Hello all, I've built an RV with many compartment doors and opening skylights and so on. I'm trying to come up with a good idea preferably off the shelf but open to building it myself way of getting a visual light or audible alarm in the cab if any doors are left open or come open during operation. My thought is something like an automotive door jamb button wire to an open/closed circuit sensor preferably battery operated that transmits wirelessly to something in the cab to turn a light or alarm on or off. Trying to avoid running huge bundle of wires throughout the entire vehicle for each switch. Any ideas would be greatly appreciated thank you!

 

For the cabinet doors only 1 conductor would need to pass through each closed switch back to the battery.
This wire when open could activate a relay or transmit module to alert the cab.

 

I was wondering about putting solenoid locks on them so that whenever the cable connects to the towing vehicle it locks all the cupboards.

 

Wired switches are passive, don't require power and can be almost invisible (or easily hidden) with the small currents needed here.. As was said above, only one wire is needed for each detection area, that can have several switches that ground the one wire to the chassis frame common to light a LED/ alarm buzzer/etc ... connected to the + voltage side.

 

For the cabinet doors only 1 conductor would need to pass through each closed switch back to the battery.
This wire when open could activate a relay or transmit module to alert the cab.

What would be the transmit module?

 

Wired switches are passive, don't require power and can be almost invisible (or easily hidden) with the small currents needed here.. As was said above, only one wire is needed for each detection area, that can have several switches that ground the one wire to the chassis frame common to light a LED/ alarm buzzer/etc ... connected to the + voltage side.

This would work for most of my compartment doors but getting a wire to the roof hatches is problematic which is why I was hoping to find a wireless system. Just something when the hatch was open it would trigger a transmitter to a light in the cab.

 

What would be the transmit module?

Could be something like This with the button transmitter modified. The relay receiver can activate a light in the cab.
Another suggestion is using the "alarm" circuit to activate the trailer lights if the 7 pin wiring harness is accessible.
Is this a towable RV?

 

No wiring is the way to go. You can buy cheap 433Mhz transmitter modules that have a zero standby current. Powered by 3V so a lithium coin cell will do. They only use power when triggered (normally by a button) - just like a key fob.
Something like this.
I would use a magnetic reed switch as the switch and mount a small magnet on the window or door.
You will need some sort of simple CMOS logic (with zero static current draw) or a micro-controller (which sleeps when not triggered) between the reed switch and the TX module because:

• The reed switch will be closed when the door is closed and you want the TX to be triggered when it opens.
• When the window or door is intentionally open, you don't want to drain the battery too fast.

So something that could produce a short pulse every few minutes when the switch is open would do it. Possibly something as simple as a CMOS 555. Mount it all in a small plastic box next to the magnet.
I wouldn't be surprised if someone already makes something like this!
The receiver - another cheap module - would sound an alarm if a pulse is received.
You could add sophistication by having each transmitter send a unique code. Your receiver could then have a display to tell you which door is open!

 

IMO rigging a wireless system would not be easy either. By the time it takes to buy, install, troubleshoot the cheap 433Mhz modules, move things around so the wireless link is reliable, and hide all the boxes, you could have easily run a dozen wires (small gauge) using a snake, under trim or under tape to the most inaccessible parts of the RV and never need to worry about dead batteries or unreliable RF modules for the life of the RV.

I'm not much a believer in wireless for security or safety systems. Too easy to fail and too easy to crack.

 

Instead of a wired or wireless link, how about an indicator light that is visible in the rear view mirror. I have also seen an indicator light in that position showing that the electric brakes are being powered, with the brightness providing an indication of the voltage. That does double duty because if the light comes on full brightness as soon as the brakes are touched it means the brake magnets are not connected. Either one of the several conditions is good to be warned about prior to getting under way.

 

Instead of a wired or wireless link, how about an indicator light that is visible in the rear view mirror. I have also seen an indicator light in that position showing that the electric brakes are being powered, with the brightness providing an indication of the voltage. That does double duty because if the light comes on full brightness as soon as the brakes are touched it means the brake magnets are not connected. Either one of the several conditions is good to be warned about prior to getting under way.

What's this indicator light going to powered with? Wire, battery, Hope?

 

The light indicating "that something is open" would be powered by the trailer 12volt battery. (I am assuming that the RV has a 12 volt battery to power lights and a vent fan and the water pump) . OR whatever would be powering the wireless warning system. The electric brake indicator light is powered from the electric brake positive control signal , at the RV terminal block, from the vehicle brake controller. The electric brake monitor negative connection is the "ground" wire in the 7 pin connector.