Dreaded circle dance


| My Roomba vacuum cleaner, doing business as "Fiona," is nearly three years old, having been purchased in May of 2014.

Actually, that's not true: the original Fiona started having fits the following year (Fiona ist kaput) while trying to dock on the charging station, and was replaced by iRobot since it was still under warranty, so that makes this generation of Fiona about two years old.

In recent months she has become quite flaky, failing to return to the docking station when her battery runs down and shutting off mid-clean from simple exhaustion. And, the length of time she would clean was getting shorter and shorter. Instead of an hour or an hour-and-a-half of continuous cleaning, she would expire after, say, half an hour. At other times she would strand herself on a dark-colored runner behind the island in the kitchen.

Friends Jim and Angela suggested that perhaps I should replace the battery, which made sense since although iRobot replaced the machine, I had to transfer the original battery into the replacement, making the battery nearly three years old. I had been reluctant to take that step, however, since my previous investigation of replacement batteries always led to an enormous price tag. But Angela assured me I could get a replacement from Amazon for $25, and so it turned out to be.

The replacement battery arrived Saturday and I set about replacing it.

Remove screws to expose the battery
Four screws must be removed to expose the battery
Original battery pack, top. The flaps of green tape are to make it easy to remove the battery pack.

Replacing the battery was no big deal. After all, when Fiona was replaced I had to transfer the original battery into the replacement, so this was familiar territory.

But wait! There are four "cliff-sensors" around the front of the Roomba. These enable it to detect when it is about to drive off a cliff (like a stair step). Or, in the case of Angela's "Tony," keep it from running off the edge of the big ottoman she would put him on just for fun. And, looking at them, I noticed that one of them had a lot of dirt inside the sensor where it is not supposed to be.

Dust-filled cliff-sensor
Dust-filled cliff sensor
A clear cliff-sensor
A clear one
Dirty cliff sensor
Some dust inside
Dirty cliff sensor
Some dust inside

Seeing that one of the sensors was absolutely filled with dust, I began to think that that was perhaps the reason for the weird behavior.

I hoped that I could maybe just tug on it and pull it out, blow out the dust, and put it back in. No such luck. It wouldn't budge. Then it occurred to me that if I took off the bumper around the front half of Roomba I could see how the sensors were attached and have better luck. I proceeded to remove the eight screws that hold the bumper in place.

Remove 8 screws to detach the bumper
Eight screws attach the bumper

As I unscrewed one screw after another my courage began to wane. The bumper began to "pop out" in places and I began to fear that I would never be able to get it back together again. So, I tightened all the screws back up.

The next morning when Fiona started her normal cleaning, she began to do the dreaded "circle dance" in which she appears to back up and go in circles. After a bit she announces, "Error 9. Tap Roomba's bumper to clean." This means, according to the manual, "Briskly tape Roomba's bumper 10-20 times to dislodge any debris that may be trapped under the bumper."

Sometimes she would, in fact, start out on a cleaning sortie, but as soon as she got to any kind of obstacle would resume the circle dance.

When in doubt, Google. Searching for "Roomba circle dance" or "Roomba error 9" returns a bonanza of articles and videos how to fix this error. I quickly discerned that most of them called for replacing the offending sensor and then using a soldering iron on wires and circuitry. Although I'm quite brave about plunging in ("Fools enter etc"), I draw the line at soldering wires and circuit boards. At that point I began researching replacements; another robot vacuum called Neato seems promising, and I like that it works more like a Zamboni on an ice rink rather than a crazed pinball. But still, the price, the price...

However, in the process I had become reassured that taking out those eight screws and removing the bumper would not end in disaster, so I got out the screwdriver and began. It was at that point that I noticed one end of the bumper had not been properly hooked over a bracket when I re-assembled it the first time. I corrected that and decided to quit while I was ahead.

Voila! The next morning Fiona went cheerily about her duties and ran for over an hour. She still didn't make it back to the charging station. It seems to be a design flaw that when the battery starts to run down she does not actively seek out the charging station. It seems that she only docks if her random careening around happens to take her past the station.

Last updated on Apr 13, 2018



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