180 minutes or 90 minutes? — The “carpet trap” in robot vacuum battery life

(I) The Birth of the ‘180-Minute’ Claim

At a 2024 flagship launch event, a brand's poster proclaimed in bold: ‘Cleans 250m² homes in a single 180-minute session.’ Fine print clarified: Standard mode, tiled floors, mopping function off, no carpets, 25°C ambient temperature, new product at full charge.

In the lab, engineers removed the side brushes and roller brush, replacing them with ‘empty shells’. The fan speed was reduced to 7000 RPM, current to 0.9 A, and the 2590 mAh battery easily ran for 180 minutes—with 8% charge remaining. The marketing department gleefully stamped “180” on the packaging, and the ‘battery life monster’ was born.

(II) The ‘Carpet Trap’ Field Test

Laboratory figures looked splendid, but reality proved a complete shambles.

In January 2024, Consumer Reports' ‘Real-World Robot Vacuum Testing’ recruited 50 households, distributing identical flagship models rated for ‘180 minutes’. Requirements:

• Start fully charged, default standard mode;

• Homes with 50% tiled floors + 50% carpet (short pile ≤15 mm);

• Fully filled mopping tank with ‘Carpet Boost’ mode activated via app.

Average runtime plummeted to just 92 minutes—a staggering 52% shortfall from the advertised figure. The culprit? ‘Carpet Boost’ mode:

Fan speed surged from 7,000 RPM to 12,000 RPM, with current jumping from 0.9 A to 1.7 A;

The friction coefficient between the roller brush and carpet increases, boosting the main motor torque and drawing an additional 0.3 A;

The mopping module lifts upon carpet detection, yet the bracket motor continuously performs ‘lift-lower-reset’ cycles, consuming extra 0.2 A;

Total power consumption rises from 22 W to 42 W. With the 2590 mAh battery's theoretical energy at 37 Wh, carpet mode devours half the capacity in one go.

(III) The Overlooked ‘Daily Degradation’

Beyond carpets, three further ‘power guzzlers’ lurk in daily use:

• Brush roll hair entanglement: After three consecutive days of operation, accumulated hair thickness reaches 1 mm, increasing torque by 15% and adding 0.25 A to current draw;

• Partially clogged filter: When HEPA dust capacity reaches 70%, air resistance doubles, increasing fan motor current by 0.2 A;

• Deformed side brushes: PET bristles bent by skirting boards reduce sweeping force, prompting algorithms to boost side brush motor duty cycle by 30% for compensatory cleaning (+0.15 A).

After one week, the same household route yields a further drop in runtime from 92 to 78 minutes—a 15% decline—yet users remain oblivious: ‘It charges itself anyway.’

(IV) ‘Mopping Halves It Again’

Many brands implement ‘mopping solutions’ with separate water tanks and vibrating mop pads, pushing power consumption to new heights:

• Vibration motor: 8 W, 3000 cycles per minute—equivalent to a continuously lit torch;

• Electrically controlled water tank peristaltic pump: 3 W, refilling every 10 seconds;

• Overall, the mopping function with carpet detection averages 48W system power consumption, draining the 2590mAh battery in just 58 minutes.

This leads to an absurd scenario:

180 minutes (advertised) → 92 minutes (carpet mode) → 78 minutes (weekly degradation) → 58 minutes (mopping), a fourfold reduction.

(V) Industry Self-Regulation: CLTC-Home Standard

In May 2024, the China Household Electrical Appliances Association released the group standard T/CHEAA 023-2024, nicknamed ‘CLTC-Home’:

Floor composition: 40% ceramic tiles + 40% short-pile carpet + 20% medium-to-long pile carpet;

Simultaneous sweeping and mopping must be activated, with automatic pressure increase in carpeted areas;

Pre-simulate hair tangles (5g) and 50% dust capacity on the filter to mimic one week's usage;

Test temperatures: dual nodes at 20°C and 5°C; labelling only ambient temperature is prohibited;

Cyclic route: 10m straight + 2m turning, repeated until battery <15% triggers return-to-charge.

Initial testing of 12 mainstream models revealed:

• Claimed average runtime: 150 minutes

• CLTC-Home average: 71 minutes

• Maximum discrepancy: 63%

Headlines dubbed it ‘Carpet Exposed’, prompting two leading brands to commit to firmware updates:

• Carpet boost adjusted to ‘two-stage’:

  - Short pile: 20% speed increase only, extending runtime by 10 minutes

• Mopping vibration now ‘intermittent’: 10-second rest after every minute of wiping, saving 1.5W power.

(VI) User ‘Self-Rescue’ Guide

Before comprehensive standards are implemented, consumers can recover 20% battery life through four steps:

Weekly clean brush rollers + filters to maintain factory airflow resistance;

Manually set ‘deep clean’ mode for carpeted areas every other day, using standard mode otherwise;

When mopping, exclude medium-to-long pile carpets to prevent vibration motor idling;

In winter, position the base station in areas above 10°C to reduce battery internal resistance, restoring 8% battery life.

(VII) Epilogue: Preventing ‘180 Minutes’ from Becoming a Numerical Illusion

Robotic vacuum cleaners represent a rare appliance category where battery life directly equates to operational capacity:

• A 10-minute shortfall in washing machine performance remains imperceptible to users;

• An air conditioner can still cool effectively if it runs an hour short;

• But a robot vacuum falling 30 minutes short may leave a 30m² bedroom uncleaned.

When CLTC-Home formally documented the ‘carpet trap’ in its public report, manufacturers finally learned to distinguish between ‘maximum range’ and ‘home range’:

Standard Mode: 180 minutes | Home Comprehensive: 80 minutes

Followed by a line of fine print: Includes mopping + short-pile carpet + one week's dust accumulation — restoring numbers as a credible benchmark.

After all, floors don't lie, and carpets certainly don't.