Sonof SWV Flow Rate Precision

[Sineos]

I just installed a Sonof SWV to monitor my drip irrigation. Unfortunately, the displayed and reported value is always 0. It basically works and displays somewhat plausible values, but with the drip irrigation, the flow is so small that it seems to be rounded down to 0. From what I can tell, the smallest value it shows is 0.1 m³/h, which would equate to a resolution of 100 liters per hour.

Is there any way to switch this to liters per hour or at least 0.01 m³/h?

[Sineos]

I'm trying to get this done via a custom converter, but my coding fu is too weak:

const fz = require('zigbee-herdsman-converters/converters/fromZigbee');
const tz = require('zigbee-herdsman-converters/converters/toZigbee');
const exposes = require('zigbee-herdsman-converters/lib/exposes');
const reporting = require('zigbee-herdsman-converters/lib/reporting');
const e = exposes;

const customFlowConverter = {
    cluster: 'haFlowMeasurement',
    type: ['attributeReport', 'readResponse'],
    convert: (model, msg, publish, options, meta) => {
        if (msg.data && msg.data.hasOwnProperty('measuredValue')) {
            const flowM3h = msg.data.measuredValue / 100;
            const flowLh = msg.data.measuredValue * 10;
			meta.logger.info('SWV flow: ${flowM3h} m³/h, ${flowLh} L/h, ${msg.data.measuredValue} raw');
            return {
                flow: flowM3h,
                flow_L_h: flowLh,
            };
        }
    },
};

module.exports = {
    zigbeeModel: ['SWV'],
    model: 'SWV',
    vendor: 'SONOFF',
    description: 'Zigbee smart water valve',
    fromZigbee: [
        customFlowConverter,
		fz.on_off,
        fz.battery,
        fz.ignore_basic_report,
    ],
    toZigbee: [
        tz.on_off,
    ],
    exposes: [
        e.switch(),
        e.battery(),
        e.numeric('flow', e.access.STATE).withUnit('m³/h').withDescription('Measured water flow'),
        e.numeric('flow_L_h', e.access.STATE).withUnit('L/h').withDescription('Water flow rate in liters per hour'),
    ],
    configure: async (device, coordinatorEndpoint, logger) => {
        const endpoint = device.getEndpoint(1);
        await reporting.bind(endpoint, coordinatorEndpoint, ['genOnOff', 'haFlowMeasurement', 'genPowerCfg']);
        await reporting.onOff(endpoint);
        await reporting.batteryPercentageRemaining(endpoint);
        await reporting.flow(endpoint);
    },
};

I'd appreciate any pointer. Thanks in advance

[Sineos]

I contacted SONOFF support regarding the device's flow measurement capabilities. Unfortunately, the discussion was unproductive: according to their support team, the device only supports a measurement precision of 2 L/h or 0.12 m³/h. Their technical department also confirmed that this limitation cannot be changed.

Personally, I find this explanation somewhat unconvincing. At this price point, it's almost certain that the device uses an impeller and Hall sensor for measurement. In such setups, the resolution is typically determined by the number of pulses counted over a specific time interval. Devices I’m familiar with usually generate between 400 and 3500 pulses per liter. Naturally, the more stable and consistent the flow, the more accurate the readings.

Regrettably, this makes the device unsuitable for modern drip irrigation systems - unless the installation is large enough to exceed 120 liters per hour anyway.

Edit:
I have to commend their support team for being responsive and willing to help; their reactivity was excellent. However, the outcome of the conversation was ultimately disappointing.

What adds to the disappointment is that this significant limitation is not mentioned in the product description for the SWV series. For users intending to use it in low-flow scenarios - like modern drip irrigation - this is a crucial detail.

[X-Ryl669]

Is it 2L/h (as you wrote) or 2L/min (as you implied) ?

Also, the measurement is one thing, but the reporting is another. If you set a 20L irrigation volume, with a drip irrigation, does it respect it? (said differently, with a single 4L/h drip, will it run open for 5 hours?).

It's possible the reported flow rate follow the Zigbee "Flow" protocol, which implies 0.1m3/h unit (pretty useless), but the device is able to measure much finer, but can't report it.