I’ve followed a few threads on dryer activity sensing, and my dryer is just quirky enough that it makes a lot of sense to try. This thread talks about motion sensors, vibration sensors and smart plugs. All good ideas (except that in the US most dryers use a heavy-duty outlet that’s harder to fit with a smart plug.)
But how about this one: Just use a temperature/humidity sensor? I’m thinking that would provide all the information I need. If the humidity drops, the clothes are dry and I can stop the cycle now, saving energy. If the temperature drops, the dryer has stopped heating and the clothes are probably dry. If the temperature drops and the humidity stays high, the sensors in my dryer are messed up again and I need to start a new cycle.
For me, a Zigbee sensor would be ideal. I find these easier to set up and more reliable than WiFi. Plus, they can run for months on battery. The only problem I foresee is that the signal may not get through the metal dryer. But I haven’t tried, maybe it will. In my case, there’s a mains-powered Zigbee smart plug very near the dryer, so I’m hopeful.
In addition to what @tom_l said, I can think of one way that might at least give your sensor a better chance at life. If you place it where the dryer vent outputs the house, you might be able to do something like what you are thinking. Inside the dryer, no, don’t do that. Batteries explode at higher temps and yeah… not good. If you can place the sensor near where the dryer vent is, then the temps will be lower and not quite as bad on the battery.
Ohhhh, I just thought about something else that might be even better. Get a Sonoff TH-16 (https://www.amazon.com/Docooler-Monitoring-Temperature-Automation-Compatible/dp/B07QH256XW/ref=sr_1_5?dchild=1&keywords=sonoff+temp&qid=1613671963&sr=8-5) and place the sensor probe into the open end of your dryer vent. You can wire the sonoff into any type of 16-18ga wire (I typically buy cheap extension cord and wire Sonoffs into those) and power it that way. The benefit here is that you don’t have to worry about exploding batteries and other things like that. I think Shelly makes a 20amp appliance module that you can splice inline to your dryer and use that to remotely turn on/off the dryer as needed.
It’s not a perfect solution, but it’s a cheap, doable one that is a lot safer than a temp/humidity sensor with a battery.
I think so. My neighbor across the street has a dryer from the 80s that only has a timer on it. He was so pissed when I bought my wife her new SmartThinQ washer and dryer. LOL
I like it!! I’d prefer a Zigbee solution, but Sonoff stuff is pretty reliable either way, and this certainly isn’t a critical system, so WiFi will be sufficient. I see no reason that probe couldn’t be tucked inside the flexible vent duct. I wasn’t planning to turn the dryer on and off, although I could see maybe wanting to do that in the future.
Mine is probably highly efficient. In other words, full of complicated sensors and programming that are prone to failure. I’d take the old-school mechanical timer any day.