I just switched my old tube florescent lights out with dim-able LED strips. I bought a DC dimmer wall switch for the lights but it had 4 wires and there was no way to install into my 2 wire system. I can find nothing on the internet. Has anybody put a dimmer switch in a 2 wire RV system?

There are a bunch of them on eBay. Just search for RV led dimmer.

ScottG wrote:There are a bunch of them on eBay. Just search for RV led dimmer.2 Wires?Not so sure about that unless they are nothing more than a variable resistor.DC electronics will need at least THREE WIRES in order to work.Input + from batteryBattery "ground" (-)Output + (variable 12V DC) to lightsSince OP has only 2 wires to work with they will most likely have to run a battery "ground" (-) to the switch location.I suspect that the OPs wiring is only Battery + and the switched + that returns to the light fixture and no battery (-) to be had...

Just google "12vdc led dimmer". Dozens available, Amazon, eBay, etc.As Gdetrailer says, OP will likely need to run a ground wire to the switch location.

Gdetrailer wrote:ScottG wrote:There are a bunch of them on eBay. Just search for RV led dimmer.2 Wires?Not so sure about that unless they are nothing more than a variable resistor.DC electronics will need at least THREE WIRES in order to work.Input + from batteryBattery "ground" (-)Output + (variable 12V DC) to lightsSince OP has only 2 wires to work with they will most likely have to run a battery "ground" (-) to the switch location.I suspect that the OPs wiring is only Battery + and the switched + that returns to the light fixture and no battery (-) to be had...They're not just pots and they don't need three wires if they have full 12v coming in because they use that to power an appropriate circuit.Here are examples:Simple surface mount Wall mount led dimmerI have both of these.

ScottG wrote:Gdetrailer wrote:ScottG wrote:There are a bunch of them on eBay. Just search for RV led dimmer.2 Wires?Not so sure about that unless they are nothing more than a variable resistor.DC electronics will need at least THREE WIRES in order to work.Input + from batteryBattery "ground" (-)Output + (variable 12V DC) to lightsSince OP has only 2 wires to work with they will most likely have to run a battery "ground" (-) to the switch location.I suspect that the OPs wiring is only Battery + and the switched + that returns to the light fixture and no battery (-) to be had...They're not just pots and they don't need three wires if they have full 12v coming in because they use that to power an appropriate circuit.Here are examples:Simple surface mount Wall mount led dimmerI have both of these.OP said they only have TWO wires.That means they do not have 12V NEGATIVE GROUND where their switch is.The item you selected NEEDS the 12V NEGATIVE GROUND in order to work.Please note, the two terminals marked (V-) in the picture from your link. Those ARE for the 12V NEGATIVE GROUND CONNECTION.That device WILL NOT WORK without a connection from the 12V NEGATIVE GROUND.The OP WILL have to run a separate 12V NEGATIVE GROUND to make that or any other dimmer work.This can be tricky to impossible in a typical trailer wall to fish wires.

Dimmer wall switch for interior LED lights? | Good Sam Community

tommymsw
Explorer
Feb 27, 2018
I GOT IT TO WORK!

I just used the power in and out to the 2 wires that were at the switch. Then I just tied BOTH grounds to a ground wire running near the switch. Seems to work fine so far! I will check it for heat and such although the LED strip is pulling so little power, I am not overly concerned.

Thank you for all who helped. I would have given ip and returned it without the help.
Gdetrailer
Explorer III
Feb 27, 2018
tommymsw wrote:
AH HA!!! So....

I DO see some DC wires running a few feet under the light switch (going to the LP sensor). If I wire into THAT ground wire, should it work? Or do I need the EXACT ground wire that runs to the lights?

And I have 2 wires for (ground) on the switch. Should I put them BOTH to the ground? Or only one? and what one? IN or OUT? :)

The wrinkle to that plan maybe as DrewE pointed out..

Some of those dimmers actually pass the pos lead at full voltage and reduce the ground lead (IE "lift" the ground potential).

That type of dimmer using only one ground lead will not work and you would need to have 4 leads, two from the battery pos and neg plus two going to the light pos and neg.

Won't know which one you have until you try it.
tommymsw
Explorer
Feb 27, 2018
AH HA!!! So....

I DO see some DC wires running a few feet under the light switch (going to the LP sensor). If I wire into THAT ground wire, should it work? Or do I need the EXACT ground wire that runs to the lights?

And I have 2 wires for (ground) on the switch. Should I put them BOTH to the ground? Or only one? and what one? IN or OUT? :)
westend
Explorer
Feb 27, 2018
Otherwise if you wanted to dim slightly it is possible to add a resistor in series but you will need to know how much voltage the resistor will drop and how much current will be flowing through the resistor

led power calculator

series or parallel arrays
tommymsw
Explorer
Feb 27, 2018
Gdetrailer wrote:
tommymsw wrote:
So I have LITTLE chance of running a new wire. I have a class A Winnebago and all the wires I see seem to have been run in the walls and then had foam sprayed into the walls. It is REALLY nice for sound and insulation, but not so nice for running new wires!

