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I'm not sure if this is the right place to ask, but I'm building something and am not sure about how to power it (I have zero electricity knowledge).

I'm building out three individually Gledopto controlled RGB+CCT LED strips for some shelf accent lighting, about 4m each.

The guide I read said that I'd need a 12V 3A transformer, but that's for just one strip+controller under 4m.

I want to run all three off the same power supply, so I don't have 3 bricks lying on the floor to hide.

Is it possible to just buy a larger power supply and add a splitter?

Does anyone have a recommendation on power supply size/type to enable me to split the power between all three controllers?

I just have no idea how to scale up power requirements.

Controller : https://www.aliexpress.com/item/GLEDOPTO-ZIGBEE-Led-Controller-Amazon-Echo-hue-lightify-tradfri-compatible-LED-controller-RGB-CCT-WW-CW/32858603964.html

LED : https://www.aliexpress.com/item/5M-LED-Strip-Light-RGB-CCT-RGBW-5050-SMD-Led-Tape-Non-waterproof-Led-Stripe-Bar/32879936721.html

Recommended Supply : https://www.aliexpress.com/item/1-x-AC-100V-240V-to-DC-12V-1A-2A-3A-5A-6A-8A-lighting-transformers/32672191071.html

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  • \$\begingroup\$ you can run all three from one power supply .... just run three sets of wires .... make sure that the power supply voltage matches the string requirement, either 12V or 24V \$\endgroup\$ – jsotola Jul 27 '18 at 2:44
  • \$\begingroup\$ I'm just unsure what size of supply i'd need, and if I can just use a spliter to send power to all three. goo.gl/tNLVFo \$\endgroup\$ – Picard102 Jul 27 '18 at 3:34
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Spec is 12W/M You have: 4M x 3.

so, 12*4*3 Watt Power Supply Unit is what you need. Ie 144W.

This considering 100% usage, you should allow some leeway, so 150W one should be good.

Connection is in parallel.

So the PSU you need is like this: https://www.aliexpress.com/item/power-supply-48v-150w-48V-3-2A-power-suply-150w-mini-size-led-power-supply-unit/891473321.html

Also, if you found a higher wattage (200W or 300W) that is cheaper, then feel free to use that instead.

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  • \$\begingroup\$ Would I then need to wire them up as a series, or parallel? \$\endgroup\$ – Picard102 Feb 6 at 18:51
  • \$\begingroup\$ You should wire them up in parallel. \$\endgroup\$ – GeneCode Feb 6 at 23:29
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If they all need the same voltage, you can add the current requirements linearly for loads connected in parallel (which is the usual way for lighting). You need a 12 V, 9 A power supply. You should assume it is not perfectly spec'd or will get hot, so a 11-12 A supply would be safer. On the other hand, the guide may have already taken this into account (it may draw less than 3 A).

The product info page overstates the power usage, so you can't use that to figure out the current. You won't know until you buy it and measure with a multimeter.

If you didn't need need controllers, you could save space and money by buying a 36 V, 3 A power supply instead. If some simple LED strips are the same model and same length, you can connect them in series and they will share voltage more or less equally. But that won't work if the controllers are doing anything interesting. I wouldn't try it.

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  • \$\begingroup\$ I think I have to plug the power into the controller, which then powers the LED's. How would I connect them in a series if that's the case? A spliter like this? goo.gl/tNLVFo \$\endgroup\$ – Picard102 Jul 27 '18 at 3:26
  • \$\begingroup\$ You definitely must not connect them in series. If you do that, and then e.g. dim one of the strips while leaving the others bright, the voltage across the dimmed strip will rise above 12V and potentially destroy it. (That's assuming you use multiple controllers -- if you try to do this with a single controller for multiple strips, you will short out the power supply.) \$\endgroup\$ – Glenn Willen Jul 27 '18 at 3:53
  • \$\begingroup\$ Each strip would have a controller. Would that not manage the power delivered to the strips? \$\endgroup\$ – Picard102 Jul 27 '18 at 3:58
  • \$\begingroup\$ You cannot connect them in series and individually control them, as the current which flows through one must flow through the other. Because these have built in control, they likely must operate as a parallel arrangement. The variety of power supplies that will work for you is truly massive. If the 8A supply on Aliexpress lives up to it's rating, there is a chance it would be adequate for the full set, you really would have to measure under full load to be sure. If it is a switched mode DC power supply, it is likely designed to have max efficiency close to max load. \$\endgroup\$ – K H Jul 27 '18 at 4:31
  • \$\begingroup\$ @Picard102 Somehow I managed to ignore the controller. The other comments are correct, you cannot put them in series and assume they will share voltage equally if the controllers are doing something different. Better not try it. \$\endgroup\$ – piojo Jul 27 '18 at 5:05
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The LED strip is rated at 12W/M. I=P/U (P = 12W and U = 12 Volt and I = Ampere).

For a 4M LED strip you need a 4A Power Supply (PSU), for a 12M LED strip you need a 12A PSU.

And you need to take in consideration of power loss in the cables, low cable area = voltage drop in the cable.

Ref.: https://en.wikipedia.org/wiki/Voltage_drop

Voltage drop describes how the energy supplied by a voltage source is reduced as electric current moves through the passive elements (elements that do not supply voltage) of an electrical circuit. The voltage drop across the internal resistance of the source, across conductors, across contacts, and across connectors is undesirable because some of the energy supplied is lost (dissipated). The voltage drop across the electrical load and across other active circuit elements is essential for supply of energy and so is not undesirable.

Calculator for voltage drop: https://www.rapidtables.com/calc/wire/voltage-drop-calculator.html

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