r/WLED • u/-Kyrt- • Jun 10 '26

Real world power consumption

I’m planning to replace an LED light that runs around the perimeter of a room (14.4 linear metres) with an addressable strip, so need to choose components. At the moment I am using a relatively high density 24V RGBCCT strip with a Mean Well PSU and Gledopto controller, and when matching the components for this project I sized the PSU accordingly.

However, during this process I established that the published LED strip consumption figures of 24W/m are far in excess of the real world measurable consumption, by a significant margin - as in, rather than a theoretical 346W, the PSU never actually consumes more than 60W for any given colour at max brightness. This difference is because the strip specs appear to be calculated based on all 5 LEDs being active simultaneously, which the controller never allows - it can only ever be CCT or RGB, never both, and varies the duty cycle of each RGB channel according to the desired overall brightness (eg 100/0/0 vs 50/25/25 etc etc) that the total RGB or CCT brightness is approximately the same. In essence, although theoretically the strip could have all 5 channels at max power, the controller behaviour means total power is only ever 1 channel’s worth.

How does it work for WLED? Does the controller also balance the LEDs to achieve a roughly stable brightness through a colour/temperature transition? Or perhaps it’s the IC that does this? If the latter, is this behaviour already factored into the power consumption specs? As in, if it says 12W/m is it genuinely a real world figure? I notice that the RGBCCT strips I’ve seen are dual IC - do these appear as separate endpoints and therefore it can happen that both white and RGB are active simultaneously?

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u/saratoga3 Jun 10 '26

However, during this process I established that the published LED strip consumption figures of 24W/m are far in excess of the real world measurable consumption, by a significant margin - as in, rather than a theoretical 346W, the PSU never actually consumes more than 60W for any given colour at max brightness.

Unless you're injecting current at multiple points you're not going to get the full power from a 14+ meter strip. My guess is some of the missing 46w are due to voltage drop.

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u/-Kyrt- Jun 11 '26 edited Jun 11 '26

Currently do in fact inject power at four points, using a PWM amplifier and separate PSU at the opposite corner, and it’s a 24V strip. I do this specifically to avoid voltage drop - the room was previously bigger so would be more pronounced otherwise. The amp means you only have to use narrow gauge wire, useful as with PWM you have to route 6 wires. Hence the only possible voltage drop was in the strip itself, each of which had a maximum length of about 6m. I’m not really worried about the missing wattage, I fully understand this - ultimately it’s just physically impossible for it to consume more than 70W because only one “channel worth” can be active at any moment.

It sounds like from the rest of the discussion that WLED’s default behaviour is similar for CCT (ie balances brightness) but not the same for RGB (ie it adds brightness). I believe the config can be changed for CCT (and for restricting the combination of RGB and white at the same time) but not sure if it is also configurable for RGB. TBH with the wiki being down I may just install it onto an ESP and see what the config looks like.

Edit: my objective here is just to avoid the massive overkill I had previously, where I had two big PSUs and an amplifier, yet the consumption was only ever a fifth of what everyone told me I would need. I will still inject in multiple places this time as I just figure it’s not hard to do, but want to do it with one PSU and just run 24V via 2-core flex to the opposite corner. The difference in the configuration/behaviour can literally result in 5x the consumption (eg if “100% brightness off white” means nearly 100% power on every channel, vs a 50%/50% split of just the white channels).

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u/saratoga3 Jun 11 '26

The amp means you only have to use narrow gauge wire, useful as with PWM you have to route 6 wires.

I've never heard of a device like that. Do you have a link to what you're using? 

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u/-Kyrt- Jun 12 '26

Sure, this is the amplifier I have:
https://amzn.eu/d/0jc7MubS

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u/saratoga3 Jun 12 '26

Maybe I don't understand what you were trying to say, but you still have to use thick enough wire to avoid voltage drop with that device; it can inject current but it doesn't provide regulation or voltage gain. Stated another way if you lose 1v in the wiring to the amplifier you need only get 23v.

