Pool Robot Winter Storage: Battery, Temperature, and Drainage

Four things have to be true before the box closes

Off season storage is four separate jobs, and makers document them at very different levels of detail. The robot has to come out of the water clean and dry with its filter emptied. Whatever water it holds internally has to come out. Its battery has to sit at whatever state of charge its maker names, topped up on whatever cadence its maker names. And the space it sits in has to stay inside the ambient temperature range its maker names, if its maker names one.

That last clause carries more weight than it should have to. Not one of the four brands quoted here prints a storage temperature as a spec row on any model we publish a page for. Every numeric storage range below comes from a blog post or a support page, while the spec tables themselves publish only operating and charging environment temperatures, which describe the machine at work rather than in a box. Treat all of it as manufacturer guidance rather than tested results; we have not hardware tested any of these machines.

Storage temperature, brand by brand

Start with what the spec tables do not say. Neither Wybot page carries a storage temperature row at all. The Wybot C2 Vision and Wybot S2 Solar tables each publish an Operating Temperature of 41 to 95 degrees F in the General block, a Charging Environment Temperature of 41 to 95 degrees F in the Battery block, and a second Operating Temperature of 50 to 95 degrees F also in the Battery block, under a disclaimer that the block was tested in a laboratory environment and should be used for reference only. Two things follow. Storage is not a spec table field for either machine, so anyone quoting one of those rows as a storage range is quoting an operating range. And the two operating figures on the same page, 41 to 95 in one block and 50 to 95 in the other, do not agree with each other, which is a contradiction inside a single Wybot table rather than between two documents.

Wybot's winter maintenance blog post carries the only Wybot storage figure that exists, an ambient range of 41 to 113 degrees F (5 to 45 degrees C), whose ceiling sits 18 degrees above the operating ceiling on its own store's spec table. Maytronics publishes that same 41 to 113 degrees F (5 to 45 degrees C) range as the best storage temperatures in its Dolphin winter storage article, also a blog post. Beatbot's off season guidance is qualitative: store the cleaner indoors where temperatures stay above freezing, out of direct sun, away from damp basements and unheated sheds, with no ceiling or floor given. Aiper's cold season care page says to box and store the device in a cool, well ventilated area, and its Scuba S1 battery care article says room temperature.

• Wybot C2 Vision: no storage temperature row; operating 41 to 95 degrees F in the General block and 50 to 95 degrees F in the Battery block, laboratory basis.
• Wybot S2 Solar: no storage temperature row either; the same three rows, charging environment 41 to 95 degrees F alongside the two operating figures.
• Wybot winter maintenance blog post: ambient 41 to 113 degrees F (5 to 45 degrees C), above its own spec table's operating ceiling.
• Maytronics Dolphin winter storage article: best storage temperatures 41 to 113 degrees F (5 to 45 degrees C).
• Beatbot: indoors, above freezing, out of direct sun, not a damp basement or unheated shed; no numeric range published.
• Aiper: a cool, well ventilated area, and room temperature on its Scuba S1 battery article; no numeric range published.

Storage charge level, where the brands flatly disagree

This is the instruction where following the wrong brand's advice actually costs something, because Aiper and Wybot say opposite things. Aiper's cold season care page instructs owners to charge the device every two months to 40 to 60 percent battery capacity to maintain battery health, and to fully charge it only when it is about to go back in the pool. Wybot's winter maintenance article instructs owners to make sure the battery is fully charged before storing the cleaner, and to charge it every three months.

Aiper is also not internally consistent. Its Scuba S1 battery care article, a separate page on the same domain, says to maintain 50 to 60 percent charge at room temperature for off season storage and to avoid continuous charging beyond 24 hours. That is a different band from the 40 to 60 percent on the cold season care page. Neither figure appears in the Aiper Scuba S1 or Scuba S1 Pro spec table, so the datasheet offers no tie breaker.

Beatbot names no number at all. Its guidance is to set the battery to the charge level your manufacturer recommends for storage, not empty and not left at a random level, and to check the unit's manual for the exact storage charge. For an owner of a Beatbot AquaSense 2, AquaSense 2 Pro or AquaSense 2 Ultra, that is a pointer without a published destination on the Beatbot pages we could reach.

Maytronics comes at the same problem from the other end and describes what happens when a battery robot sits untouched. Its article states that a robot unused for 21 days or more may automatically enter sleep mode, that connecting the charger wakes it, and that it should be fully charged before it is used again.

