A corded robot draws power through a floating cable from a supply on the deck, for as long as the cycle lasts. A cordless robot carries a battery, so its rating is about how much surface one charge covers. Most of the choice follows from that.
How each is rated
Maytronics rates its corded Dolphins by pool length: 33 ft for the Nautilus CC, 50 ft for the CC Pro and CC Supreme. The length is about the cable reaching the far end and the robot covering the floor in its cycle.
Aiper, Beatbot and Wybot rate their cordless robots by area. The Aiper Scuba S1 is rated for 1,600 sq ft, the Wybot C2 for 2,152 sq ft and the Beatbot Sora 30 for 3,229 sq ft. If the robot climbs walls, the walls count: a 32 by 16 ft pool that runs 3.5 to 6 ft deep has 512 sq ft of floor and about 970 sq ft with the walls. The pool size calculator works this out for your pool.
Runtime comes with a mode
Cordless makers give runtimes by mode, and one robot can carry several figures. Aiper gives the Scuba S1 up to 180 minutes in standard mode and longer figures for its Eco mode. Wybot’s 180 minutes for the C2 is its Eco figure. Beatbot gives the Sora 30 up to 5 hours on the floor alone and 4.5 hours covering floor, walls and waterline. Compare robots in the same mode, and use the one that cleans the surfaces you need.
Maytronics publishes no battery size, runtime or charge time for its cordless LIBERTY line. It gives cycle lengths instead: 2.5 hours by default on the LIBERTY 200.
Charging and the outlet
Corded robots plug their power supply into a GFCI-protected outlet, with the supply kept back from the water as the manual directs. Cordless robots move that question to the charger. Maytronics’ quick guide for the Niya Sonar 20, a cordless floor cleaner, asks for a 30 mA GFCI and puts the charger at least 12 ft from the pool edge. Charge times run from about 3 hours (Wybot C2) to about 4.5 hours (Beatbot Sora 30).
A cordless robot also has to come out of the water to charge. Several have a retrieval feature: Dolphin’s Click-Up surfaces the LIBERTY at the end of a cycle, and the Polaris Freedom’s listing describes it climbing to the waterline for pickup.
Where each fits
Corded suits a pool cleaned on a schedule by a timer, with an outlet near the deck. There is no battery to wear out, and the Dolphin weekly timers run without anyone lifting the robot out between cycles. Cables twist without a swivel; the CC Plus, CC Pro and CC Supreme have one, the base Nautilus CC does not.
Cordless suits a pool without a handy outlet, or a deck where a cable is in the way. Expect to lift the robot out to charge, and to compare runtimes in the same mode.
Both kinds are compared on the inground and above-ground pages.