Hi, I would like to make an underwater light powered by a 12 V power source on land and a 20 m submerged cable. In order to dim the lights, is it possible to use a Thruster Commander in an enclosure and connect the lights to it? The Lumen Lights are stated to be 15 W. Is that the max power of each light or for the pair combined? I appreciate any insights you can share.
Hi @Algetun,
You may wish to look at our https://bluerobotics.com/learn/voltage-drop-calculator/?gauge=22%20AWG&conductors=1&voltage=12%20V&length=20%20m&input=2.5A, to determine the electrical losses from a power supply that’s 20m away - they’re quite significant if you’re for example planning to use lumen cable the full distance.
This should be possible yes, as the thruster commander output provides the correct kind of PWM signal. For easiest setup I’d recommend connecting your potentiometer to the ‘SPEED’ input, since it can be used as a single input without any others needing to be connected 
You can extend the potentiometer wires without too much concern as they carry minimal current. The worst case scenario would be not being able to turn the lights completely on or off, but even 20m of 28 AWG wire (think unusually thin jumper wires or ethernet cable) should only be a few ohms, which is negligible when compared to the 10k potentiometer
The Peak Current in the Lumen technical details is 15/V_{in}\ Amps, so a single Lumen is max 15W, and a daisy chained setup of N Lumens would use N\times 15W. That’s also useful for the power efficiency requirements/voltage drop calculations of the power cable, especially if you require the maximum possible brightness of the lights (which is only possible for supply voltages >=10V).