LED Dimming - General dimming of LED work light - Mosfet dimmer + Navigator

General Discussion
1

Hi,
I’m using a Blue Robotics Navigator and want to dim a standard off-the-shelf 24 V / ~150 W automotive LED light bar via joystick control.

It’s clear that this cannot be done directly from the Navigator outputs. An external interface between Navigator and the light bar is required.

What I’m looking for is the simplest proven approach, preferably off-the-shelf hardware.

A few focused questions:

  1. Has anyone successfully dimmed a standard automotive/work LED light bar in practice?

  2. What type of interface worked reliably?

    • Servo-PWM → duty-cycle PWM converter + MOSFET

    • Ready-made MOSFET dimmer module

    • Other driver boards that accept low-voltage control input

  3. Does PWM on the supply side of typical automotive LED bars behave well, or do internal drivers cause flicker/reset/noise issues?

  4. Are there any specific modules or parts people can recommend for a 24 V / ~150 W load?

The goal is robust joystick-controlled dimming in an ROV environment, not custom LED electronics.

Any real-world experience is appreciated.

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2

Hi @SDI,

I’m not experienced with automotive light bars, so will avoid commenting on that component of the discussion.

It’s worth noting that the Navigator’s PWM driver chip is actually an LED driver. Assuming your light bar is ok with the same PWM frequency as the ESCs are using (e.g. up to ~400 Hz, using the RC_SPEED parameter) then you can just set the relevant SERVOn_MIN and SERVOn_MAX parameters for your output to achieve the duty cycle you want, which you can then feed to your MOSFET. A dedicated duty-cycle PWM converter is likely not necessary (unless you require higher frequencies than the other connected electronics can handle).

You could control that with ArduSub’s built in lights joystick button functions, or alternatives like an on-screen slider in Cockpit.

3

Thanks for the link, Elliot — that’s helpful documentation for setting up the PWM control and the Cockpit slider on the Navigator side.

What I’m still trying to understand, though, is the behavior on the load side. The guide explains very well how the PWM signal is generated and routed, but it doesn’t really address how a typical off-the-shelf automotive/work LED light bar behaves when its input power is PWM-controlled via an external MOSFET.

I’m mainly interested in real-world experience here: whether this approach works cleanly with such lights, or whether people have seen issues like flicker, instability, resets, noise, minimum duty-cycle limits — or cases where it simply didn’t work or went up in a smelly cloud of smoke :slight_smile: