Combine Power Suplies?

Question

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

Answer 1

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.

Answer 2

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.

Answer 3

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