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Manufacture stated to run 12v 5 amp per 5m led. Im going to be running 7.5 meter, which is using 1 set plus half another. From research its suggested to go to 24volt power supply. Question 1 is can I connect the 2.5 m strip to end of the 5m without any real issue and push current that far or do I need to wire the 2nd strip back to the power supply? This is going down a 24 foot walk in closest so dont really want to run 2nd set of wires back. From my calculations a 24v 7.5a should supply this 5630 dual row led 120 led p meter. Is there any flaws in the above logic, or can I safely run a higher v power supply. I want to be able to leave these one all time if I chose to.

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  • \$\begingroup\$ Im aware of AC current, 16 watt led on a 110v, only pulls the current needed. Im just not that familiar with direct current. The question is if 24v 7.5a i required to power completely, is there any issues with using 24v 15a to 20a so that its a lower draw on the transformer? \$\endgroup\$ – Billy Berry Jan 3 '16 at 19:50
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    \$\begingroup\$ If the LED strip is designed to operate on 12 volts, you MUST NOT try to operate it from a 24 volt supply. Using a 24 volt supply would almost certainly destroy the LED strip. \$\endgroup\$ – Peter Bennett Jan 3 '16 at 19:55
  • \$\begingroup\$ Color:White View angle:120° Working Voltage: DC12V LED Type: 5630 LED LED Quantity: 600 leds/5 Meter, 120 led/Meter Luminous Flux: 1200Lumens/Meter Output power: 28.8W/Meter,144W/5Meters Working Tempreture:-20 to 50° Protection Rate:Non-Waterproof Long life span: 100,000+ hours Certification: CE and RoHS \$\endgroup\$ – Billy Berry Jan 3 '16 at 22:33
  • \$\begingroup\$ This is all the specs given, supplier did respond 12v 5 amp per strip, Im using 1.5 strips so 12 v 7.5 amps is what is required to power it. I want to leave these on without worrying about burning up power supplies. I need to connect the one strip to the end of the other so the strip itself will be 7.5 meters one piece long. So can I run 24 volt or do I have to go back to 12v? I see people running multi strips from the power supply, I just want to run one lead set out from the ps to run one long 7.5 meter strip. \$\endgroup\$ – Billy Berry Jan 3 '16 at 22:37
  • \$\begingroup\$ Can only edit for 5 mins, let me correct above on power requirements. This is 144 watts per 5 meters, 12v 10amp per 5 meters thus project requires 12v 15 amp to power 7.5 meters, and will be rated at 216 watt. Now is it safe to use a larger power supply like a 24 v 30 etc? If so what is recommended, the above is required, but its not to know this wont last running 24 hours a day if needed or left on. \$\endgroup\$ – Billy Berry Jan 3 '16 at 22:48
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Without having extremely detailed specifications of the LED strip and what you consider to be acceptable the answer cannot be determined.

Connect it to the end and see if it gives acceptable performance, I would expect that it will. if it does not (light too dim at the far end) you can then add a cable from the junction, (or move the power suppply to the junction) etc.. use a 12V power supply capable of 7.5A pr more, there's no simple way to use 24V with that setup.

ideally you should connect power to the strip at several points.

eg: by running a cable parallel with the strip

You may find that it's possible to drill a series of holes in the ceiling and fish the supply cable through them, and then fix the led strip such that it conceals the holes