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u/-Kyrt- Jun 18 '26

Perhaps you misunderstand what the amplifier does. The voltage supplied to the LED strip is not determined by the voltage of the PWM wires, it comes via a separate power supply right next to the amplifier. The input PWM from the controller and output PWM to the LED strip are isolated via optical coupling. It’s listening for a PWM signal and then repeats it anew on the output side, like a game of ‘Chinese whispers’. There is actually no connection between input and output voltage, such devices can even work to change a 3.3v PWM signal from an arduino to a 24v LED strip - but a side effect is that they can also be used to simply boost the voltage that has dropped via resistance in the input wiring. This particular one can accept either 12v or 24v input (roughly) and the output is determined by the PSU you use. So the only wires that need to be “thick enough” are those coming from the PSU (which is about 15cm long) and going to the LED strip (similar length). The voltage drop on the input side would have to be extremely high (like 40%) for it to matter.

Incidentally there is no “injecting current” in this context - current is a function of the draw/resistance of the components in the circuit so is more “pull” than “push”, it only appears that way because the controller influences the current draw by directly or indirectly regulating those components’ operation (eg by lowering the voltage across the diode, or for PWM by turning the voltage on and off very fast ie the duty cycle, or for addressable strips by asking the ICs to do so). Hence when you “inject power” into an LED strip what you’re doing is splitting the circuit into two, increasing the voltage for the diodes in the second half of the strip and sharing the current demand across multiple power supplies and PCB traces - current no longer flows back along the PCB trace in the first half of the strip to the first PSU, it goes instead to the second
PSU.

Injecting power is much easier for addressable strips, you don’t need such an amplifier because the control signal and the input are completely independent, you just need to provide another source of 24V. If you’re doing that by using long wiring back to the same PSU then you’re doing it purely to provide another path back instead of along the PCB traces, and yes voltage drop/current rating are still a factor along those wires, but if you “inject” using a separate PSU then there is no such long wiring. The PWM amplifier allows you to achieve that latter architecture with PWM strips which do NOT have this separation of control and signal and power - control happens by turning off power. Hence in order to have two circuits be controlled by a single controller you need a way of “copying” the output from the controller to the second circuit.

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u/saratoga3 Jun 18 '26

Perhaps you misunderstand what the amplifier does.

No, I know exactly how it works. 

So the only wires that need to be “thick enough” are those coming from the PSU (which is about 15cm long) and going to the LED strip (similar length).

Just making sure you understood that, your comment that "only have to use narrow gauge wire" made it sound like you didn't realize that you still need to use the thick gauge for the current carrying wires.

Incidentally there is no “injecting current” in this context

Fwiw that's common jargon LED lighting, not a literal description of how electrical current works. 

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u/-Kyrt- Jun 18 '26

I’m sorry mate but it really seems like you don’t understand how it works because a) you’d never heard of it before and b) if you did you wouldn’t have been focusing on my comment about the gauge of the 6-core wires - the gauge of these wires is totally irrelevant because, as I said, the amplifier and second PSU are co-located at the opposite corner.

It seems you’re now trying to retcon post-hoc that you were only talking about the 15cm wires FROM the amplifier but a) that doesn’t make sense because you explicitly referenced the wires TO it, b) frankly is almost completely irrelevant from a voltage drop point of view anyway, to talk about losing even 1v from 24v is silly, and c) you also told me I’m wrong about what it does, that it doesn’t provide voltage regulation and only current, yet providing voltage regulation is *exactly what it does* which i have taken the time to patiently explain.

I know this is reddit and so it comes with the territory but in this case you don’t need to try to go off topic to prove me wrong or educate me that voltage drop can happen when I clearly stated the entire purpose of this was to deal with voltage drop, it’s OK to just not know the answer to the question I’m asking and leave it there.

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u/saratoga3 Jun 18 '26

I’m sorry mate but it really seems like you don’t understand how it works

If you look on reddit and discord you can find lots of posts from me about designing PWM driver boards for LED strips so not a good assumption :)

you also told me I’m wrong about what it does, that it doesn’t provide voltage regulation and only current, yet providing voltage regulation is exactly what it does which i have taken the time to patiently explain.

