Another garage parking aid

Looks like this is a pretty standard first arduino project for many. (It's my second.) I've completed packaging my components and am satisfied with the test environment operation of my code. I'm using UNO and a relay board to drive a R-Y-G stack of lights. Here's my question: installation is in an unheated detached garage in a cooler climate (Wisconsin - below 0 degF quite common in winter). I'm concerned about the standby state of the system. My choices: 1) control power to my system via a control power relay controlled by the garage door overhead lamp - it comes on when door is moving and stays on for a few minutes afterwards; or 2) leave system on 24/7 and detect "no movement" in software and turn off all lights. I have no concerns (nor have I observed) spurious operation when cycling power in my test setup. I've read on the forum concern being energizing the system from power off very cold. Is this worse than 24/7 operation in same conditions? UNO is in weatherproof box in the garage. Absent any strong recommendations, I'll pick one and see for myself ... but I welcome experienced guidance.

And thanks in advance for considering my question.


The microcontroller chip itself is rated for -40C - +105C and if your using a genuine arduino the other components will likely be ok also.

A much bigger issue is condensation which can definitely cause issues if not taken into account.

One way to deal with condensation is to use a conformal coating which will prevent any moisture from reaching the components and allow you to turn off the system without worry.
A second option is to leave it run 24/7. If a small enough enclosure is used the heat generated by the arduino may be enough or you could add a small incandescent bulb to generate more heat.

OK, good info. I already purchased a bottle of the silicone conformal coating which I used on some moisture detectors (the electronics, not the sensor zone, not this project), and coated the electronics on my ultrasonic board. I could give a good coating to the arduino board before it gets permanently placed in the garage.

It was probably overkill, but I got a pretty beefy dual 5v/12v power supply for the board and lamps. I was concerned about heat removal and have run it for several days in the house with the signal lights on to draw maximum current. The enclosure gets warm, but not at all to what I’d think would be a concern. Maybe this in itself would lead me to think this would be the better choice.


There are pro’s and con’s to both methods. The coating can make it difficult to service or update and the other is susceptible to power outages. Always a compromise.

tennis ball and a string.