Is this my fridge’s defroster?

My Sense detected a new device on Saturday, and back populated the data through mid May of this year. I’m pretty sure this is my new Samsung refrigerator that I installed on May 9, but curious as to what aspect of the fridge this might be. It was identified as a heating device: 22% probability dishwasher, 10% lightbulb, 10% jacuzzi, but I know it’s none of those. It runs about 15-20 minutes each day, but not every day (it hasn’t run at all in the last three days) and on two occasions it ran twice in the same day. My initial thought is it’s the defroster unit in the freezer, but do they really run this often? Seems like a lot. Does anyone recognize the power signature of this?


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I don’t have any first-hand knowledge of this, but I have read that newer fridges will run the defrost based on when it’s most appropriate rather than just on a timer. That means that if the freezer spends more time open, and if the air that gets into the freezer when it’s open is more humid, the defrost cycle will run more often.

If you have a built-in ice maker, those also frequently have a heat component to release the ice, but it wouldn’t run for 18 minutes as your waveform shows.

If you can find a service manual for your fridge model, you might be able to manually trigger a defrost cycle. Then compare that to Sense. Here’s a YouTube video about a guy triggering a defrost manually (starting at around 6:06):

This looks a lot like the defrost on my Sears (which I think was made by Samsung…perhaps LG) three door unit. These refrigerators generally aren’t detectable (mine hasn’t been in a year) by Sense because they don’t actually turn on and off, they ramp up and down proportionally as needed. There are a few pieces that do get detected, notably the ice maker motor, the ice make release heater, and the defroster. So, many of us have hooked the refrigerator to an HS110 and then to Sense to get actual consumption. You can also see charts which show the total power usage.

The defrost on mine varies significantly, depending on our use. AFIK, it’s not on a timer at all, it runs when it needs to and even how long it needs to.

Looks similar to the fridge defrost cycles in the library…

My 6 month old LG fridge hasn’t been found yet either, but my defroster has. It starts at 500 watts exactly, then drops to 315 watts about 2/3 the way through. Mine runs for 27 minutes. I figured it out because the manual said no cooling would happen during that time, and using a notification from Sense, I would check the fridge during that range and never found it cooling.

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Here’s last month on my Blomberg fridge (on a Wemo) …

I count 26 defrosts in 30 days ==> 27.7 hrs average between defrost cycles. Looks to be typical.

Meanwhile, here’s 30 days in January when we were away until mid-month.

Pretty classy appliance. And the defrost patterns look as I’d expect for a modern high end refrigerator. Bet these cooling units won’t show up all that well on Sense, but it should be able to catch the defrost and ice maker. I’ve had excellent results with the TP-Link HS110 tracking my two year old Sears.