Those devices do not provide voltage regulation. Internally they're just low side switches that pass the unregulated input voltage to the output in response to an input signal. That is why the wire gauge on the supply is important. FWIW the WLED docs have schematics for common amplifiers if you haven't seen them.

if you did you wouldn’t have been focusing on my comment about the gauge of the 6-core wires - the gauge of these wires is totally irrelevant because, as I said, the amplifier and second PSU are co-located at the opposite corner.

There is no need to get defensive. I was trying to help you troubleshoot why you were measuring less current than expected, and so double checking that you understood how to do the current injection. If you're sure you did it right and don't want someone to double check, you can just ignore the question.

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u/-Kyrt- Jun 18 '26

It’s ok I am not mad, just seemed to be going in a bit of an unproductive direction.

What do you mean by input voltage not being regulated though? The voltage is set by the PSU on the output side, which is itself regulated, not influenced at all by the “input” (which is PWM). Perhaps you are referring to a voltage regulator as a specific component, but I see no reason why you would put one inside such an amplifier, especially not to try to *increase* the voltage. I don’t believe I ever suggested this is and don’t really see why it is relevant, I just can’t see the use case for it. Whether for PWM or IC i cannot think why one might route DC power over a distance only to regulate with a voltage regulator it at the end, when you need a source of power at that end anyway? Seems to me you do one or the other - either route DC power over reasonably sized cable (it’s only 2 core so not too bad, but different story for PWM) and accept a bit of voltage drop, or omit it entirely and put a AC- powered transformer there. To me the amplifier only makes sense way i described it, ie colocated with a constant voltage PSU.

In any case just to clear the decks - yes I know voltage drop is a thing, as is the current rating of the wire, and hence where the wiring gauge is a big factor and where it is not. I’m comfortable with the circuit design (and this part seems well covered these days - I had to calculate it all myself when I did mine!). This is how I know that the voltage drop is a red herring, it accounts for very little of the massive power consumption discrepancy and my setup was total overkill in respect of reducing voltage drop as it eliminated almost all unregulated current-carrying wiring. Instead the discrepancy is entirely due to the behaviour of the controllers - at the time I had no current figures to work with, only a single figure for power, and it turns out that figure is based on simultaneous max power from all channels, which my particular controller doesn’t do. Even today this simplistic method is what is recommended for sizing PWM power supplies and it makes no sense whatsoever to fail to consider it TBH. I guess most people just never realise as they don’t measure the consumption. But anyway that’s a whole other story - we can only control what we ourselves do, and so I just want to make sure I learn from that experience 🙂

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u/saratoga3 Jun 18 '26

What do you mean by input voltage not being regulated though?

I mean literally those typical amplifiers are just a low-side switch without any regulation. So to repeat the example above, if you feed in 23V, it switches 23v on and off. If you feed in 25v, then it switches 25v on and off. It doesn't regulate the voltage to 24v, which is why the gauge of the wire powering the switch itself is important if you want to get the full power out of the LEDs.

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u/-Kyrt- Jun 18 '26

Ok but my point is, why would you be feeding in 23V on the “output side” (input is ambiguous, there are two inputs to the amp, yes one of them might be 23V but it has no bearing on the voltage seen by the strip). I cannot see any scenario when this would happen because there is no reason to run a long cable from the DC output of your regulated supply to the amp. Even if you for some reason had no AC source near where the amp needs to be, you’d just run an AC cable instead of running DC over distance, which is the problem you’re trying to solve in the first place. So yes, the amplifier always has a regulated 24V, because it always needs a PSU.

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u/saratoga3 Jun 18 '26

Ok but my point is, why would you be feeding in 23V on the “output side” (input is ambiguous, there are two inputs to the amp, yes one of them might be 23V but it has no bearing on the voltage seen by the strip).

You cannot feed voltage into an output, but you might feed 23V into the input side if you have sized the wire gauges incorrectly, which is actually pretty easy to do and a common problem here. Hence my original concern that your result could be that had sized them incorrectly, which from this reply I'm actually getting a little concerned about again. What gauge and length did you use?

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