Reliable 200w+ 12v supply for LEDs?

TheGiantHogweed

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Sep 11, 2015
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I'm back to being a little stuck again. Many of these supplies on ebay and amazon are just unbranded or some random name that you search, then find nothing.


I think I have luckily got away with getting cheap LED strips. The CRI is pretty poor, but they have worked out excellent value. They use what was stated as 2835 LED chips and have 2 wide and 120 of them per metre. They claim to use 24 watts per metre and I use 3 lots of 2.5 metre strips. The output of the power supply gets split then goes to each strip. It supposedly will use around 180w if there is no voltage drop. The light output suggests this is probably about right.



https://www.amazon.co.uk/gp/product/B07ZJ154DZ/

I started off with a power supply like this 12v 15a one but switched the lights off by a switch on the 12v output cable. This meant the supply was switched on permanently even when the lights were off (which was most of the time) This probably wasn't ideal. It then started making clicking noises and soon gave up after a year or so. I did rewire it and put the switch on the 230v input cable when I bought the replacement though. So it will now be totally off when the lights are off.

I then got the 30A version in the same link. This one has a fan which I didn't think would bother me, but it is tiny and doesn't seem to have a speed control depending on the temperature. The RPM rate must be insanely high and fixed. This was tolerable, but just a bit annoying. However, it has developed that at times when the fan isn't running, the supply emits a loud and high pitched noise (between 13 and 14khz). Many won't hear this but it is just unbearable for me. Guess it is my fault for going cheap, but I certainly can't trust these ones from amazon or ebay now despite seeming to have enough power in them.


Someone suggested mean well as being a good brand but I seemed to have difficulty in finding suitable supplies by them that are sold in the UK. I have however now found one:

https://www.powersuppliesonline.co....12-200-4w-12-16-7a-enclosed-power-supply.html

It looks incredibly similar to the dodgy ones I'd bought but is about 3 times the price. It does at least have a 3 years warranty and a well known brand name to it. And hopefully that will mean the parts inside will be reliable. I could do with a supply that has screw connectors like this one as the cables used have ring terminal connectors on them that I crimped into place.

If this supply is a good one, then let me know or suggest some others that similar and at around the same price point.


Thanks.
 

DIWdiver

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I would expect that Mean Well to be a significantly higher quality product than the Amazon one. I would not, however, expect the fan to be quieter. Oh wait, it doesn't have a fan!!

If pushing a PS near its limits for more than pretty short periods, I would provide it some additional cooling help by adding a small 12v fan to blow a little air on it. Even if you run it for half an hour a day, this could significantly improve its lifetime. On the other hand, if you operate it that little, its lifetime may exceed your needs!

If you don't want to add a little fan, at least make sure it has plenty of free air flow and isn't in a terribly warm space. You might consult the data sheet, but I suspect that mounting it on a vertical surface would improve air flow by convection vs mounting on a horizontal surface.
 

Lynx_Arc

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How about a Computer power supply? They can run for decades reliably although you have to probably do a little modding to make it work nothing too technical though.
 

TheGiantHogweed

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I would expect that Mean Well to be a significantly higher quality product than the Amazon one. I would not, however, expect the fan to be quieter. Oh wait, it doesn't have a fan!!

If pushing a PS near its limits for more than pretty short periods, I would provide it some additional cooling help by adding a small 12v fan to blow a little air on it. Even if you run it for half an hour a day, this could significantly improve its lifetime. On the other hand, if you operate it that little, its lifetime may exceed your needs!

If you don't want to add a little fan, at least make sure it has plenty of free air flow and isn't in a terribly warm space. You might consult the data sheet, but I suspect that mounting it on a vertical surface would improve air flow by convection vs mounting on a horizontal surface.

I've since found the page that sold the LED strips that I have: https://www.ebay.co.uk/itm/12V-24V-...144704?hash=item43f14cb400:g:AHEAAOSwtnpXlibf

I'm sure many on this forum would be against anything at this price, but you sometimes can get a real bargain. These are about the only cheap strips that don't appear to fade towards the end of the strip (presumably due to voltage drop) They are a bit on the

If my 3 strips of 2.5m use what the seller claims, then I will be using around 20 watts short of what this mean well power supply can handle.


