The Neato XV-21 I found at a thrift store has bee joined by a XV-12 found by [Emily]. Both Neato robot vacuums found at thrift stores have degraded batteries. This was not a surprise as robot vacuums work their battery packs hard. Not just frequent charge and discharge cycles, but with a heavy power draw under use to run vacuum motors. This means both of these vacuums were retired by their previous owners when the battery no longer hold enough charge to perform its duties.

Neato XV-12 battery unhappy

Fortunately, this common failure also meant there's a robust aftermarket for replacement batteries. Curiously, the economics of the markets are such that whole replacement packs can be ordered online for less than ordering individual cells and rebuilding the packs myself.

With previous experiments, I have gained confidence I can verify functionality of individual components using test mode accessible via USB port. And since this XV-12 was found with an official Neato charging dock, it's time to install replacement batteries and test the full system.

The replacement batteries claim a capacity of 4000mAh which, on paper, is an increase from the original battery's label capacity of 3800mAh. However, battery manufacturers play pretty loosely with these ratings so I expect the difference of 200mAh to be fairly insignificant in practice. When I took apart the original pack, I saw a thermister for monitoring temperature, an overcurrent protection fuse, and an overheat fuse. I assume the replacement pack has a thermister because the Neato computer can read it, but there's no immediate way to tell if the overcurrent or overheat protection also exists on the new pack.

Neato XV-12 batteries old and new

With new battery packs installed, it's time to put the robot up against the charging dock and verify the charging system works as expected. But before we do that, let's take a closer look at this charging dock.