US Patent 6842931 Submersible pool cleaner with integral rechargeable battery

A submersible robotic pool cleaner is provided with an integral sealed rechargeable battery and an inductive charging assembly, a first portion of which is mounted in the pool cleaner housing and during the charging, receives a second separate portion that is connected by a cable to a conventional power source. The pump motor drive shaft is treated with a specialized anti-friction lubricant composition to minimize frictional energy losses where the shaft contacts the seal(s) and any shaft bearing(s), to maximize efficiency and minimize the power consumption of the pump motor assembly and permit the pool cleaner to completely traverse the surfaces to be cleaned within the fully-charged power capacity of the battery.