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Mini Cooper Confidential

Roomba Battery Woes

I've written about the robotic cleaning appliances from i-Robot before ( here, here, and here) but this time I'm writing with an important tip for Roomba and Scooba owners.

Do not leave your robot uncharged, ever.

Lately, whenever I left town, I'd unplug the Roomba's charging unit. When you do this the battery eventually drains, and then it sits uncharged until you plug it back in again, right?


When you do this you destroy the battery and it won't ever hold a charge again.

iRobot tells you this, (here and here) and woe unto you who ignore (or forget) this advice. I can show you the receipt for my $50 replacement battery if you want proof. (I tried resetting the Roomba's power manager to no avail, if you find yourself in this situation, give it a try before replacing the battery.)

If you won't be using your Robot for a while, the correct thing to do is to completely remove the battery, per one of the articles linked to above.

Ugh. But I still loves our Roombas. And the new Scooba is working out well so far. (More about the Scooba after I've used it more.)



Thanks for putting this article together, complete with the iRobot links. It's very helpful!


Thanks for the information and links. I just tried the power cycle trick as listed in your links.

Thanks again.


Yes this is true. We left it unplugged for 2 weeks, and now it can only managed 15 mins. It was only 6 months old. Rip off.

Gordon Meyer

You should call iRobot tech support for warranty service.

Peggy-Gail Forehand

I left mine plugged in and that also destroyed the battery.


How long should a roomba battery run before it is out of juice? Mine only runs 30-40 min at a time.

Tom Burnet

You can recharge a "dead" Roomba battery as long as there are no shorted or reversed cells. Even then, it may still be possible to recover the majority of its capacity. The Roomba uses 12 NiCad cells in series (nominal 14.4 Vdc). Remove the battery and turn it over. There are 3 slots on the bottom side of the longest extension arm of the case. The slot closest to the pack is negative, the one furthest is positive. I use a DC power supply and set the output voltage at 17.5 and current at 220 maDC and connect the output to the slots indicated above. To clear a short or start a reversed cell back in the right direction, increase the output current to 1000 maDC and monitor the voltage. It should ramp up fairly quick. When it reaches 16, you can be pretty sure it's going well so back down to 220 maDC. That's the optimum rate for 24-48 hours. Check on the battery from time to time to make sure the battery is not hot (a little warm is OK). After 24 hours or so, reinstall in the Roomba and let it dock on it's homebase. It make take another 24 hours until the charge light goes from blinking red to solid green, but the battery will recover. NiCad batteries are different from lead batteries. NiCads store the charge in the plates, not the electrolyte. Therefore they can be stored uncharged. In fact, OEMs receive NiCads in a discharged state. NiCads are also different from NiMh. The NiMh is intended to be used immediately after charge...they don't store or trickle worth a flip! This comes from 45 years of designing battery operated commercial devices...


Ohh, I wish I would have read this before...I could not understand how something only 1 year old could have such a bad battery, but now I know since I did let it uncharged for a about 2 weeks. The batteries are so expensive!!! And, I have not used my Scooba in months (and it's not in the charger), so I can expect to have to buy a new battery for that one too...:( Thanks for the information!!

k wayne

This site has been helpful so maybe you can give feedback on the problem I am having with my roomba. I unplugged the roomba, it discharged and would not hold a full charge so I bought another battery from Irobot. It worked well for about 2 weeks then would not hold a charge. The more I reset the battery the worse it got until it would not charge at all. I ran the roomba with the new battery every couple of days per instructions so it should have been fine.

Irobot sent me another battery and it is doing the same thing. The specific symtoms are the roomba will be fully charged on the docking station, but will only run for less than 1 minute then the battery light turns red and the roomba stops. If I turn off the roomba, remove and reinstall the battery, the battery light will turn green, the roomba will run less than a minute, stop with a red battery light. If I remove the battery and reinstall it, the battery light will turn green again. What is wrong with this roomba. I have cleaned it, all parts appear normal, wheels turn etc. Do you have any idea what is wrong with my roomba?


Is correct that the dock voltage is 4.9Vdc?? I direct connect the plug into my roomba, it has 22vdc, when the current travel to the pin or plug it have 4.9Vdc in the battery terminal. The problem that I have is the roomba don’t charge up.

Omar from Puerto Rico

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