Making a none IOT Washing Machine and Tumble Dryer semi smart

The situation:

I have a Washing machine and Tumble dryer, and I need to know when they have finished washing / drying so I can get on with more fun laundry. The problem is they are in an out-building, and the built in beeping cannot be heard in the house.

They are also the kind of appliance which weighs the contents, detects moisture levels etc and dynamically adjust the amount of time they need to run. So when I set them running and set a timer for when they are due to be finished, they will either have finished 20 minute before or still have 20 minutes left to run.

The solution:

The solution runs on home assistant

1. get a smart plug which can monitor power consumption, I used TP-Link wifi smart plugs because zigbee wouldn’t reach the out-building.
2. create a new boolean input helper and name it isWashingMachineRunning
3. create an automation which is triggered when the power consumption on the washing machine is greater than 10w for 10 seconds, and set it to toggle the isWashingMachineRunning state to true
4. create a second automation which is triggered when the power consumption of the washing machine drops below 10w for 1 minute, then:
   1. change the state of isWashingMachineRunning back to false
   2. send a notification to my phone
   3. send a notification to my smart speakers via notifyMe

Repeat for Tumble dryer.

The reasoning:

I tried to send the notification based solely on when the power consumption dropped below a level, which would remove the need for the boolean input helper and one of the automations. However I found that this would send a lot of false positives, I’m guessing the plugs would temporarily loose wifi signal and when they reconnected Home Assistant would detect the power consumption at 0 and issue the notifications. Not fun a 4am.

I initial attempted to avoid the 4am wake ups by altering the automation to only send notifications during the day, but the random notifications during the day were still not ideal.

Finally I settled on setting an on or off state using automations, and the system is self recovering, if the plugs loose connection, or home assistant goes down temporarily, when everything comes back online the states will get set correctly and notification sent. The only possible failure would be if the plugs/home assistant went down for the full duration of a wash/dry cycle, be I’ve yet to have that happen in over a year of running this setup.