It would be rather difficult for me to mount this flat but I may be able to find a way. My plan is to have it the same way I've had the others which is fixing it under a wooden beam in the garage. This doesn't look to have holes at each end so I may be able to use a screw at one end and a cable tie at the other. This then would be horizontal but I'm not quite sure if this is the way you meant when you mentioned this. With all the cables only just long enough and already having crimped wire ring terminals, it will be a bit tricky mounting it a different way. But regarding fans, I do have a lot of small PC fans that I can easily think of a way of fixing to the side and presume that as they are 12v they can simply run from the supply itself. CPU fans are really quiet so likely won't bother me and if they have any issues, at least I can sort that out without messing up the warranty!

The reason why I somehow thing fans would be quieter on proper branded products is because surely they would either be on permanently or have a variable speed. The one I got from amazon always came on at the same RPM. It must have been a tiny fan with an insanely high RPM as it sounded like quiet hair-dryer! Surely decent brands would have it regulated to spin faster when it gets hotter and not allow it to get hot enough for it to need such a noisy fan.
 

TheGiantHogweed

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How about a Computer power supply? They can run for decades reliably although you have to probably do a little modding to make it work nothing too technical though.


Yea I certainly did think about this. PC supplies are really reliable and their fans are very quiet. But they area too bulky for the planned location and as you say will need a bit of modding. I had one sometime ago before deciding to go for this amazon supply and I wasn't sure if an individual one of the multiple molex wires would cope with the load I intended to use.
 

archimedes

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How about a Computer power supply? They can run for decades reliably although you have to probably do a little modding to make it work nothing too technical though.

Perhaps I have simply had bad luck, but PC PSU are the components I have had fail more often than any other.

Doesn't seem to matter if I've spent more for "bronze, silver, gold, whatever" higher rated versions, either.

Obviously, it is a component which is heavily stressed ... either switched on and off frequently, or run constantly, and sees a lot of heat.

Next most common part to fail, seems to be graphics cards. Lots of heat there too.
 

TheGiantHogweed

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Perhaps I have simply had bad luck, but PC PSU are the components I have had fail more often than any other.

Doesn't seem to matter if I've spent more for "bronze, silver, gold, whatever" higher rated versions, either.

Obviously, it is a component which is heavily stressed ... either switched on and off frequently, or run constantly, and sees a lot of heat.

Next most common part to fail, seems to be graphics cards. Lots of heat there too.


Ah now that would be a problem. My switch would be on input cable (230v in the UK) input. So it would mean frequently turning the supply on an off drawing 180w instantly each time. I don't suppose that would be good for it. One reason why I think I would be better off going for the meanwell one I mentioned earlier.
 

Dave_H

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OK, so 7.5m of strip at 2A per metre requires 15A (180W). The 30A PSU derated to 50%, given proper
cooling (airflow) should work, but unknown if the high-frequency acoustic noise would be a problem
You might have to give it a try to find out.

I found a computer PSU rated 420W max. with 12v/18A output. Running at 15A might not be
enough derating, even though 180W is not close to the PSU's total power limit. Given their bulkiness
and possibly noisy fan, not the ideal solution. You might be able to split into two such PSUs, even
less good solution, but possible.

Another less good alternative is an iron-turkey linear supply such as used for two-way radio. Some
are rated up to 30A or more but typically 13.8v output which is a bit high for the strips, would cause them
to run brighter/hotter. Some may have adjustment to reduce to 12v or closer to it. And you might get
some line-frequency hum. They are bulky and heavy, but generally well constructed and conservatively
rated; might find some used/cheap as users switch to smaller/lighter switching PSUs.

On a sort of side topic, flex strip consumes 24W/m or approx. 7.3W per foot. I have a rigid LED strip about
a foot long using 84 SMT LEDs. Its design and distribution of heat is different but if run at slightly higher
power (46v /200mA = 9.2W) it gets mighty warm, arguably hot depending on ambient. Efficacy of newer
LEDs may be higher, but my strip requires constant-current drive, therefore no on-board resistors dissipating heat.
Flex strip looks like it will get hot, would affect lifetime of the LEDs; just throwing this in for consideration.

