LED Strip lights 25M Worth

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CokemonZ

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#273339 17-Aug-2020 14:58

So - I've purchased off Aliexpress 25M of LED stripligts: https://www.aliexpress.com/item/Black-PCB-LED-Strip-5050-DC12V-Waterproof-Flexible-Led-Light-Tape-60LED-M-White-Warm-White/2033629286.html?spm=a2g0s.9042311.0.0.27424c4dp2Mcv2

They look great, but I need some help powering them.

I have a powerful enough 12V 400watt power supply, and I have power injectors: https://www.aliexpress.com/item/10pcs-DC12V-LED-RGB-Amplifier-Controller-5pcs-1pcs-3x4A-3-Channels-Extend-RGB-Signal-Control-For/32812920560.html?spm=a2g0s.9042311.0.0.27424c4d3ST36R

My question is - what gauge or mm diameter does my power cable need to be to deliver enough current at a high enough voltage at the end of the 20m run?

From my dodgy calculations: 3.6A per 5M, so 14.4A on this cable - the first one is direct connected.

I need 20m run (to get to the start of the last run).

Using this site: https://www.rapidtables.com/calc/wire/voltage-drop-calculator.html to get the voltage drop below 1volt I need 6 guage, which is huge. And even then I am not sure how I'll attach my little injector so this wire, can't use the connectors I bought when I thought I could get away with skinny skinny wire: connectors aliexpresslink

Unfortunately I can't put the powersupply in the middle, it needs to be at one of the ends.

So - any suggestions/thoughts/tell me what I'm doing wrong/how I should do it.

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#2542945 17-Aug-2020 15:15

From the title I was thinking $25M of strip lights and wondered what you were going to do with them all!

CokemonZ

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#2542947 17-Aug-2020 15:19

timmmay:

From the title I was thinking $25M of strip lights and wondered what you were going to do with them all!

Lol - didn't you hear I won lotto and spent 50% of it on LED strips :)

MikeAqua

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#2542952 17-Aug-2020 15:28

Do you need to limit voltage drop to 1%? Normally that is only done for a critical system e.g. a VHF radio on a boat.

Also have you used total length - both (+) & (-) conductors?

If I use 150 feet as total length I get AWG2 as the required wire gauge. I use the blue seas calculator. I have found it really good at predicting voltage drop.

http://circuitwizard.bluesea.com/#

Mike

nickb800

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#2542969 17-Aug-2020 15:51

Hard to say how much it will draw as the listing doesn't seem to specify. One review mentions 1.25A per 5m which 'feels' more correct than 3.6A to me.

That, coupled with a higher voltage drop as mentioned above gets you back into 'normal' cable territory.

I'd look to feed each 5m section directly from wire, as I don't think the contacts will be designed to carry 5A (and running 5A through little contacts for 20m will add to your volt drop.

CokemonZ

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#2542973 17-Aug-2020 15:54

MikeAqua:

Do you need to limit voltage drop to 1%? Normally that is only done for a critical system e.g. a VHF radio on a boat.

Also have you used total length - both (+) & (-) conductors?

If I use 150 feet as total length I get AWG2 as the required wire gauge. I use the blue seas calculator. I have found it really good at predicting voltage drop.

http://circuitwizard.bluesea.com/#

Thanks for this.

Not 1% - 1 volt drop. you are right - 1% would be crazy tight.

Interesting, the calculator I used specifically says measure 1 way, not the return journey. Yours doesn't say either way.

The calculator you used shows 6awg for 60 feet, and 4 awg for 120 both at 5% volatge drop allowance. I wonder which is right.

CokemonZ

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#2542976 17-Aug-2020 15:55

nickb800:

Hard to say how much it will draw as the listing doesn't seem to specify. One review mentions 1.25A per 5m which 'feels' more correct than 3.6A to me.

That, coupled with a higher voltage drop as mentioned above gets you back into 'normal' cable territory.

I'd look to feed each 5m section directly from wire, as I don't think the contacts will be designed to carry 5A (and running 5A through little contacts for 20m will add to your volt drop.

Wouldn't that be per LED? 3 colors is about 3x that?

