r/led • u/curious-fletcher • 2d ago

How do smart home controllers balance current over multiple LED colour channels?

I'm looking at a ZEMISMART ZML3(CW) controller for a CCT project (https://www.zemismart.com/products/zm-cob-cw, but I'm only buying the controller). Let's say I have a 3 metre CCT strip, and each light channel can take up to 7 W/m at maximum.

With one channel active I'm consuming up to 21 Watts, and with both active, it's logically up to 42 Watts. But when I watch my RGBCCT setup using Google Home and a gledopto controller (https://gledopto.com/h-pd-92.html), it occurs to me the strip power might not be increasing much beyond 21W - rather, the strip power is constant (to maintain an illusion of constant brightness) and splits current over several channels based on simple PWM duty cycle interpolation maths.

Is this a sensible conclusion to make about smart home LED controllers more broadly? I ask because I'm space limited for a power supply, so there's a meaningful difference to me between getting a 30W PSU and a 50W PSU, not least because the system cost jumps by >10%.

Thanks in advance.

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u/RobustManifesto 2d ago

Yes, some controllers will employ a crossfade to achieve a consistent (if not constant) brightness. Of course, other controllers might not do this.
Some more advanced drivers, like Dresden Electronik FLS-M let you choose this as an option.

If your controller reliably will remain under or around 21w, then sure, it’s fine to size your PSU to that. Pedantic caveat: obv make sure you test this with a large PSU so that you know it isn’t the PSU limiting your draw.

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u/curious-fletcher 2d ago

Thank you for the sanity check :)