It sounded too good to be true: a low energy use, smart pool cleaner. It is too good to be true! Maytronics, well known for their robotic pool cleaners isn't perfect. Look at all of the problems users have had with their Maytronics cleaners on this forum. The common problem: "my unit turns on for a couple of minutes the pump spins and then the tracks move....but then the unit stops!
Welcome to the world of digital electronics in a difficult environment-a swimming pool with it's chemicals, stairs, walls, UL approval for 120V AC wet application.
The nice thing about a working robot is that it is very energy efficient and vastly superior to auxiliary pump driven cleaners that pick up some leaves and large particles of stuff. The filter bags with the use of a fairly strong suction using a DC motor do a very good job of cleaning the pool.
The bad thing about a robotic pool cleaner is their expected life suggested by the manufacturers warranties, 3 years at most but typically 1-2years. This is pretty good if you use the pool cleaner every day or two but, if like me, you already have a pump driven pool sweep, and only use the unit every few weeks or even months to clean up major events of weather, the robot can be a relatively expensive option. My unit failed after 50-100 cycles resulting in a cost of $7-$20 per cycle (typically 3 hours). Typical unit cost of $700-$1000.
The most common failure appears to be water leakage into the unit either through the O-ring motor box seal OR stress cracks in the plastic housing surrounding the track drive motor shaft(s).
The electronics used in the Maytronics units is very interesting. They use an Atmel microcontroller to drive the motors with a PWM (pulse width modulation) drive allowing full motor speed control for both the fan(pump) motor and the track motor. The initialization phase drives each motor while measuring it's operating current to make sure the motors are both operating properly. There even appears to be a failsafe mechanism for turning off the remote power supply in some cases. The electronics have the ability to overload the external power supply essentially giving it a signal to shut down using only the increase in current drawn from the power supply. This technique eliminates the need for extra communication lines back to the external power supply unit and probably help to meet a UL requirement.
The point to my article is that if you use the robots a lot, then they are a good solution but if you use these robots only periodically then you might question if they are worth the expense. You can run your pool pump and auxiliary pool cleaning device for much less than the $7-$20/cycle it will cost if you only get 50-100 cycles out of your robotic pool cleaner.