Executive summary: It’s not fast, it’s not smart, and it needs your help … but it does clean the carpets.
In particular: The three inch high “kick space” under the front of typical cabinets forms a nasty Roomba trap, especially if the space extends more than two inches behind the front of the cabinet. This seriously reduces the usefulness of the Roomba for sweeping the kitchen floor.
You need to learn how to use a Roomba. Here’s an example of what I mean.
Suppose you are vacuuming the dining room. You need to vacuum under each of the chairs.
A slightly cleverer solution is to flip the chairs up onto the table, as they sometimes do at the pizzeria at closing time. This allows nearly-unobstructed sweeping, and doesn’t require moving the chairs very far.
A trickier solution involves two steps: First, leave the chairs where they are and let the Roomba clean around them. Then, move each chair a short distance, and turn the Roomba loose again. This means that most parts of the room will be cleaned twice, while areas near the chairs will only be cleaned once … but there’s nothing wrong with that. My objective is to minimize the amount of work I have to do, and if the Roomba has to do a little extra work, so be it.
The batteries can be recharged, but only a few hundred times. Eventually the battery becomes worn-out and useless. Then you have to buy a new battery pack.
The Roomba is remarkably stupid about this. Sometimes – not always – here’s what happens: When it is on the charger, it thinks it is fully charged, but as soon as you take it off the charger it thinks the battery is empty. Another symptom of a messed-up battery is that sometimes – not always – leaving it on the charger overnight is less helpful then using it immediately after charging. I’m not sure I understand this, but it may be related to the Roobma’s non-understanding of open/loaded issue discussed below.
Typically when the battery fails, almost all of the cells within the battery are still good; only one or two cells have died.
Therefore, keep the old battery pack whenever you buy a new one. The reason is that when the second one fails, you can repair it by clipping out the bad cell and replacing it with a good one from the other pack. This requires some soldering skills.
You usually cannot detect a bad cell by looking at its open-circuit voltage. Instead, you should load the battery pack using a 50 Ω resistor with a 5 W (or better) power rating, and look at the cell voltages under load. To say the same thing another way, typically the cell fails by developing an unacceptably large internal resistance.
Note: On the cover of the battery pack, the screws may have a funny three-cornered socket head. You could buy a special tool for dealing with these, but it is just as easy to make one. One solution is to start with a #10 machine screw and put a triangular tip on it using a file or a grinding wheel.
If the Roomba detects a problem, it will stop and play a “song” consisting of the two-tone “uh-oh” prefix followed by a number of beeps. The meaning of the beeps is: