Robot vacuum won't charge? Diagnose it in 10 minutes
A robot that runs for ten minutes and dies — or never wakes up at all — almost always comes down to three suspects: the charging contacts, the dock and its power supply, or the battery itself. The trick is testing them in the right order so you don't buy a battery for a dock problem. Here's a step-by-step isolation you can run in about ten minutes with no tools.
Step 1: Clean the charging contacts (2 minutes)
The number-one cause of charging failure is the metal charging contacts on the robot's underside (and the matching pins on the dock) being coated in dust, pet hair film, or oxidation. A dirty contact can look fine but pass no current. Wipe the contacts on both the robot and the dock with a dry or barely-damp cloth, then a second pass with a dry one. A pencil eraser also works well for light oxidation on the metal pads. Don't use abrasive pads or liquids near the electronics — you only need the metal clean and shiny.
Also check that the spring-loaded pins on the dock actually spring. Press each one gently with a fingertip; it should depress and bounce back. A stuck pin means the robot never makes electrical contact no matter how clean the pads are, and cleaning or freeing the pin usually fixes it.
Step 2: Check the dock's power supply (2 minutes)
Unplug the dock's adapter, wait ten seconds, and plug it back in. Confirm the adapter is firmly seated in the wall outlet — wiggle it; wall outlets that barely grip are a common culprit. If the adapter has an indicator light, it should be on when plugged in. No light after reseating usually means a dead adapter or a broken cable where it enters the adapter body (the most common failure point).
Check the cable for damage along its length: kinks, chew marks, or crushed sections from furniture. The cable runs at low voltage, but a broken conductor inside the insulation will still kill charging. If you can swap in a matching adapter temporarily (same voltage and polarity — check the printed ratings on the adapter label), that settles it instantly: if the robot charges with the substitute adapter, replace the original.
Step 3: Fix dock placement and alignment (2 minutes)
The dock needs to sit on a flat, hard floor with clear space on both sides and in front, and its charging pins must line up with the robot's pads. Place the dock against a wall on level flooring — not on thick carpet, which lets it tilt back so the robot can't press firmly against the pins. Manually drive or place the robot onto the dock and watch it settle: it should dock firmly and the robot should indicate it's charging (a light, a sound, or a charging indicator on its display, depending on the model).
If the robot approaches the dock but never quite aligns, check for anything the infrared guidance might be bouncing off: mirrors, glass doors, or very reflective baseboards near the dock can confuse the homing signal. Moving the dock a meter or two to a plainer wall often solves mystery "won't dock" behavior.
Step 4: Rule out a software glitch (2 minutes)
If the hardware all looks fine, reset the robot. Most models have a hard reset — holding the power button down for ten or more seconds until it shuts off or chimes — plus a reset button or pinhole in the manual's troubleshooting section. Power the robot fully off, wait thirty seconds, and start it again on the dock. Charging logic is handled by firmware, and a hung charge controller is surprisingly common; a reset resolves it more often than people expect. Also check whether the companion app shows a specific charging error message, which can point straight at the failing component.
Step 5: Isolate the battery (2 minutes)
Here's the logic: if the contacts are clean, the pins spring, the adapter lights up, the robot docks and aligns, and a reset changed nothing — but the robot still shows no charge — the battery is the remaining suspect. Batteries degrade from heat, age, and full-discharge cycles, and a failing one may accept only a few minutes of charge or none at all. Symptoms that point at the battery rather than the dock: the robot charges for a very short time and reports full, runtime has been shrinking over weeks, or the unit gets unusually warm on the dock.
Before you buy a replacement, remove the battery (with the unit unplugged from the dock), check its connector for corrosion, and reseat it. A loose battery connector can mimic a dead battery exactly. If that doesn't help, replacement is the next step — see our battery replacement guide for the signs, safety precautions, and generic procedure.
When it's none of the above
If the robot charges on the dock but won't charge from a wall outlet directly (if your model allows that), the charging port on the robot may be damaged. If nothing on this list helps, note exactly which step failed — "pins spring, adapter lit, robot docks, no charge indicator" — because that sentence tells any repair shop (or support line) precisely where to look, saving you a round of questions.