I have an air compressor that I often give difficult tasks, where the compressor needs to run longer than it was designed for. So it gets close to overheating, which requires periodically giving the compressor some "cool down" time, turned off.
Rather than walk into my garage every couple of minutes to turn the compressor on or off, I'd like to automate the process with a little arduino board.
The problem is the compressor is run by a 25A 12V DC line. Most relays I can find that are Arduino compatible (3.3v DC control) max out at 10A.
I'm curious if there is a smart way to do this efficiently. Two solutions that come to mind are:
Control 3 or 4 10A relays with the Arduino, and parallelize the current heading to the compressor across multiple relays.
Use one relay controlled by the Arduino, and use that relay to control a secondary big relay, that could control the 25A line.
Neither seems like a very efficient approach to the problem. I don't know for certain but I worry that perhaps with (1), one relay might be a better conductor than the others, so perhaps one might eventually see a cascade of overheating relays.
Perhaps someone here that's more familiar with circuit design could suggest a better approach.
edit: After a little digging it looks like option (2) is the standard route most often traveled.
This is an OMRON relay that is powered by a 12VDC supply (0.167A), and can switch a 28VDC 30A line. So I will double relay it, using an Adafruit featherwing to switch the 12VDC supply, which will then switch this big OMRON relay. In my pile of old AC/DC converters I found a 1A 12V supply that's sufficient to run the OMRON relay. Provided I haven't overlooked anything this is likely a decent solution.