• Aiper cold season care page: charge every two months to 40 to 60 percent capacity.
• Aiper Scuba S1 battery article: maintain 50 to 60 percent at room temperature; avoid continuous charging beyond 24 hours.
• Wybot: store fully charged, then recharge every three months.
• Beatbot: defers to the unit's manual; no storage percentage published on its off season article.
• Maytronics: 21 days or more idle can trigger sleep mode; connect the charger to wake it; full charge before reuse.

Drainage and drying: the step nobody disagrees about

Every brand here says the same thing in different words. Nothing goes into a box wet, and nothing goes into a box with a loaded filter. Aiper's published sequence is to power off, disconnect the charger, clean residual dirt from the top and bottom shells, wheels, roller brushes and charging port, wipe the unit dry with a paper towel or soft cloth, then box it. Wybot's is to power off completely, thoroughly dry both the cleaner and the filter basket to prevent moisture damage, and avoid squeezing the unit in storage. Beatbot's is to take the cleaner out as soon as the cycle ends, empty and rinse the filters before storing, and let every part air dry so no moisture is sealed inside.

Trapped water is a design consideration rather than a housekeeping detail, and two models we track address it on the spec sheet. Beatbot publishes that the AquaSense 2 Pro returns and parks on the water surface and releases its internal water so it floats lighter for pickup. Aiper publishes a rapid water release on the Scuba SE that drains 80 percent of stored water in 15 seconds. Neither claim carries a stated measurement basis, and both are the maker's own.

A corded cleaner adds two steps a cordless one does not have. Maytronics instructs owners to check the manual for the drainage valve or plug and remove the water completely, to coil the cable without kinks so it does not tangle or get damaged in storage, and to store the unit upright on a caddy, which also keeps rodents and insects out of the shell. The corded model we publish a page for, the Polaris EPIC 8642 iQ, runs on a published 60 ft cable with a tangle reducing swivel, and a properly coiled cable is the difference between a working cable and a kinked one in spring.

The checklist

Order matters here, because a step done out of sequence undoes the one before it. Charging a wet robot, or drying one that still holds a litre of water in the chassis, wastes the effort. This sequence merges what all four makers publish, with the brand specific numbers marked where they differ.

• Run a final full cycle while the water is still balanced and circulating, then lift the robot out as soon as the cycle ends.
• Empty and rinse the filter basket. Nothing goes into storage with debris in it.
• Release or drain the internal water, using the model's own water release if it has one, or the drainage valve or plug named in the manual for a corded unit.
• Power the unit off and disconnect it from the charger or power supply.
• Dry the shell, wheels, brushes and charging contacts until nothing is damp, by cloth or by air.
• Set the battery to the level your maker names: 40 to 60 percent for Aiper on its cold season care page, fully charged for Wybot, the manual's figure for Beatbot.
• Coil a corded unit's cable without kinks and store it upright, on a caddy if you have one.
• Store indoors, dry, out of direct sun and away from frost and heat sources, inside whatever ambient range your maker publishes.
• Put the recharge on a calendar: every two months for Aiper, every three months for Wybot.
• Before the first spring run, fully charge the unit. A Dolphin that has slept 21 days or more needs the charger connected to wake it first.

What none of these documents settle

Three gaps are worth naming, because they set how much weight this guidance can carry. First, none of it is a specification. Every storage charge level, recharge cadence and storage temperature quoted above lives on a marketing blog or a support page that gets revised without version numbers or dates. Not one manufacturer in this set treats storage temperature as a spec table row; the tables carry operating and charging environment ranges instead, which describe the machine at work. A blog instruction is a manufacturer statement, which counts for something, but it is not the same artifact as a datasheet line.

Second, the brands disagree and one brand disagrees with itself. Store at 40 to 60 percent (Aiper) and store fully charged (Wybot) cannot both be ideal for the same lithium chemistry, and Aiper's own two pages give 40 to 60 percent and 50 to 60 percent. Where a maker's instruction is specific to its own battery management system, follow that maker rather than the general advice, and where one maker gives you two bands, the overlap is the conservative read, which here is 50 to 60 percent.

Third, none of these documents publishes a cycle life figure or a storage related capacity loss figure for the models we track, so there is no published basis for pricing what a badly stored winter costs. We record that as not published rather than estimate it. For the specs that are published, see how to choose a robot pool cleaner, and for the runtime and charge time figures this whole exercise exists to protect, see robot pool cleaner runtime and battery.

One note on the Dolphin guidance quoted above. We publish no Maytronics model pages, because Maytronics does not publish a floating cable length on the US datasheets for the three Dolphins we researched, and cable length is the spec that defines a corded cleaner's working envelope, as cordless vs corded robot pool cleaners works through. That is a gap in its purchase specs, not in its storage guidance, so what Maytronics publishes about winter storage stands on its own.