Control of LED RGBW light with Tree dimmer

[Rob.no1]

Not specifically a loxone question, but kind of related... I am trying to control some Certikin PU2 RGBW lights (like these - https://pool-supplies.co.uk/certikin-mini-led-rgbw-light-push-fit-with-20m-5-core-cable---concrete-pools---pu2mlp-6215-p.asp) using a loxone RGBW dimmer tree, rather than their recommended wireless dimmers (https://pool-supplies.co.uk/certikin-pu2-rgbw-wi-fi-receiving-controller---one-required-per-rgbw-light-pu2mlrc-6216-p.asp). I have now tried two of these and on both occasions the red light seems to flash and then no longer work (all other colours work as I would expect), I am only using a small transformer (under what is required, just for test purposes) but am not running the lights at full brightness so wouldn't expect this to be a problem. 

Can anyone help identify if these should be compatible, and if they are, what could I be doing wrong to cause this issue? Is it possible I have blown the red LED?

I also notice that the recommended controllers say to use one per light, which I don't understand as they seem to have enough power to control multiple units, can anyone think of a reason for this?

Thanks

[Jonathan Dixon]

Afaik The loxone RGBW dimmer is 24V constant voltage, but the light you are using requires a 350mA constant *current* driver / dimmer, according to the datasheet:

https://genux.fluidra.com/get-sku-document/pu2lightinstructionmanual-213496--uid675428.pdf

So yes, you might have burnt out the LED, and need to use a different driver. I'm not sure loxone even make any constant current driver's? I use DMX ones. 

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[Rob.no1]

Thanks Joth, I thought I might have overlooked something like that - I guess I need to brush up on my LED knowledge. I don't suppose you can recommend any DMX dimmers that would be suitable?

[Jonathan Dixon]

I'm using these; https://www.aliexpress.com/item/4001200401126.html they work fine for my application, can't guarantee them with your lamps but the spec sheets seem to line up. 

(They are available as DIN rail mount too, which I wish I'd got instead, but haven't been bothered to swap them out yet. If you want inline ones I can sell you two :o)

btw this is why they call for 1 driver per LED: you can't wire constant current drivers in parallel.  You could theoretically put a couple in series, but will hit the 24V rail. The drivers I linked are actually compatible with 48V PSU so might support 2 or 2 of these in series, but it's a messy wiring plan.

Slightly odd the LED datasheet does not state the wattage of the emitter per channel. If it really did need 24V at 350mA suggests 8W, but 32W !  Your original link says 12W, so I guess that's a more reasonable 3W per channel, so only needs about 10V headroom, so yeah probably can drive 2 in series on a 24V PSU. YMMV!

HTH

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[Techdoctor]

You can get Constant Voltage to Constant Current converters. But might be a pain to implement though.

 Also one power supply (PU2MLPS) will do up to 26 lights, but each light needs its own controller, which to me makes sense. Since each light can then probably  be  controlled using the app I guess.

The way constant Current LEDs work is that they require normally 350mA current. And to make sure that is constant the voltage varies, up to a maximum of 24V in this case. I guess the controller provides the Constant current part as it has a 24V input. 

The Loxone LED controller is Constant Voltage, so the current varies, its also common Anode. Meaning there is only one +ve connection. This is probably the most common LED control system. I have installed bespoke LED lighting system in bars, restaurants, kitchens, games rooms and gardens etc.  

[Rob.no1]

Thanks for the link. I have ordered some of these to try... (I take it that the fact that the input voltage range is different on these vs the Certikin ones is not relevant as long as I still use a 24v Supply?) As I am only using four of the lights it seems wasteful to use their 350w Power supply, I was planning to use any standard 24v PS, will this be ok? I was thinking of swapping it for a 60w unit (based on the 12w per light plus 20%) or do they require something specific?

Rob

[Jonathan Dixon]

Judging by the pictures alone I very much doubt there's anything special about their power supply it looks like any one of the thousands available on AliExpress e.g.

https://m.aliexpress.com/item/32903868877.html

They're okay, available in many sizes, a bit noisy with fan but highly prone to overheating without the fan. Note they have exposed mains connectors, not UK compliant unless put in another case which helps with the noise but increases overheating risk!

The datasheet says their 320W PSU can drive 26 fixtures so needs no additional headroom at all.  going by that any PSU over 50W should be fine for four. I'd personally go to 24V 100W as that gives 4amps, and if they're 4 channels at 350mA they would need about 1A each with the drivers I linked.

(If you have a 12V PSU 50W to hand you may find they work just fine with that too, and run a bit more efficiently too. My suspicion is they only require 10V forward voltage)

Yes, those DMX drivers work fine with a range of input voltages. I run some at 24V and others at 48V

Joth

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[Rob.no1]

Thanks, that is what I thought. I will probably go with a din rail Power supply and dimmer and enclose in a cabinet. 

Sorry - another question, the Aliexpress seller has just come back and offered me an alternative which they say is the same (I guess they have changed design), but it doesn't have a common V+ connection, it looks like each colour has its own connection. Are these common (ie can I just connect my common V+ wire to one of these) or is this no good for what I need? link below shows the connections of the one offered:

https://www.aliexpress.com/item/4000176995170.html?spm=a2g0o.productlist.0.0.b6472b2020L9UK&algo_pvid=aea5c32b-4f61-446b-a68c-a4dd87b015a3&algo_exp_id=aea5c32b-4f61-446b-a68c-a4dd87b015a3-46

Regards

Rob

[Jonathan Dixon]

As yes the D4C din-mount is the one I wish I'd bought. My guess is the + connections are all commoned together inside, so you can use as many or few of them as you want (obviously ensuring at least one is connected to power the unit itself). 

That's just my guess! But on the inline ones I linked before (actually called a D4C-L), I don't power the LED from the dimmer at all: I  connect the LED anode directly to the PSU + output, and just route the cathode back via the dimmer. This keeps overall cable runs shorter and simpler inside my cabinet, means I can use a single "car" style fuse board to break out the power going to all LEDs from one place, and avoids needlessly routing the current via the PCB on the dimmer unit as that's just another weak point / potential cause of heating.

Good luck! Let me know how you get on with them?

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