Tuesday, February 12, 2008

It's Alive, It's Alive: Replacing a Dead Roomba Battery

Recently, after more than a year of good service, our Roomba robot vacuum cleaner stopped working properly. It would reverse out of its dock at the scheduled cleaning time, then immediately play the "I'm tired" music and return to its dock. This behavior indicated to me that the battery pack wasn't holding its charge, and a search of the internet revealed that many Roomba and Scooba owners were experiencing the same problem. Apparently, iRobot was cutting corners with the OEM batteries.

The internet also showed us that the battery pack was composed of 12 sub-C-sized 3000-mA-hr NiMH batteries and a thermistor wired to 3 connectors. I thought about buying some higher-capacity batteries and rebuilding the pack using the existing temperature sensor, but then I came across this item for sale. It offered slightly more capacity than the stock batteries and was cheaper to buy than I would pay for the same batteries, retail, plus it included a new thermistor. Thus, I decided to purchase it. Then I saw this pack, which offers 40% more capacity, and I knew I had to get it.

The new pack arrived last night, and we set about modding the Roomba. The major problems with this operation were unscrewing the odd, triangular (not Tri-Wing) screws that hold the battery case on---this ground-down Tri-Wing screwdriver wasn't a perfect fit---and pulling apart the glued-shut case. After Alison took care of de-casing the battery, I set about soldering the connectors onto the new pack while watching Top Gear. (I guess I should have said "whilst" watching Top Gear.) We charged the robot up overnight---the new pack takes 1.4 times as long to charge---and this morning, the Roomba vacuumed the floors without hesitation.

So, not only have we fixed the instant-fatigue syndrome, but the robot can now clean for 40% longer than it could when new. I'd call that a successful repair.

1 comment:

  1. Anonymous12:34 AM

    Really good information and the battery site is brilliant thank-you

    Chris in Queensland (Great Barrier Reef eat your hearts out:) )