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Controlling 12-volt heaters with a power relay

Home Forums Infrastructure and Equipment Controlling 12-volt heaters with a power relay

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    • #18453
      Braedon
      Participant

        I have some apogee pyranometers and pyrgeometers for my monitoring stations, and each of these sensors has an internal heater that helps to clean off snow, rain, and frost. The heaters operate at 12 volts, so I have them connected directly to my 12-volt battery which powers my entire setup. Having the heaters connected 24/7 draws a lot of power relative to the other sensors and instrumentation I am using, which quickly drains my batteries. I would like to move to a less frequent logging interval (going from every 15 minutes to every 60 minutes), and I would like to potentially power the heaters on my sensors for less time, for example for the 15 minutes leading up to my new logging time (on the hour). Because these heaters need a 12-volt supply, my understanding is that using a power relay could be an appropriate tool for controlling these heaters with a signal from the Mayfly while still having their power source come directly from the battery.

        There are quite a few relays out there, and I’ve seen some previous discussion posts with references to Seeed’s website (https://wiki.seeedstudio.com/Seeed_Relay_Page/). I’ve also seen lots of relays on Adafruit, such as the following which seems like a good option from my limited knowledge in this area: https://www.adafruit.com/product/2923. I wanted to run this by the EnviroDIY community to get some input or suggestions. Also, from what I’ve read, it seems like a latched relay will help me save on power, which is really important for this implementation, and the Adafruit example has that option as well.

      • #18456
        Shannon Hicks
        Moderator

          What’s the current draw of your heaters?  There’s a variety of relays you could use, but I know several people have had good luck with various Grove-compatible relay boards, like the ones from Seeed.  But your options are going to depend on how many amps of current the heater draws from the battery.

        • #18457
          Braedon
          Participant

            I have four sensors with heaters, and combined they draw 61.6 mA.

            • #18458
              Shannon Hicks
              Moderator

                That’s not much current, so most relay boards should be able to handle that with no problem.  I think that latching Grove board (https://www.seeedstudio.com/Grove-2-Coil-Latching-Relay.html) would probably work good for your situation so your Mayfly board could activate the relay 15 minutes before you want to sample, and then go back to sleep and it won’t have to hold a pin high to keep the relay closed.  You can connect the relay board to the Mayfly via one of the unused Grove jacks (but make sure you set the voltage selection jumper next to that Grove jack to 5v since the relay board operates at 5v).  I’m sure there are other latching relay boards out there that would work as well, but the Grove jack makes wiring it up convenient.

            • #18459
              Braedon
              Participant

                This looks like a great option. Thanks Shannon for your help!

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