12 Volt dimming control for a trailer

We have a trailer with (LV) lighting that has it's wiring run to a single location. I thought that I could use Fibaro RGBW controller to accomplish dimming but after comparing schematics it appears that it will not work. The trailer dims on the hot side and all bulbs use the chassis for ground. The Fibaro uses the ground leg for dimming so I'm back to square one. Any pointers to get me going?

Apparently, the Sylvania 72569 has been discontinued but I'd bet that the Zibgee power module on the new model is worth a gamble that it is the same. I've tested it on 12vdc but currently run it & led fairy lights on usb. Works/dims with HE.

I can think of two possibilities:

  1. Power the Fibaro RGBW from its own adapter (isolated from the RV system).
    Connect the C of the Fibaro (which is also the common for the adapter) to the positive of your LV lighting system.
    Connect any one of the R, G, ,B or W contacts to the LV lights.

In this mode the Fibaro is operating as a floating switch and should work fine as long as the LV lighting does not exceed the Fibaro load capability.

  1. If you are willing to solder a few wires (3 wires) a simple P Channel Mosfet will do the job of converting between the Fibaro and the LV system. If interested I can suggest parts and how to wire.


John thanks for helping. The mosfets will allow higher loads correct? I can measure the current loads but believe that they will be about 6 amps per circuit.
On the wiring would I be restricted to using a single channel? If I can use them all then than it sounds like a very workable plan.


Yes a MosFet will allow much higher currents. And you can easily parallel mosfets to get more current. I can see an easy 20 amps with a single mosfet (you may need a small heatsink for such a current).

I would be uncomfortable suggesting using more than one channel of the Fibaro to increase the current capability. Reason is that if only one channel came on (software, delays etc) you would overload it and perhaps damage it.

Personally I think the mosfet would be the best solution. However I'm comfortable working with individual components. One clear benefit, if something goes wrong you've damaged a $2 mosfet not a $70 Fibaro.


We have a minimum of 20 circuits to due 15 are dimmable so using the Fibaro for 1 channel won't cut it.

If the 6A / circuit is approx true you are talking about 90 amps dimmable and another 25 - 30 A non dimmable.

I can see no other way than Mosfets unless you only want ON/Off in which case you can use a / some relays.

Like I said, I can help you layout the MosFets if you want to go that way.

I have some additional information that I thought I'd pass on.
These are the current circuits on the board :
7 circuits are 5 amps non dimming
8 circuits 2 amp dimmable
2 circuits 2 amp non dimming

Some other notes Dimming is 0 - 12 volts measured at the board outputs. There are a group of inputs that are not used that I don't understand but might provide a way to interface to the circuits. They are marked + and -?

Thanks Again

Ok so what it seems you have is a power controller of some sort. I've not had occasion to work with any of this type of unit. So I can/won't make connections suggestion.

I would call the mfg and see what inputs / controls might be available to do what you want. If they are able to suggest an approach I'll do my best to help you.

The board is being controlled through can buss. Still trying to find out if the inputs are analog or digital and if they are usable.

CAN bus wow I would not have thought that. So this must be a motor home. I would guess the CAN bus could be used to control the lighting however it would not be a low tech project. You are better following your current path.


Its a trailer. One thought I had was employing a WiFi to can bus adapter. Can Hubitat sent commands via TCP?

Your out of my comfort zone here. I've worked on vehicle CAN bus but never looked into wireless interfaces to the CAN bus although I can see no reason a wireless interface wouldn't work.