool.

I tried powering 5 metres of 5V dumb white strip with 60 of the 5050 LEDs per metre. It was a bit warm but not enough to concern me. The voltage drop was noticeable though.

Also note that this is a WS2812B strip so you can only have a maximum of 18.5mA per LED within each pixel.
 
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