The LED light I put in are "strip lights". They work GREAT and are dimmable. But looks like I am stuck just using them normal. It is a bummer that they don't have anything with a few (resistors?) in them to lower the voltage. Even if there were just a few levels... Like 3v, 6v, 9v, 12v.

Can you mount the dimmers in the light fixtures?

Might be a bit inconvenient to do so but this way you can dim then when full brightness is not needed and turn them up to daylight levels when needed..

Leave regular switch in place and it will turn the light on/off.

Otherwise if you wanted to dim slightly it is possible to add a resistor in series but you will need to know how much voltage the resistor will drop and how much current will be flowing through the resistor to make sure you use a resistor wattage high enough for the heat dissipated..

If you do the resistor route, don't tell, the anti resistor police on the forum will be whining about all the energy you are wasting and will beat you over the head about it until you change your mind :E

I came here now because I had that EXACT thought. The lights themselves DO have a hot and a ground!

So MAYBE the ground wire runs near where the switch is and I can grab it there (I will have to look at the wiring documentation).

Otherwise... It think you are correct... I should be able to put a dimmer ON the light (or right next to it) although that will be a little weird? I think it will look OK. The dimmer I have is just a small, dark brown box that you touch to dim. Shouldn't look that bad on the ceiling.

Not ideal? But workable. :)
Gdetrailer
Explorer III
Feb 27, 2018
tommymsw wrote:
So I have LITTLE chance of running a new wire. I have a class A Winnebago and all the wires I see seem to have been run in the walls and then had foam sprayed into the walls. It is REALLY nice for sound and insulation, but not so nice for running new wires!

The LED light I put in are "strip lights". They work GREAT and are dimmable. But looks like I am stuck just using them normal. It is a bummer that they don't have anything with a few (resistors?) in them to lower the voltage. Even if there were just a few levels... Like 3v, 6v, 9v, 12v.

Can you mount the dimmers in the light fixtures?

Might be a bit inconvenient to do so but this way you can dim then when full brightness is not needed and turn them up to daylight levels when needed..

Leave regular switch in place and it will turn the light on/off.

Otherwise if you wanted to dim slightly it is possible to add a resistor in series but you will need to know how much voltage the resistor will drop and how much current will be flowing through the resistor to make sure you use a resistor wattage high enough for the heat dissipated..

If you do the resistor route, don't tell, the anti resistor police on the forum will be whining about all the energy you are wasting and will beat you over the head about it until you change your mind :E
DrewE
Explorer II
Feb 27, 2018
tommymsw wrote:
So I have LITTLE chance of running a new wire. I have a class A Winnebago and all the wires I see seem to have been run in the walls and then had foam sprayed into the walls. It is REALLY nice for sound and insulation, but not so nice for running new wires!

The LED light I put in are "strip lights". They work GREAT and are dimmable. But looks like I am stuck just using them normal. It is a bummer that they don't have anything with a few (resistors?) in them to lower the voltage. Even if there were just a few levels... Like 3v, 6v, 9v, 12v.

How are the LED strips wired up--specifically, what do they use for current limiting/control? If it's series resistors, you could put appropriate resistances in series with your switch to drop the power and get dimming. If it's an active regulator of some sort, on the other hand, that probably won't work very well as the regulator will compensate..at least until it can't, and the light may just shut down at that point.

LEDs are somewhat peculiar (at least when compared with incandescent bulbs) in that they are decidedly not ohmic in their response. The voltage drop across a lit LED is very nearly constant, regardless of how much light it is producing. The light produced, and power dissipated, is proportional to the current flowing through it. This implies that there needs to be something limiting and controlling this current.

Note that quite a few of the 12V LED dimmers available are "low side" dimmers and work by switching the ground connection while passing the +12V power through. This means that you need the ground wire from the fixture to install the dimmer. If that's impossible, you need to find a "high side" dimmer that switches the +12V power rather than the ground.
tommymsw
Explorer
Feb 27, 2018
So I have LITTLE chance of running a new wire. I have a class A Winnebago and all the wires I see seem to have been run in the walls and then had foam sprayed into the walls. It is REALLY nice for sound and insulation, but not so nice for running new wires!

The LED light I put in are "strip lights". They work GREAT and are dimmable. But looks like I am stuck just using them normal. It is a bummer that they don't have anything with a few (resistors?) in them to lower the voltage. Even if there were just a few levels... Like 3v, 6v, 9v, 12v.
wa8yxm
Explorer III
Feb 27, 2018
The four wires on teh dimmer are HOT/Ground in and HOT/Ground out.

You should have a 2nd wire likely beind the switch which is the Ground wire up to the Fixtures. they do not (Generally) run hot and ground via different paths. all you need to do is find it.

Side note: PWM dimmers can cause Radio/Television interference.
dougrainer
Nomad
Feb 27, 2018
A LOT of so called 12 volt dimmer switches will NOT work with RV 12 volt LED lights. They either will NOT work at all or they will cause the LED to pulsate. The usual factor I see, is the COST is what determines what will work correctly. Remember, RV LED lights are the cheapest than can be made and installed. I would make sure that any switch you find can be returned if it does not work. Doug

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