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I am looking for a solution to individually dim (or if not possible switch) 30 Cree XR-E LEDs driven by a 18v 4.0Ah Makita battery and a step-down converter to go from 18v to 3,5v capable of handling about 120watts (total power when all LEDs are lit).

I'm thinking of using a Raspberry Pi 3, combined with a FadeCandy controller and a set of WS2811 drivers. Would this work? And how can I use the WS2811 chips to control high-power LEDs?

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  • \$\begingroup\$ Draw a circuit diagram. \$\endgroup\$ – winny Feb 28 '18 at 11:19
  • \$\begingroup\$ What are the drive capabilities of the WS2811? Do you really think they are suitable for even 2 seconds of consideration? \$\endgroup\$ – Andy aka Feb 28 '18 at 11:24
  • \$\begingroup\$ 4.0mAh isn't going to power anything for long. I'm guessing it's actually 4.0Ah? \$\endgroup\$ – Finbarr Feb 28 '18 at 13:21
  • \$\begingroup\$ Thanks for your answers. I'm relative new to this world. I will try to draw one but never did, so will take me some time I guess.. It is 4.0Ah indeed.. Basically I have a Raspberry Pie, an 18v power supply, and 30 leds which I want to control to create something like this: bertspaan.nl/led-wheel \$\endgroup\$ – Jasper van den Boezem Feb 28 '18 at 13:40
  • \$\begingroup\$ You do realize that with that battery it will work for 20 minutes (ignoring various losses)? \$\endgroup\$ – Jan Dorniak Feb 28 '18 at 19:17
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18v 4.0mAh Makita battery

Are you sure it's not 4000 mAh?

how can I use the WS2811 chips to control high-power LEDs?

The WS2811 will limit you to 18.5 mA. It will light up the XR-E fairly bright but nowhere near their 700-1000mA max.

If you want to use max power of these LEDs then you would need to use the outputs of the WS2811 as the PWM input signal to an LED driver circuit by using a resistor rather than an LED connected to the outputs.

The Texas Instruments TLC5973 3-Channel, 12-Bit, PWM Constant-Current LED Driver with Single-Wire Interface would be a much better choice than the WS2811.

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