How best to power 140 lighted signs that require 5v ~.3amp

Thread Starter

hairless hippy

Joined Jan 22, 2020
4
I have a side hustle where I sell signs that are on display. they all require 5v and if you asked the manufacturer they say .5 amp but I've tested and really only about .3 amp.. I have 140 signs.. so thats like 210w..

I currently use a computer power supply connected to 40 separate USB ports which seems to work.. problem is, it drops below the 5v mark when all the signs are up and running.. so maybe 20 signs per computer power supply? or should I run buck converters on the 12v rail to get 5v out of them too? is there an easier way??

what do you think about this link? if I used 6-10awg wire as main trunks I could probably get the current I need.. but yes.. its a cheap chinese power supply.. I should stay with the computer power supply idea and make more of them? I've also have a few 5v 2amp wall worts where I solder a USB port every 12 inches or so and make my own USB 10 port hub.. but keep in mind.. the more power the brighter they are.. and my events are often outside.. thank you in advance..

https://www.ebay.com/itm/300W-5V-60A-AC-DC-Regulated-switching-power-supply-for-LED-Strip-Light-Display/152778823325?_trkparms=aid=111001&algo=REC.SEED&ao=1&asc=20160908105057&meid=661e774ea1e04b97850390cdd5c5fd5f&pid=100675&rk=2&rkt=15&mehot=none&sd=274209808831&itm=152778823325&pmt=0&noa=1&pg=2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci:58851052-3ca4-11ea-9871-74dbd1802fcd|parentrq:ca66870816f0a9c120b1b62fffe09939|iid:1


ohh and I use a honda 2200i inverter generator to power them..
 
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Alec_t

Joined Sep 17, 2013
10,920
Welcome to AAC!
I'd go for more computer power supplies. They're relatively cheap, or can probably be salvaged locally.
 

dendad

Joined Feb 20, 2016
3,330
I'd add a buck converter to each sign so you can run them on a higher voltage and not worry about the voltage drop over the cables.
3A buck converter.jpg
Similar to these, they are available in fixed and adjustable versions. And at about $1 each, not a bad price.

Here is another version...
Buck_s-l1600.jpg
This one looks to have a max input voltage of 16V. The first one is quite a bit higher. Have a hunt on Ebay or similar.
 
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Thread Starter

hairless hippy

Joined Jan 22, 2020
4
I'd add a buck converter to each sign so you can run them on a higher voltage and not worry about the voltage drop over the cables.
View attachment 197437
Similar to these, they are available in fixed and adjustable versions. And at about $1 each, not a bad price.

Here is another version...
View attachment 197438
This one looks to have a max input voltage of 16V. The first one is quite a bit higher. Have a hunt on Ebay or similar.
I like how you think.. I'd have to have one for every light but it would guarantee correct voltage while being most efficient.. I can get them for about 80c usd each.. a very possible option.. thank you..
 

dendad

Joined Feb 20, 2016
3,330
Just ensure you set them to 5V, and test them before hooking up the LEDs.
They are great little devices. I use them quite a bit :)
An extra thought, if you feed them via a bridge rectifier, then they are polarity free too.
 

Thread Starter

hairless hippy

Joined Jan 22, 2020
4
Just ensure you set them to 5V, and test them before hooking up the LEDs.
They are great little devices. I use them quite a bit :)
An extra thought, if you feed them via a bridge rectifier, then they are polarity free too.
I have 8 rows of 18 lights.. I'd run one of these step down converters per sign.. I'd have to solder a USB port on the output of each converter so sign would plug in.. would I run 1 trunk for every row of 18 signs, 8 trunks total? each trunk would be 12v and maximum current at 12v would be less than 3 amps for 18 signs (.3 amp each).. so I'd maybe have 2 PC power supplies putting out 12v and providing less than 12 amp per power supply to power 70 signs each. right?
 

dendad

Joined Feb 20, 2016
3,330
I would use 1 regulator per sign myself. But if you don't want to do that, run maybe 5 or 6 signs per regulator. It is always a good idea to not run devices near their maximum rating.
And use something like these as the power connectors.

