Robot vacuum battery life and runtime explained

What runtime figures mean

Makers measure runtime under the easiest conditions: lowest suction, hard floor, no mopping. Real cleaning uses more power, especially with carpet boost, max suction or mop pressure. As a rough guide, expect noticeably less than the headline figure on a mixed home.

Some listings give area instead of minutes, which is more useful. The Dreame L40 Ultra Gen 2, for example, lists up to 231 minutes and 1,600 m² in quiet mode, and the Roborock Qrevo 5AE dock mentions refilling for cleaning over 330 m². Use whichever figure you have, but treat it as a best case.

Runtime on current listings

These figures come from Amazon UK listings. They are best-case figures for comparison.

Will it finish your home on one charge?

Add up your floor area room by room and compare it with the robot's coverage. Our floor-area adder does this in square metres or square feet and tells you how many charges a robot needs. Most UK flats and small to medium houses fit comfortably within one charge for any current lidar robot.

Larger homes and those with lots of carpet may need more. That is not a problem with recharge and resume: the robot returns to the dock, charges enough to finish, then carries on where it stopped. Shark, Roborock, Dreame, Eufy and Ecovacs all list this feature on mapping models.

What drains the battery fastest

Max suction and carpet boost use the most power. Mopping with rotating pads under pressure also adds load, as does a long run of edge cleaning. Thick carpet slows the robot, so it covers less ground per minute.

If your robot keeps running out before finishing, try standard suction with carpet boost only, clean busy rooms more often and quieter rooms less, or split the home into two scheduled runs. Check that the brushes are not clogged, as a jammed brush also draws extra power; see brush not spinning.

Battery health over the years

Robot vacuums use lithium-ion batteries, which slowly lose capacity with charge cycles and age. After a few years, a robot may only manage part of its original runtime. Keeping it docked between runs is fine; modern robots manage charging themselves.

Most robots have a replaceable battery, often under a panel on the underside. Our guides to battery replacement and how long robot vacuums last cover when and how.

Note:Use the correct battery for your model from the maker or a reputable supplier. Stop using any battery that swells, smells or gets very hot, and recycle old batteries at a proper collection point.

Mopping and runtime

On combo robots, mopping affects runtime in two ways. Spinning or roller mops under pressure draw extra power from the battery, and the robot may return to the dock mid-run to wash the mop and refill water, which adds time but also lets it top up its charge. Some docks, like the Ecovacs X12 OmniCyclone's PowerBoost, are designed to charge during those stops.

If runtime matters in a large home, choose vacuum then mop, so the robot vacuums every room first and mops in a second stint. Clean-water tank size matters too: a 3 litre dock tank, as on the Eufy X10 Pro Omni, is enough for a large floor area before you need to refill it.

Frequently asked questions

What robot vacuum has the longest runtime? On current UK listings, the Ecovacs N20e Plus quotes 300 minutes. Real runs are shorter on carpet or high power.

How long does a robot vacuum take to charge? Typically a few hours from empty. Some docks charge faster; the Eufy S1 Pro station claims 20% faster charging.

Should I leave my robot on the dock? Yes. It is designed to stay docked and manages its own charging.

Why does my robot's battery not last as long as it used to? Lithium batteries wear with use. Clean the brushes and filters first, then consider a new battery.