Tapo P110 does NOT give you an accurate estimate of electricity usage

MattMattMattUK

Eldi_Dos said:

@MattMattMattUK:
                Why would you want eight of these Tapo devices, most of us are trying to cut down on consumption.

They all measure different things, some are also used as smart plugs, turning things on and off as required. Their power usage is so small as to be irrelevant, so that is not a concern. 

chris_n

Andrea15 said:

CSI_Yorkshire said:

It's possible.  How big a spike are you talking about?

This spike. Same thing happened yesterday. 
(I had to reconfigure it because for some reason it couldn't be found. That meant moving the washing machine )

Looks normal for a washing machine. Heater on at start of cycle then wash, stop drum, empty and refill, rinsing cycle, stop drum then do spins with pauses (often reverses) to untangle clothes.

frostysaver

Andrea15 said:

... running my washing machine on my usual cycle (30 °C, 2.5 hrs approx) and the Tapo says I have used up about 0.55kWh. However, looking at the meter I know that the usage is approx. 1 kWh (and yes, I have taken into account background usage, and yes I have repeated the experiment).

How did you try to take into account other usage in the home? This will be difficult and inaccurate, as some usage will be intermittent, eg fridges and freezers.

I think it's more likely estimation is inaccurate, rather than the device (given other readings suggest it's not broken).

Washing machine cycle consumption is usually quoted in the manual, for a comparison value.

Andrea15

frostysaver said:

Andrea15 said:

... running my washing machine on my usual cycle (30 °C, 2.5 hrs approx) and the Tapo says I have used up about 0.55kWh. However, looking at the meter I know that the usage is approx. 1 kWh (and yes, I have taken into account background usage, and yes I have repeated the experiment).

How did you try to take into account other usage in the home? This will be difficult and inaccurate, as some usage will be intermittent, eg fridges and freezers.

I think it's more likely estimation is inaccurate, rather than the device (given other readings suggest it's not broken).

Washing machine cycle consumption is usually quoted in the manual, for a comparison value.

I have been monitoring it for some time, so it is a reasonable estimate. Besides, when I do the same experiment with the dishwasher I get the expected value.
Alas, I couldn't find any consumption values for my washing machine as it is too old, and I don't know what I have done with the manual (assuming there was a time when I had it)

Andrea15

chris_n said:

Looks normal for a washing machine. Heater on at start of cycle then wash, stop drum, empty and refill, rinsing cycle, stop drum then do spins with pauses (often reverses) to untangle clothes.

The first spike looks rather odd, though. How can I measure 2 kW? Interesting how the consumption decreases. There is a spike at the beginning and then it goes down. it could be the water warming up, I suppose.

MattMattMattUK

Andrea15 said:

chris_n said:

Looks normal for a washing machine. Heater on at start of cycle then wash, stop drum, empty and refill, rinsing cycle, stop drum then do spins with pauses (often reverses) to untangle clothes.

The first spike looks rather odd, though. How can I measure 2 kW?

Kettle, hairdryer or a fan heater are all potentials, something with a stated rating and a high draw for generating heat, though do not expect them to run exactly at their stated rating, but they should be close.

Andrea15 said:

chris_n said:

Looks normal for a washing machine. Heater on at start of cycle then wash, stop drum, empty and refill, rinsing cycle, stop drum then do spins with pauses (often reverses) to untangle clothes.

Interesting how the consumption decreases. There is a spike at the beginning and then it goes down. it could be the water warming up, I suppose.

Heating element running at the start, the rest is just the motor and pump occasionally kicking in, the smaller spike at the end will be the motor on spin. 

chris_n

MattMattMattUK said:

Andrea15 said:

chris_n said:

Looks normal for a washing machine. Heater on at start of cycle then wash, stop drum, empty and refill, rinsing cycle, stop drum then do spins with pauses (often reverses) to untangle clothes.

The first spike looks rather odd, though. How can I measure 2 kW?

Kettle, hairdryer or a fan heater are all potentials, something with a stated rating and a high draw for generating heat, though do not expect them to run exactly at their stated rating, but they should be close.

Andrea15 said:

chris_n said:

Looks normal for a washing machine. Heater on at start of cycle then wash, stop drum, empty and refill, rinsing cycle, stop drum then do spins with pauses (often reverses) to untangle clothes.

Interesting how the consumption decreases. There is a spike at the beginning and then it goes down. it could be the water warming up, I suppose.

Heating element running at the start, the rest is just the motor and pump occasionally kicking in, the smaller spike at the end will be the motor on spin. 

My daughters washing machine profile is exactly the same, there is an @2kW heater in the washer.

Eldi_Dos

CSI_Yorkshire said:

Eldi_Dos said:

CSI_Yorkshire said:

Eldi_Dos said:

@MattMattMattUK:
                Why would you want eight of these Tapo devices, most of us are trying to cut down on consumption.

To measure eight different things at the same time.

The power consumption of the device itself is effectively zero.

I was meaning consumption in the broader sense not just power consumption.

And if you want to measure 8 things at once, having 8 measurement devices is a requirement.  Failure to fulfil a requirement is not a good argument for reducing consumption.

That may well be the case if you are compiling reports that have to be verified but that would call for the devices to be part of a calibration system, which I do not believe is the case in this instance, so not really a requirement.
If you are just wanting to know the power consumption of individual pieces of equipment for your own benefit one or two would suffice as you could swap around as need be.

Eldi_Dos

MattMattMattUK said:

Eldi_Dos said:

@MattMattMattUK:
                Why would you want eight of these Tapo devices, most of us are trying to cut down on consumption.

They all measure different things, some are also used as smart plugs, turning things on and off as required. Their power usage is so small as to be irrelevant, so that is not a concern. 

The power usage while in use may appear irrelevant but they will most likely have been produced in a economy that is powered by power stations that are very far from green. The evidence of the damage that this is causing is a almost daily part of the news.
Buying eight items when one or two would carry out the same function adds to the problem and should be of concern.

MattMattMattUK

Eldi_Dos said:

MattMattMattUK said:

Eldi_Dos said:

@ MattMattMattUK:
                Why would you want eight of these Tapo devices, most of us are trying to cut down on consumption.

They all measure different things, some are also used as smart plugs, turning things on and off as required. Their power usage is so small as to be irrelevant, so that is not a concern. 

The power usage while in use may appear irrelevant but they will most likely have been produced in a economy that is powered by power stations that are very far from green. The evidence of the damage that this is causing is a almost daily part of the news.

They use around 10kWh a year, an irrelevantly small amount of impact. Now they are made in China which does produce a relatively large amount of it's energy from coal, so there is that impact, but there is also not an alternative that is made in non-polluting country.

Eldi_Dos said:

Buying eight items when one or two would carry out the same function adds to the problem and should be of concern.

One or two would not carry out the same function though because one or two will not carry out simultaneous monitoring across multiple devices, whilst also operating as smart plugs on other devices. Now you could argue that the continuous monitoring is not something that I need, but that is a different argument.