2pinPlugSocket381.jpg
 

Wolframore

Joined Jan 21, 2019
1,669
those switching regulators are handy but don’t trust their rating. I would not run them over 1A and actually would use one per unit for better efficiency. As the current goes up the efficiency drops, the unit heats up and regulation suffers... the 2-3A rating they claim should be considered a peak rating. They are most efficient at about 100-300 mA.
 

Thread Starter

hairless hippy

Joined Jan 22, 2020
4
Thanks for the suggestions and the help.. I am going to document this so maybe you can continue to help or we can help someone else with the same problem. I bought 70 of these modules.. https://www.ebay.com/itm/112619038572 I am either going to buy another 70 and do 1 each sign or try to do 2 for each sign.. I contacted the manufacturer of the module and they said this, "normial 2A, 3A is max, can't use long time". Now we all know even when they say 2A nominal they really mean about 1 amp.. the thing is my signs specs say .5 but in reality they go max to .3mAh. so maaaaybe I can run 2 signs per 1 module without a problem.. they are cheap so will buy more if it needs it.. while I am thinking this through some other questions came up and I just want to put it on paper and think it though here.. please let me know what you think or if there are any improvements you can suggest.. Thank you!!

so I have basically twice the display of signs you see in the attached image.. side by side. 8 rows up and 18 signs across. 144 signs each requiring 5v @.5mAh. If we broke it in 1/2 I would put 36 modules on the bottom tables of 72 signs and 36 modules on the top tables of 72 signs.

next concern. do I solder 2-USB connectors to the output of each module or solder the wires right to the board.. I may be inclined to go with a double usb header so I can remove bad wires easily and I think for transport its better too.. Also how can I MOUNT 72 modules so they dont fall on each other or short out and become a giant cluster fu*&.. I'm thinking I either need to mount them to a board or even 3dprint/create some type of enclosure for each module so they are safe and out of the way..

144 signs @ 5v .3mAh = 180W 180w/12v = 15A so does that mean each trunk should be capable of 7.5A (one per 1/2) in which all of these modules would plug into?

Does that also mean that ONE computer power supply providing 18A on 12vA and 18A on 12vB should be able to power all 72 modules without a problem?

I'm thinking of a box around a power supply with power port, venting and 2 plugs each providing 12v to 2 separate 12v trunks

I'd also have to find the best connector to use for the 72 connectors on the 2- 12v trunks for where the input of the modules plug in.. is that what I'm really going to have is a 12v wire with 36 connectors on it where the modules plug in?

sorry for the overload of info.. hope this all makes sense..
 

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Wolframore

Joined Jan 21, 2019
1,669
Just remember there are losses also so it's best to over spec the input power supply. Without measurements, it will only be a guess. Try two or three modules per converter and monitor for heat and voltage stability. We have no idea if those will be 70 - 80% efficient or less??, keep in mind that that as current goes up what's not converted will generate heat. 15A @ 12V supply with 100% conversion efficiency isn't realistic. Your converter efficiency is complex which is affected by Vin, Vout and current draw, switching supplies are designed for a certain sweet spot.

Here's the datasheet for your converter but it will not tell us much for your particular circuit that you will be using.
MP1584

You will have to do some testing, start with the 70 that you've ordered ... you may find that it's enough. You may want to use two or three branches, again, test your results.
 
I agree with Wolframore on "two or three modules per converter", with a leaning towards three. The MP1584 datasheet efficiency curve maxes out at about 85% for 1-2A loading with 12V in and 3.3V out. It's best to run the supply near its maximum efficiency point, and likely efficiency is even better at 5V out. Mount each module solidly on a sign, hard wire it, and add two USB receptacles to support a sign on either side. Your power source will need to supply up to 56W per row of 18 signs, or just under 4.7A. That would be an easy feed with 18ga wire per row, and three rows fed from a single 12V 150W supply. Yes 3x56 is more than 150, but you already know the signs run a bit less than the specified 0.5A used for the 56W number.
 
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