BlitzWolf BW-SHP13 precise power value?

[vogler]

How is the power value computed? It seems useless/wrong. I connected a 9W LED and it reported 2 and 4 whereas current * voltage = 9.28W seems to be better:

{"current":0.04,"linkquality":68,"power":2,"voltage":232}
{"current":0.04,"linkquality":68,"power":4,"voltage":232}
{"current":0.04,"linkquality":65,"power":2,"voltage":231}
{"current":0.04,"linkquality":65,"power":4,"voltage":231}
{"current":0.04,"linkquality":68,"power":2,"voltage":231}
{"current":0.04,"linkquality":65,"power":4,"voltage":231}
{"current":0.04,"linkquality":63,"power":2,"voltage":232}
{"current":0.04,"linkquality":63,"power":4,"voltage":231}

I assume power is reported by the device like that, but why if it has more precise values?

Debug info

Zigbee2MQTT version: 1.16.1-dev (commit #b1b134f) Adapter hardware: CC2531

[Koenkk]

Added this option now, you can set this by clicking on the device in the frontend -> settings (specific). The value is percentual, e.g. filling in -10 will decrease all measurements by 10%.

Changes will be available in the dev branch in a few hours from now. (https://www.zigbee2mqtt.io/advanced/more/switch-to-dev-branch.html)

[Sungtroll]

I suppose you mean for the power only, if you want to correct the Volt and Ampere too then you have to include correction for those seperatly.

[Koenkk]

@Sungtroll for all 3, you can configure it seperately.

[github-actions[bot]]

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[manny199]

I have a bit of a weird problem. My Blitzwolf BW-SHP13 plug does not detect watt below 10 watt. Basically, the value it shows with consumption below 8/10 watts is equal to ZERO. For example, if I put a webcam it does not detect its consumption in watt. Do you have a solution to this problem? The Plug is detected as TS011F_plug_1 and the firmware has been updated. The production is _TZ3000_amdymr7l

[NightMean]

I tried the newer BW-SHP15 (external converter here) works much more precisely for me. Nevertheless, there should be a configurable multiplier for the BW-SHP13.

I've ordered couple of BW-SHP15 but it seems the measurement is also not correct. While I know this thread is about active power and not volts, I thought I might as well add my findings to this topic. I don't have anything fancy, just a multimeter but I measured constant 240V on the wall socket. The measurements from the plug itself differ quite a bit. One plug measured 239V, second 247 and third 250V.

It'd be really helpful to have some correction for each plug.

Edit: Just as an FYI, as the measurement is not correct the plug switches off at 260V due to its protection which is not really helpful in this case. Short spikes are unfortunately not visible in graphs but the plug did turn off itself.