Shelly 1PM and 2.5 power usage when powered on 24VDC

[Shaad (David)]

Hello,

Does anyone know if we are supposed to get a working power metering when powering Shelly 1PM or 2.5 on 24VDC instead of usual 110 or 230VAC ?

I have about 10 Shelly 1PM and 2.5 working fine on 230VAC. I need to add 2 on 24VDC. They work fine but never update the power usage of the relays. Is this a hardware limitation due to how DC current work ? or a software limitation ?

Thanks,
David

[Jonah1970 (Mark)]

Hi, I suspect that this may be a limitation in the way that power measurments are derived using CT’s (Current Transformers). These use a coil and magnetic core around the main conductor to induce a signal that is proportional to the AC current that is flowing which is proportional to the power. It will not work properly for DC circuits.

If your load is fairly constant then you can approximate the power usage by integrating this constant value while the switch is on e.g. if you had a 1kW load switched on for half and hour than the power used would be 0.5kWh.

The following post gives an example use case:

Calculate power usage

Have an electric heater controlled through MQTT in HA. They are basic switches with reporting of 0 and 1 for on/off. As i know their energy consumption (700w) i would like to calculate their hourly/daily usage. Seems it cannot be done with HA directly. Installed influxdb with grafana but seems i cannot do that either (if possible maybe a hint?) So which history component i should use for that?

[maxym]

AFAIK power metering is available only for AC. It was confirmed on Shellies forum some time ago

[Shaad (David)]

Thanks to both of you !