Cheap power meter with clamps for washing machine and dryer

Hardware
1

Hi,

so as the title says, I want to automate my washing machine and dryer. Neither has any kind of connectivity. And I don’t need anything fancy. I just need to know when they start and when they finish. When the dryer starts I turn on a pipe fan. And when either of them finish I get a push notification on the phone. I don’t care about power consumption or anything else.

I have this setup already with smart plugs. However, I have a problem with these. Both of these machines can have high peaks for a split second, and that trips the smart sockets and they switch off. I have 20A sockets (although cheap Tuya AliExpress ones), but they still trip. I setup an notification when that happens. Sometimes it reads 24-25A just before they turn off. The measurement of that is questionable, since I’ve had both of these machines connected without smart sockets, and they never blew a 16A fuse. It doesn’t happen every time, but it’s quite often, 1/3-4 times it happens, dryer especially.

I don’t want to experiments with sockets anymore. I don’t know which ones to get to be 100% sure they won’t have the same problem. I think a power meter with clams is a safer option. Basically, what I need is Shelly EM, but I don’t want to spend that much money. Preferably Zigbee, but I can live with WiFi as well.

If Zigbee, it needs to work with ZHA. I don’t have Zigbee2MQTT. I’ve looked at these ones https://smarthomescene.com/reviews/tuya-zigbee-single-clamp-energy-meter-review/. There is a custom quirk for these, although I’m not 100% sure it works for all models. I have seen a thread somewhere where people complained that they couldn’t get it to work.

I’ve had a look at those with WiFi, but found a thread where people are having problems getting readings out of those as well. They do get recognized, but show no entities. I’d also like to avoid Tuya/LocalTuya, if possible.

Another alternative is to build it with ESP CT Clamp Current Sensor — ESPHome. However, I’m not sure which hardware to get. I have a few ESPs lying around, but I’m not sure about the rest of the hardware. I need a current sensor with inputs for 2 clamps. I don’t want 2 separate boards, since I don’t have a lot of room where to put this. And I’m also not sure which clamps to get. Some clamps, even on AliExpress, are quite expensive. If this whole things costs me just slightly less than a Shelly, I might as well get a Shelly then.

Does anyone have a suggestion?

2

Just an explanation here
A fuse is a slow device. It can have some abuse for a few seconds before blown. A smart socket is much faster.

I have a few suitable power clamps for you but postage is rather expansive to other countries. (I am in The Netherlands) They can be connected to 1 ESP. Please PM me otherwise.

3

I’m from Croatia, so yeah, the shipping is probably more expensive than the clamps themselves. Can you link which clamps you are talking about, maybe I can find them somewhere? AliExpress and Amazon (if I order more stuff to be eligible for free shipping) are probably my only reasonable options.

But it’s not just the clamps. I need a current sensor with 2 channels, right? All the tutorials I’ve seen use this one, which is a single channel

4

The current sensor you mention is just a resistor.

You need something like this
SCT-013

They aren’t expensive and there are many threads and connection diagrams on this forum to find

5

You don’t need current sensor, your clamp is the sensor. But you need to offset the AC negative voltage, so you need few resistors and a capacitor.

Also be avare that the clamp has to be on a single wire, not on cable.
Wired option (no clamp) could be ACS712 30A
My vote goes for Shelly Em. Wait for black friday…

1 Like
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That is my main problem with the ESP. I can write the firmware for it easily, but electronics are not my strong side. Resistors, capacitors etc. I’m completely stupid for those things, and all that I can do is just blindly follow instructions. On top of that, I need to fit this into a really small space, so I’m not sure DIY is the way to go.

I’m still tempted to order one of these and see if I can get the quirk working. There is a much higher chance of that, than soldering electronics.

Waiting for black Friday is not bad advice, although I don’t expect much from Shelly. They have really jacked up the prices in the last few years. I remember buying their relays for under 10€ a piece. Now it’s almost triple. Every time I order something it’s at least 30% more than it was last time, so I come to dislike them quite a bit

7

I agree but still prefer paying double for Shelly vs Tuya. What about that ACS712+Esp?
Some people use battery powered vibration/temperature sensors.