Digging Into Thrift Store Neato XV-21

Of course, I didn’t buy a nonfunctional robot vacuum from a thrift store just to admire how clean it is. I bought it to see if it can be brought back to life. So out comes the screwdriver set and it’s time to dig into those non user serviceable parts inside. Fortunately Neato didn’t feel the need to complicate this effort with “security” bits that would only hamper resourceful hackers by a few seconds – they were straightforward Philips head screws. I had expected fine pitched machine screws, but they were actually coarse pitched screws that self-tap into plastic. This limits the number of times we can assemble and disassemble this vacuum before the screws become too loose to hold themselves in place, but that’s a concern for the future.

Neato XV-21 with bottom panels removed

There are three easily accessible panels. Two rectangular battery compartment doors each held by two screws, and a large semicircular panel held in place by four screws.

Underneath the semicircular panel is a large centrifugal (squirrel-cage) fan responsible for creating the suction that gives vacuum cleaner their name and purpose. The filter sitting in the back end of the dust bin is visible. Air would move past the filter, through the fan, and exhaust out the grating at the back. It would not have been surprising to find a coat of fine dust that made their way past the filter, but the fan compartment is pristine. Either the filter is far more capable than I give it credit for, or this vacuum was indeed barely used.

Neato XV-21 wheel encoder

On either side of the fan are motor gearbox assemblies for driving the vacuum around. The motor appears to be a commodity DC brushed motor, but it does have some sort of encoder mounted to its back. Looking at the circuit board we saw a single sensor, indicating this encoder can sense motor movement but not its direction: a full quadrature encoder would have had two sensors on the board.

Also visible behind the robot’s left wheel (right side of top picture) are wiring for external connectors:

  • Mini-USB for serial data, which would be extremely interesting if I could get the vacuum powered up.
  • Barrel jack for a charging adapter I don’t have.
  • Two thick metal wires to make contact with a Neato charging dock, which I also don’t have.

Given that the official chargers were absent from this thrift store purchase, the next step is to remove these two battery packs and see what we can do with them.

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