How to avoide voltage drop on wiring my LED strips?

Thread Starter

KasRAW

Joined Jul 11, 2020
6
Hello
Let me start by mentioning that I have little knowledge in this field.

LEDs I have: 12v 1Meter Rigid Double-row 3pin LED strips with 1.8A total draw (0.9A each row).
For some reason, they have massive voltage drop. With 12v input they measure 10.5v at the end of 1 meter and the lights seem noticeably dimmer, At 50cm it reads 11.3v. Is it normal? Wire used for testing: 10cm 2.5mm2(13AWG). Power Supply: 12V 15Amps.
I have to use the strips to light up my display cabinet(s), the cabinet has 6 shelves, each shelf is 25cm tall and 40cm long. I want each shelf to have it's individual light strip. So I will cut the strips in 40cm parts.

Now I have to find proper ways to wire the whole cabinet with minimum voltage drop, so the lights would be as even as possible. If you have any clue while considering the strips' huge voltage drop, please help.

I came up with three methods so far:

methods.png

PS: I don't know how/where to make better presenting diagrams.
 

Thread Starter

KasRAW

Joined Jul 11, 2020
6
Since editing is not available,
May I ask a moderator, if possible, to fix the typo in title (avoid)?
This post can also be deleted as well.
 

crutschow

Joined Mar 14, 2008
25,267
13 gauge wire should have no noticeable voltage drop at 1.8A.
With 12v input they measure 10.5v at the end of 1 meter
1 meter of what?

Method 1 is probably the best way to wire them up.
Method 2 and 3 show no return path for the current from the LED strings.
 

ElectricSpidey

Joined Dec 2, 2017
1,194
Is method 1 a daisy chain where each cable has to share the current with the next set? If so I wouldn't do that.

Wire them all in parallel each with their own conductors (2) to the supply.

Make each set the same length, and hide the extra length.

But as crutschow points out, you shouldn't be seeing any noticeable drop with 13AWG.
 
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Thread Starter

KasRAW

Joined Jul 11, 2020
6
13 gauge wire should have no noticeable voltage drop at 1.8A.
1 meter of what?

Method 1 is probably the best way to wire them up.
Method 2 and 3 show no return path for the current from the LED strings.
Is method 1 a daisy chain where each cable has to share the current with the next set? If so I wouldn't do that.

Wire them all in parallel each with their own conductors (2) to the supply.

Make each set the same length, and hide the extra length.

But as crutschow points out, you shouldn't be seeing any noticeable drop with 13AWG.
Sorry for not being clear.
Each lead in diagram was indicating 2 condoctors: positive and negative.
By "1 meter", I mean 1 meter of LED strip, not the wire. The strips itself have the voltage drop.

I updated the diagram making it more understandable:
methods-edit.png




Method 1 is a parallel connection, supplying each strip from both ends.

1.jpg




Method 2 is a parallel connection, supplying two LED strips at one end.
Example from web:
2.jpg




Method 3 is a parallel connection, supplying each strip individually from the power supply, at one end.
Example from web:
3.png




Sounds like the conductors making up the strip are too skinny for the current they're being asked to handle. Are they printed conductors?
Actually they are unbranded/Chinese strips.
But here's a picture:

Where I live, I have very limited access to market.
Oddly as it sounds, these were the best I could find around here.

If the drop is across the strips, you can cut shorter lengths and feed from both ends if necessary.
I think so too, they seem cheaply made.
But I suppose 40cm lengths is OK in my case.
 

Audioguru again

Joined Oct 21, 2019
1,768
If the conductors are cheap then maybe the LEDs are also cheap and will not last long.
Connect your own large enough wires from one end of the LED strip to the other end.
 

dendad

Joined Feb 20, 2016
3,595
Another thing you can do is to run the +ve wire to one end of the strip, and the -ve wire to the other end of the strip.
That way, all the LEDs will have the same voltage across them.
 

Thread Starter

KasRAW

Joined Jul 11, 2020
6
Connect your own large enough wires from one end of the LED strip to the other end.
Could you please explain more about this?

Another thing you can do is to run the +ve wire to one end of the strip, and the -ve wire to the other end of the strip.
That way, all the LEDs will have the same voltage across them.
Can you tell how much this way can differ in regards of voltage drop compared to other methods?
 

dendad

Joined Feb 20, 2016
3,595
Can you tell how much this way can differ in regards of voltage drop compared to other methods?
When you feed the +ve from one end, and the -ve the other, there is still a voltage drop along the LED strip, but it will give the same voltage across each LED as at one end, it is max +ve, and min -ve, the other is max -ve and min +ve. It equals out.
This is actually the best way to power the LED strip.
 

Irving

Joined Jan 30, 2016
949
When you feed the +ve from one end, and the -ve the other, there is still a voltage drop along the LED strip, but it will give the same voltage across each LED as at one end, it is max +ve, and min -ve, the other is max -ve and min +ve. It equals out.
This is actually the best way to power the LED strip.
What he said!

Seriously though, 2 x 20awg wires (or 16/0.2 stranded) alongside the LEDs, from one end to the other, will be more than enough. It'll bring the end volts up to about 11.95v. You don't need to go huge and you should be able to make that look neat enough.

Obviously if they're hidden from view you can use anything bigger.
 
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Thread Starter

KasRAW

Joined Jul 11, 2020
6
Notice this strip has two rows(cool white, warm white) and three leads (- + -):
20200712_034057.jpg




I will add an RGB controller to "control" the color temperature range. So it has to be three separate leads.

My question is, since I'm dealing with three wires (instead of normally two), does it affect the voltage drop by deviding current?
Because right now I'm using this online wire voltage drop calculator:
https://www.calculator.net/voltage-drop-calculator.html
One of the values is "2 conductors per phase in parallel". Is it what I need to use for my calculations?
If not, how should I calculate the wire gauge/size for this case?

Info:
Maximum wire length is 2meters
Maximum current per cable (three wires) is 0.9Amps
Voltage is 12v DC. Obviously
 

Irving

Joined Jan 30, 2016
949
The current in the individual + wires will be 0.9A, in the common - wire it will be 1.8A

That calculator asks for 1 way distance - it does the x2 for there & back for you. If you want calculate loss in one conductor, use 1/2 the length.
 
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