robot says 'charging error, please check charging contacts' and won't charge on the dock.

Diagnosis

This error occurs when the Roborock Q7 Max cannot establish a stable electrical handshake with the charging dock. While the robot may physically be sitting on the dock, the voltage transfer is being interrupted by a layer of non-conductive debris. This is typically caused by a buildup of "electro-oxidation"—a thin, invisible layer of carbon or oxidation that forms on the nickel-plated contacts—combined with fine household dust and pet hair that creates a physical barrier. In some cases, the issue is caused by the robot not being perfectly aligned with the dock. If the robot is skewed by even 5mm, the spring-loaded pins on the dock may not fully compress against the robot's contact plates, triggering the "charging error" voice prompt. You can confirm the root cause by inspecting the contacts under a bright light; if you see a dull, greyish film or a dark ring around the edges of the metal plates, the connection is compromised.

How to Fix It

Follow these steps precisely to restore the electrical connection:

1. Power down the system by unplugging the charging dock from the wall outlet to prevent any short-circuiting during the cleaning process.
2. Turn the Roborock Q7 Max upside down and locate the two silver rectangular charging plates on the underside of the chassis.
3. Using a clean, dry microfiber cloth dipped in 70% isopropyl alcohol, scrub the plates firmly. If you see black residue or "burnt" spots, use a standard pencil eraser to vigorously rub the metal until it appears bright and shiny.
4. Move to the charging dock. Locate the two spring-loaded pins on the charging ramp. Use a cotton swab dipped in isopropyl alcohol to clean the tips of these pins. Gently press the pins down with your finger to ensure they spring back up smoothly and are not stuck in a recessed position.
5. Clean the floor area directly in front of the dock. Ensure there are no loose rugs or debris that could cause the robot to enter the dock at a slight angle.
6. Plug the dock back in and manually place the robot onto the charging pins. Listen for the confirmation chime and check the LED ring to ensure it transitions from a flashing state to a steady charging indicator.

If That Didn't Work

• Check for Dock Displacement: Ensure the dock is flush against a flat wall. If the dock is leaning forward or backward by even a few degrees, the Q7 Max will fail to seat properly on the contacts. Use a spirit level to ensure the dock is perfectly vertical.
• Inspect for Pin Deformation: Look closely at the dock's charging pins. If one pin is pushed further in than the other, it may have lost its spring tension. You can sometimes gently pull the pin out with tweezers to reset the spring, but if the internal spring is snapped, the dock assembly must be replaced.
• Test the Power Brick: Check the power cable for any kinks or frays, especially near the dock connection. If the power adapter is failing to provide a consistent 24V output, the robot will detect a voltage drop and trigger the "charging error" even if the contacts are clean.
• Hard Reset the Logic Board: Press and hold the Power and Home buttons simultaneously for 10 seconds to force a reboot of the onboard controller. This clears any temporary software glitches that might be misreporting the charging status.

Heads Up

• Avoid using abrasive scouring pads or steel wool on the contacts, as this will strip the nickel plating and lead to rapid corrosion.
• Perform a "contact polish" every 30 days as part of your routine maintenance to prevent the buildup of oxidation.
• Ensure the dock is placed on a hard surface; placing it on a thick carpet can cause the dock to tilt, leading to intermittent charging failures.
• Keep the area 0.5 meters in front of and 0.5 meters on either side of the dock clear of obstacles to ensure the robot aligns itself perfectly every time.