Calibrate Sonoff POWR2

[mrb13676]

I'm assisting my daughter with an efficiency project for school where she's measuring how much energy it takes to iron vs steam vs tumbledry clothing.. anyhow that isn't really relevant except that I need a reasonably accurate power meter.

I have a number of Sonoff POWR2's and I've hooked one up to a known load but it's under reading the wattage which will affect the Riemann integration KWh meter in HA. The bulb is 40W and it reads 32 - i.e a 20% underread.

Is there any way to calibrate this or add an adjustment without tasmotising it (I dont really have the ability or desire to solder the board on this device).
Should I rather get a Shelly to do this?
Mike

 

[hilton]

You are assuming the bulb is actually 40W. Do you have the 16/5A version though? Just don't use it to switch just pass through the current. Plug something else in to test.

 

[bwana]

Get a Kill-o-watt instead. It’s purpose built for the job.

 

[mrb13676]

OK I have solved this by making a template sensor to push out a calculation result using value_template to adjust the reading based on a number of test loads. Thanks.