MikeAqua

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#2542980 17-Aug-2020 15:59

CokemonZ:

Interesting, the calculator I used specifically says measure 1 way, not the return journey. Yours doesn't say either way.

The calculator you used shows 6awg for 60 feet, and 4 awg for 120 both at 5% volatge drop allowance. I wonder which is right.

If you hold the mouse over the length box the tip pop-up says to use total length (supply + return).

So ... the 120 feet would be correct.

I also thought 14.4A feels high BTW

Mike

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CokemonZ

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#2542985 17-Aug-2020 16:01

nickb800:

I'd look to feed each 5m section directly from wire, as I don't think the contacts will be designed to carry 5A (and running 5A through little contacts for 20m will add to your volt drop.

Do you mean strip a bit of the fat power wire and solder to that? Honestly - that's what I'm hoping to avoid - it will be hard to do tidily and then be difficult to manage.

I have 50m of 18awg that was going to be so nice and tidy :)

CokemonZ

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#2542994 17-Aug-2020 16:05

MikeAqua:

CokemonZ:

Interesting, the calculator I used specifically says measure 1 way, not the return journey. Yours doesn't say either way.

The calculator you used shows 6awg for 60 feet, and 4 awg for 120 both at 5% volatge drop allowance. I wonder which is right.

If you hold the mouse over the length box the tip pop-up says to use total length (supply + return).

So ... the 120 feet would be correct.

I also thought 14.4A feels high BTW

Super interesting, you're right.

As for current draw - I'll pull out the multimeter tonight and see if I can figure it out.

concordnz

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#2543098 17-Aug-2020 16:40

I was looking to power 17m & came to the conclusion I'd need to power it in 3 locations to reduce voltage (& light output drop) + use heavy wire. - Was 4 years ago, I'd have to dig out paperwork to see wire gage info.

I was also considering 'over volting' the power supply - to compensate somewhat (LED'S are fairly 'hardy') - I think I was looking at using a 14v power supply from memory.

richms

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#2543100 17-Aug-2020 16:51

Cheaper the strips the more often you have to reinject power to it so that you don't have drop. You will get drop on the positive line as well as the 3 negatives so can have weird interactions that make it get redder the longer down the strip you go as red needs less forward voltage.

I have some crap strips that are so thin I can see the difference over the first meter of it.

None of the cheap stuff has a constant current driver chip, just resistors so are very sensitive to voltage shifts.

Richard rich.ms

Daynger

435 posts

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#2543133 17-Aug-2020 18:00

Might work for a while but i can almost guarantee it wont last.

Most LED strip has a warning about only using in 5m lengths, including 24V strip, this is for two reasons, volt drop over the length of the LED strip making the far end duller(from memory usually started from about 7-8m on 12V strip) ,two the LED strip wont take the current needed to drive the whole strip through the first section.

TLDR: With that length you will either suffer massive dimming from about half way along or torch the strip, or both.

CokemonZ

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#2543137 17-Aug-2020 18:20

Daynger:
Might work for a while but i can almost guarantee it wont last.

Most LED strip has a warning about only using in 5m lengths, including 24V strip, this is for two reasons, volt drop over the length of the LED strip making the far end duller(from memory usually started from about 7-8m on 12V strip) ,two the LED strip wont take the current needed to drive the whole strip through the first section.

TLDR: With that length you will either suffer massive dimming from about half way along or torch the strip, or both.

That's why the power injectors, every 5m. I'm trying to figure out the size of the wire, and the best way to attach to it.

richms

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#2543138 17-Aug-2020 18:22

I have used 4mm twin landscaping cable I had lying around to get a feed out to my RGB controllers around the place. If you're using RGB amplifiers then take them all back to the controller, dont cascade them because that will lead to timing differences which shows at the low levels really badly.

Richard rich.ms

CokemonZ

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#2543140 17-Aug-2020 18:33

richms:
I have used 4mm twin landscaping cable I had lying around to get a feed out to my RGB controllers around the place. If you're using RGB amplifiers then take them all back to the controller, dont cascade them because that will lead to timing differences which shows at the low levels really badly.

This sort of thing? https://www.maser.co.nz/product/mgl212702/

Do you mean when the lights change colour there is a delay?

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