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  • \$\begingroup\$ I really need this power supply to be at one end of the 7.5 meter strip. This is a very low ceiling height walk in closest. No head room, thus why im running these leds. Closet is 24 foot plus few feet on expansion part. I reposted above all I have from the manufacture. Im more than sure the 12v 15 amp power supply will work, but I to know if I have to stay with 12v or can use 24v, and how high is acceptable to run on ps amp wise. I need this to be able to stand running prolonged periods of time. One set will not be turned off months at a time. \$\endgroup\$ – Billy Berry Jan 3 '16 at 22:49
  • \$\begingroup\$ To reduce voltage drop along the LED strips, you should run two conductor (+12 Volts and ground) #14 or #16 wire along the LED strip, connecting to the power terminals on the strips every five feet or so. \$\endgroup\$ – Peter Bennett Jan 3 '16 at 22:58
  • \$\begingroup\$ @BillyBerry yeah, what Peter said. if you can't run the wire above the ceiling run it behind or beside the led strip \$\endgroup\$ – Jasen Jan 3 '16 at 23:01
  • \$\begingroup\$ Lets go to next subject on ps. Say I run 7.5 feet, I will run power basically every 2.5 meters (3 connections). Ok, once again Im not that familiar with the laws of dc current. As long as the ps is 12v 15 amp, can I just run 3 wires from the + and - to the strips and it evenly distribute the power? Or do I have to put some resistors etc inline as well. \$\endgroup\$ – Billy Berry Jan 5 '16 at 1:10
  • \$\begingroup\$ yes, just like that, I suggest you test it out before you install it. You say the strip is 5A per 5m, so a supply of 7.5A or or more will be sufficient. \$\endgroup\$ – Jasen Jan 5 '16 at 5:11
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Question 1, yes, you can just add on the extra 2.5 Meter section to the end of the 5 Meter section. But even brightness is an issue due to the poor resistance of the FPC the tape is made of. See last paragraph for the solution to this.

Question 2, The highest you should ever run a simple 12v led strip is 14V. The average strip will power the leds with 18 mA at 12V, up to around 22 mA at 14V. Anything more, and you risk 1) burning out the leds much faster, 2) cause the resistors to fail from dropping too much heat, and 3) Cause the Flexible Printed Copper that the led strip is made of to heat up p too much. With its high resistance per foot, you need to worry about burning it out or melting the glue.

24 Volts is guaranteed to burn out the leds though. Assuming 150 ohm resistors and a high 3.5 volt forward voltage drop, that's 13.5 volts on the resistor. Ohms law I = V / R so 13.5 / 150 = 0.09 Amps. That's 90 milli amps through leds rated for 20 milli amps. And that's P = V * I 13.5 * 0.09 = 1.2 Watts through resistors meant for 0.125 Watts or less. You'll burn out everything on the strip with 24 Volts.

The solution is simple. You should power the strip from 12 Volts but power correctly. Worst case, power it from the middle of your strip, at the 3.75 Meters mark. Best case, from the middle and both ends for the best brightness. Middle ground, power it at two points. 2.5 Meters and 5 Meter points.

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  • \$\begingroup\$ K thanks wasnt sure if DC was as simple as AC current. Ac you can put 110 to anything that uses 110, and bulbs etc only use what it draws. Seems DC if its 12 10 amp, is going to push 10 amp constant if it needs it or not. So next question is, what power supplies can handle this all time if need be. Ive been looking at regulated ps of course, but so many say avoid using prolonged hours. Also Im aware the 24v would be much stronger, thus 12 v 10 amp I thought would equal 24 volt 5 amp, but would create less heat with larger wires. Let me know if this follows key. \$\endgroup\$ – Billy Berry Jan 4 '16 at 1:27
  • \$\begingroup\$ Also I may can just run wires to the 2nd strip to reduce load on the first one, but would I just get a 12v 15a ps, run it, and it correctly push the power needed to each strip 10a to one 5amp to other? Guess is it self balancing from one power source \$\endgroup\$ – Billy Berry Jan 4 '16 at 1:43
  • \$\begingroup\$ Powering from both ends would be much simpler than at 2.5m and 5m, and the effect will be probably almost the same, especially since the manufacturer seems to guarantee good operation on 5m strips. \$\endgroup\$ – yo' Jan 4 '16 at 10:30
  • \$\begingroup\$ @BillyBerry You can connect multiple LED strips to one source, the only important thing is that the sum of the powers of the LED strips is not larger than the rating of the source. \$\endgroup\$ – yo' Jan 4 '16 at 10:31

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