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I'm building my home lights with an SMD5050 Led strips. And I'm completely lost after comparing specs consumptions with real measured data.

So on, I have 5 stripes and 1-to-5 Splitter from my controller: 2 legs for 10m each, both sides fed from the splitter. 5th one is single-feed from a same 1-to-5 splitter. So, that's properly builded scheme and I don't expect

In total: 10m 30Leds/m for 7.2W/m and 15m 60Leds/m with a 14.4W/m. Oh yes, that's should be 288W and 20A x 14.4V!

I have a Wattmeter, that stands before 220V input of my 15A 12V Led power supply, and I can measure only 90W of consumption in the HARDEST case, which I mean 14.4V output of supply and White permanent color on strips. That's 3 times less than proposed to be (don't counting imperfection of 220-12V transformation).

Why so? Does it mean that I can connect more and more strips, and the power supply will handle it? (Specs for supply is 180W max consumption, so currently it's loaded just 50%).

How to figure out, where the real consumption is? I don't have a reason to untrust my Wattmeter - used it with everything in my home from phone chargers (4W) till AC (800-1200W), and collected data seemed very real..

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  • \$\begingroup\$ Welcome to EE. How much power are you measuring after the power supply? \$\endgroup\$ – vtolentino Jun 4 '20 at 13:18
  • \$\begingroup\$ The specs on led strips tend to be wrong most of the time unless it comes from a reputable importer. And even then. You should measure the voltage and current at various points of the led strips to be sure. \$\endgroup\$ – Passerby Jun 4 '20 at 14:23
  • \$\begingroup\$ My guess is your strips are too long. The resistance along the strip lowers the available voltage, especially at the end of the strip (you should be able to measure/verify this) so the strip only works at full power at the end close to the supply. What are voltages on all ends of the strips? \$\endgroup\$ – akwky Jun 5 '20 at 10:39
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This is the difference between max current (20ma per channel per diode) and actual current. If you look at the resistor values on your strip you can calculate the actual current the diodes will receive. In this case it is obviously a lot less than the nominal 20ma max for 5050 diodes.

And yes, if you have strips that drive each diode at 10ma instead of 20ma, you can have twice as many diodes per power supply.

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  • \$\begingroup\$ Namaste! Thank you for all comments, the truth comes closer. So on, I have two resistors with a "151" mark and one more with "351". Not quite sure, how to calculate final current, but going easy 14.4V / 150 Ohm = 9.6mA which is very close to \$\endgroup\$ – Nick Vad Gran Jun 5 '20 at 17:57
  • \$\begingroup\$ going further: 14.4V / 330 Ohm = 4.7mA| finally 9.6 + 9.6 + 4.7 = 24mA for 3 LEDs| or just 240mA for 30LEDs/m and 480mA for 60LEDs/m| 3.5W/m and 7W/m respectively| 140W for all my system| I think, that bottleneck is my LED controller - I figured that it's the only 3x4A but not more than 100W output, specified in manual... That's a shame, because in the description it was 192W or 144W, otherwise, I wouldn't purchase it. So, adding a few amplifiers in some points will be a good solution. And yes, now I know how to count my system consumption properly, thank you! \$\endgroup\$ – Nick Vad Gran Jun 5 '20 at 18:29

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