How to measure robot vacuum and dock electricity use
Electricity cost comes from the energy used by the complete system, not maximum motor power. A dock may charge, wash and dry at different times. One instantaneous watt reading during a cleaning pass does not describe daily consumption.
Choose the quantity you want to compare
| Result | Calculation | Use |
|---|---|---|
| kWh per complete cycle | Final reading minus starting reading | Compare modes under similar conditions |
| Weekly kWh | Reading after seven days minus the initial reading | Price a real routine including standby |
| kWh per cleaned square metre | Energy of complete cycles / their combined cleaned area | Compare with a clearly defined area basis |
Prepare the measurement
Use a finished plug-in energy meter suitable for the local supply and appliance load, preserving any required protective earth. Do not open electrical installations or alter the dock cable. Follow the robot’s manual: for example, Saros 20 should not use a supply that regularly switches its power off. Measuring energy does not require a timed socket schedule.
Record model, cleaning mode, washing and drying settings, floor area and date. Note the starting kWh rather than assuming the counter was reset. If the meter has coarse energy resolution, a very short trial may be too small to compare meaningfully.
Use comparable start and finish conditions
Compare periods that begin and finish at a similar battery level. Ending trial A immediately after floor cleaning and trial B after recharging and drying measures different workloads. Record both the end of floor cleaning and the end of dock servicing. Repeat the trial instead of drawing a conclusion from one run.
A calculation using illustrative readings
Suppose a meter increases from 12.40 to 14.50 kWh in seven days. Consumption is 2.10 kWh. At an illustrative variable tariff of €0.30/kWh, that is €0.63 for the measured week. Extending exactly the same usage to 30 days gives 9.00 kWh and €2.70. These are invented inputs demonstrating arithmetic, not a claim about typical robot costs.
Include the bill components that actually change with energy consumption in your unit rate. Do not allocate the home’s fixed charges to the appliance twice. Time-varying tariffs require the relevant usage breakdown; one average price is a simplification.
Your weekly recording sheet
Record date, starting and final kWh, cycle count, floor area, drying settings, additional washing, errors and interruptions. Days without cleaning still belong in the real running cost. Compare two docks against the same cleanliness goal, rather than assuming identically named modes deliver the same task.
Next step: enter measured electricity use into the annual maintenance calculator. A week describes the routine you observed; a change in season, cleaning frequency or drying requires an updated assumption.
Continue with the next step
Sources and scope
Documentation checked on 11 September 2026. Worked examples and worksheets are RoboMorrow editorial work, not results from hands-on device tests we performed.