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How long does a Roomba take to charge?

Alvina Wang/BestReviews

Everything you need to know about Roomba charging times

Roomba robot vacuums run on internal batteries. They don’t rely on cord connectivity as they explore the spaces beneath your dining table and behind your couch. Like all batteries, however, they need recharging. How long does it take for a Roomba to charge?

The answer, for most Roomba models, is two hours. But the actual time depends on how much charge is left, the health of the battery and the Roomba model you have.

How long does it take to charge a Roomba?

It generally takes around two hours to fully recharge a Roomba battery. This applies to most Roomba models, including those in the entry-level 600 series, the mid-range i series and the high-end j and s series. 

Most Roombas run on lithium-ion (Li-ion) batteries. That said, some Roombas — like those in the Roomba 400/Discovery series — are powered by nickel metal hydride (NiMH) batteries. These batteries vary in size, shape and capacity. 

For example, Roomba i1, i3, i6, i7 and the e series use an 1,800 mAH (milliamp hour) Li-ion battery, while Roomba i4, i8 and j7 use a 2,210 mAH Li-ion battery, providing those models with longer battery life or more power to run their features. The Roomba s9 and its variants use a 3,300 mAH battery to sustain its powerful suction and alternative chassis and brushroll design.

Actual charging time depends on how much charge is left in the battery, how old the battery is and sometimes the ambient temperature of the room. If a battery is only partially drained, it recharges to full faster. But if the Roomba has been running a lot, its battery may be almost depleted. In this case, it may take a little over two hours to fully recharge. A Roomba that’s very low on power may show a flashing or solid red battery icon or light ring. If so, it won’t have the power to make it back to its charging dock.

One of the most common problems with recharging a Roomba stems from having dirty charging contacts. The metal strips on the bottom of a Roomba connect with metal points on the charging dock in order to take in power. If these strips are dirty, grimy or obstructed, charging may be slow, or it may not work at all. 

It’s important to keep both pairs of charging contacts — those on the Roomba and those on the dock — as clean as possible.

Roombas try to return to their docks if they sense their batteries running low. Models in the i and s series can recharge for about one hour and 25 minutes and then resume the cleaning job they were on when they ran low. Some models, such as the Roomba s9, can remember where they already cleaned and charge just long enough to finish the uncleaned area.

Roomba battery life

Different Roomba series families have different minimum runtimes.

According to iRobot, the maker of Roombas, you should expect the following minimum runtimes for your Roomba:

  • The e Series should run for at least one hour and 30 minutes.
  • The i, j, s and 900 series should run for at least one hour and 15 minutes.
  • The 400 to 800 series should run for at least one hour.

Actual performance depends on how dirty your floors are, how much carpet you have (Roombas work harder on carpet, using up more battery power), if the rollers or airflow get obstructed and if the Roomba faces a lot of obstacles.

If a Roomba isn’t reaching the minimum runtime listed above, there may be something wrong with the battery. Roomba batteries last two to three years with typical use. After that, they may start to lose charge or not recharge effectively. When this happens, it’s time to get a new battery. iRobot recommends only genuine Roomba replacement batteries.

Troubleshooting common charging issues

If you run into charging problems with your Roomba, it may give you an error number. Here’s what to do when you get an error code.

  • Errors 1, 8 – 11 and 17 mean the battery is not detected. The Roomba can’t detect or communicate with its battery. This may be due to a breakdown or the fact that it’s not a recognized battery. Install a new genuine Roomba battery.
  • Errors 2 and 3 signify possible water damage. Check for damage and try again.
  • Errors 4, 5 and 21 signify low current or an inability to charge. Clean the charging contacts on the Roomba and on the dock.
  • Errors 6 and 7 mean the battery is too warm or too cold. Charge your Roomba in a comfortable room away from direct sunlight.
  • Error 19 denotes a charging timeout. Remove the battery, put it back in and clean the charging contacts.
  • Error 20 points to a battery fault. Remove the battery, wait for 15 minutes and then reinstall it. If the error persists, replace the battery.

For a full list of errors and solutions, see our article How to tell if a Roomba is charging.


How do I know my Roomba is charging?

It can be hard sometimes to know if your Roomba is charging. When a Roomba returns to its dock, its battery icon or light ring indicator glows for around 60 seconds and then turns off to save energy.

You can check if it’s charging by tapping the “Clean” button while it’s on its dock. A single tap on the “Clean” button of a docked Roomba reawakens its battery icon or light ring. The color and behavior of the icon or light ring (solid, pulsing or blinking) lets you know if it’s charging or fully charged.

Should I leave my Roomba on the charger all the time?

Yes, you should leave your Roomba on its charger whenever it’s not in use. iRobot recommends Roombas return to their charging docks after every job and stay docked until their next job. This applies to Roombas with Li-ion batteries and Roombas with NiMH batteries.

The only exception is if you don’t plan to use your Roomba for a long period of time, say a month or more. In this case, iRobot recommends you put a Roomba with a Li-ion battery into what they call “ship mode” by holding down the “Home” button for 10 seconds. If your Roomba has a NiMH battery and you want to store it, it’s recommended to charge the battery to full and then remove it physically from the Roomba for storage.

How can I maximize my Roomba’s battery power?

To maximize your Roomba’s battery power, clean its filters, brushes and internal cleaning path regularly. Clogged filters, tangled brushes and obstructions in the air flow force your Roomba to work harder and use up more juice.

It’s also recommended that you charge your Roomba at a comfortable room temperature. Rooms that are too hot or cold affect how well the battery recharges. Avoid charging the Roomba in direct sunlight, as that may cause the unit to heat up.

Frequent use helps keep a Roomba’s battery healthy, as does fully charging it at least once every six months.

A clean, cool Roomba charges best

A Roomba can recharge in about two hours — sometimes a little less, sometimes a little more. Remember that you don’t have to do anything to it while it recharges. If it had to recharge in the middle of a job, it may take less than two hours to get back up and running. Keep your Roomba clean, keep it at room temperature and use it frequently for the best and most convenient user experience.

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Jmar Gambol writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.

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