Dave
 

TheGiantHogweed

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Joined
Sep 11, 2015
Messages
35
OK, so 7.5m of strip at 2A per metre requires 15A (180W). The 30A PSU derated to 50%, given proper
cooling (airflow) should work, but unknown if the high-frequency acoustic noise would be a problem
You might have to give it a try to find out.

I found a computer PSU rated 420W max. with 12v/18A output. Running at 15A might not be
enough derating, even though 180W is not close to the PSU's total power limit. Given their bulkiness
and possibly noisy fan, not the ideal solution. You might be able to split into two such PSUs, even
less good solution, but possible.

Another less good alternative is an iron-turkey linear supply such as used for two-way radio. Some
are rated up to 30A or more but typically 13.8v output which is a bit high for the strips, would cause them
to run brighter/hotter. Some may have adjustment to reduce to 12v or closer to it. And you might get
some line-frequency hum. They are bulky and heavy, but generally well constructed and conservatively
rated; might find some used/cheap as users switch to smaller/lighter switching PSUs.

On a sort of side topic, flex strip consumes 24W/m or approx. 7.3W per foot. I have a rigid LED strip about
a foot long using 84 SMT LEDs. Its design and distribution of heat is different but if run at slightly higher
power (46v /200mA = 9.2W) it gets mighty warm, arguably hot depending on ambient. Efficacy of newer
LEDs may be higher, but my strip requires constant-current drive, therefore no on-board resistors dissipating heat.
Flex strip looks like it will get hot, would affect lifetime of the LEDs; just throwing this in for consideration.

Dave



Well I've ended up buying the MEAN WELL RSP-200-12 supply. Including VAT, it is around 3 times the price of the other supplies I've had that have had some fault within 2 years or less so I hope this will last longer! At least it comes with a 3 year warranty. I happened to have a spare PC power supply fan (around 120mm). While it isn't especially quiet, i've also got a noctua low noise adapter that came with my CPU fan that I didn't use. So I used this to slow and make the fan quieter. I still have the fan mounted in the steel frame it came in and just have the 12v supply mounted in it on a beam in my garage with the fan connected to the output.

It not only gets ever so slightly warm even when it has been on for 30 minutes.


My LED strips only seem warm to the touch, but you can't touch them direct as they are in loose silicone tubes which may help with the heat. But with expensive LED's that I've used, even when mounted on an aluminium board then with some thermal paste and a large heat sink, the whole lot still seems to get about as hot as a radiator. Note this is 12 strips of 12 LEDs mounted very close on the panel. That uses around 30 watts and hasn't faded or started to change colour so I think they will last.

My garage strips do give out a lot more light than this due to the amount of LEDs, but they do feel slightly cooler at each end of the 3 strips. While they don't look dimmer there, I now feel it is quite possible there is some voltage drop over the length of these, though very little. The cable I use is rated at 12v 16A, and I have a single cable coming from the output of the supply to a junction box that splits to the 3 strips. When the lights have been on for some time, the single 12v cable actually feels ever so slightly warm, which does suggest it it using close to it's rating of 16A.

Until recently, I always wondered why 12v cable is often so thick and yet can't handle anything like the current of 230v cable until I read that it is often copper clad aluminium or something similar. The 12v cable I'm using is even thicker than british 1.5mm cable which can handle up to 15A at 230v. While as I said, my 12v cable is rated at 16A 12V which given the slight heat in it for my application does seem the correct limit, although I do wonder how different the properties are between the cables are.



I have one very cheap flexible strip in the attic at the full 5m length. This one shows an obvious sign where voltage drop is a problem. The advertisement is correct that it uses 12w per metre - but only if you wire it every metre. Supposedly, it should use 60w so that is the supply I thought I would need to use (12v 5A), but testing the power of it, it is only 22w with one end being a fair bit brighter than the other (as well as much warmer) Over time, one end where it is powered is now very yellow while the far end is fine.

As I explained earlier, I think I've been really lucky with the 3 2.5m strips I have in the garage. They were not expensive, but are very bright and look totally even colour and brightness wise despite having been installed for several years now. I think I've just learned that it is more important not to go cheap with the power supply - for high loads at least.
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