Tests, tools & research
Sex toy battery life: why the advertised run time is the best case
A run time is only meaningful alongside the setting it was measured at and the age of the cell. Both are almost always left out, which is why a toy advertised at two hours can stop in twenty minutes.
The number on the box is the most favorable number available
A motor draws current roughly in proportion to how hard it is working, so the lowest continuous setting can run for several times as long as the highest. A manufacturer with one figure to print has an obvious incentive, and nothing obliges them to say which setting it refers to. The figure is rarely a lie. It is a best case presented without its conditions.
Two further conditions are left out just as often. A run time is measured on a cell that has never been cycled, and a lithium cell loses capacity as it ages, faster if it is stored hot or left empty for months. And it is measured free running, with nothing pressed against the head, which is not how the toy is used: a motor meeting resistance draws more current, so the same setting empties the same cell sooner in use than on a bench.
This is why the useful question is not how long the toy runs, but how long it runs at the setting you would actually choose, after a year of charging.
What a run time figure must state to be worth reading
- The setting. Lowest continuous, highest continuous, or a named pattern. Without it the number means nothing, and patterns complicate matters further because a pulse that spends half its cycle idle will outlast a constant output at the same nominal level.
- Loaded or free running. A motor under pressure draws more. A figure measured in open air is the longest one obtainable.
- The state of the cell. New, or after a stated number of cycles. The second is far more useful and essentially never published.
- What counts as the end. Stopped entirely, or dropped below usable output. Many toys fade before they cut out, and the gap between the two can be large.
- The charge time and the interface. A long run time matters less if a full charge takes four hours, and it matters a great deal whether the port is USB-C, a proprietary magnetic puck, or the discontinued connector you can no longer buy.
The cell is usually the product lifespan
Almost nothing in this category has a replaceable cell. It is sealed inside silicone for waterproofing, which is a sound engineering reason, and the consequence is that the toy lives exactly as long as its battery. When the cell will no longer hold a charge the whole object is finished, however good the motor and the shell still are.
That makes charging behavior part of the purchase rather than a detail. A cell kept near empty for long periods, or charged in a hot room, or left on the charger continuously in a product whose charge controller does not stop, degrades faster than one topped up occasionally and stored around half full.
It also makes the charging interface a durability question. A proprietary puck is one lost accessory away from a dead toy, and a brand that has stopped selling the puck has retired the product whether it says so or not. USB-C on the toy itself is the arrangement that survives longest, and waterproofing is why so few use it.
The method results on this page will follow
Charge to the device full indication, then rest
Charged until the toy reports full, then left off the charger for a stated interval before the run starts, so a surface charge does not inflate the result.
Timed discharge at both ends of the range
Lowest continuous setting and highest continuous setting, each run to the end, with the ambient temperature recorded. Two figures rather than one, because the pair describes the usable range and a single figure never does.
A second pass under load
The same two settings with a stated force applied through a stated compliant material. The difference between free running and loaded is published, not averaged away.
The end point defined and recorded
Both moments noted: when output becomes visibly weaker and when the motor stops. A toy that fades for fifteen minutes is reported that way.
Charge time measured the same way
From the stopped state to the full indication, on a stated supply, with the port type recorded. A run time without its charge time is half an answer.
What you can check before buying
- Look for the port. USB-C on the toy is the best case for longevity. A magnetic puck means finding out whether the brand still sells a spare.
- Read owner feedback for the fade. Reviews written months after purchase are where a cell that no longer holds a charge shows up, and the pattern is unmistakable when it is there.
- Treat a very long advertised run time on a very powerful toy with suspicion. Energy has to come from somewhere, and a small cell cannot do both.
- Check whether the toy tells you anything. A charge indicator, even a crude one, is worth more in daily use than half an hour of extra run time, and plenty of toys give no indication at all until they stop.
- Store it around half charged. Not a purchase criterion, but the single habit that most extends the life of the cell, and therefore of the toy.
Questions people ask
- Can I leave it on the charger?
- A product with a proper charge controller stops when the cell is full, and most modern ones have one. Since you cannot see inside, the safer habit is to unplug it once charged, which costs you nothing.
- Why did my toy run for twenty minutes when the box said two hours?
- Almost always because the box figure is the lowest setting and you were using a high one, with the toy pressed against something, which adds load. An older cell makes the gap wider still.
- Can the battery be replaced?
- In nearly all cases, no. The cell is sealed in for waterproofing, and opening the shell ends the waterproofing even if the cell is reachable. A handful of larger mains or dock based products are exceptions.
- Does a toy use power when it is off?
- A little, in anything with a wireless connection or a wake sensor, since part of the circuit stays alive to listen. It is why an app connected toy left for a month is often flat when you pick it up, and why some have a travel lock that actually cuts the drain.