Advice Regarding Chaining LED Strips

Question

I recently purchased five LED strips online (these specifically: http://www.ebay.com/itm/331059064977) to hang up along the outline of my room. Each strip is 5m (16.4 ft.) long, requires 12 V DC to power, and dissipates 0.08 W/LED.

Each strip dissipates 48 W, meaning that at the recommended 12 V DC, there would be a current of 4 A.

I planned on soldering the five of them together in series so that I could have one long chain of LEDs that will only require one power source. However, I am slightly confused regarding what adapter I should purchase that will power the chain.

Each strip seems to come with two cables attached to both sides (power and ground); I'm a little confused regarding this, because I know that LEDs should be forward biased, so why would both sides require power and ground?

Also, because I will have five strips, should I be passing 60 V DC through the entire thing if it's recommended to only pass 12 V DC for each strip? I just want to make sure that I don't blow anything up accidentally by exceeding the maximum rated amperage (I probably wouldn't want to go over 4 A if possible).

Answer 1

If you hook them up end to end, you need just 12V, but at 5 times the current.

The strips actually have a circuit something like this (imagine the vertical resistor-led combinations between 12V and GND are repeated, going off for 5m):

^{simulate this circuit – Schematic created using CircuitLab}

It may actually have multiple LEDs per vertical section (to avoid needing a high power resistor), but the principle is the same.

So, hooking them end-to-end is actually hooking them up in parallel. This arrangement is also how you can cut these strips without breaking them: You're just removing parallel LEDs from the chain.

So, just get a supply that supplies 12V at 20A.

Alternately, if you don't want to hook them up end to end and instead want to hook them up in "parallel", you are actually hooking them up in series and would require a 60V, 4A power supply.

Answer 2

These strips are composed of multiple parallel segments of three series LEDs plus resistor. When you add multiple strips together they are still in parallels so the voltage does not change. You want a power supply that's exactly what you will already said, 12 volts at 4 amps or higher.

Keep in mind that flexible printed circuits like these LEDs are on have a high resistance so the voltage will drop the farther down the line the LEDs are from the power source. The ones at the end will be less bright. Ideally you would provide power every five meter section, with a parallel connection using regular wires.

Answer 3

Due to the limit of 3 cascaded strips, series cascade operation is not an option and rather separate AWG 16 wiring from power source to a group of 3 or less.

I would suggest 4 strings with 48V to 56V with 5A supply and a PWM dimmer so your eyes are not blinded. 12V strings are usually design to run at 14.2V auto voltages. This way the current does not add.

But if you use an ATX supply rated for 20A then use no more than 3 in parallel cascaded strings as the 1st strip conductors will get warm and drop voltage.

Use "star" central wiring instead to either end.

DO NOT CASCADE 5x 48W LEDSTRIPS in parallel END-TO-END

Either connect all at same end with heavier or =AWG 14 or use AWG 16 to each LEDSTRIP or use series higher voltage. but any PC ATX 500W ought to work as long as cables are not too long for voltage drop.