Cordless vacuum shows E9; LED battery indicator behaves erratically (jumps from full to empty, shuts off unexpectedly).

Safety first: Power OFF the vacuum and remove the battery before cleaning contacts.

• Clean and reseat battery: Wipe the battery and vacuum contacts with a dry cloth. Reinsert the battery firmly until it locks.
• Perform a full discharge/charge cycle: Use the vacuum continuously on normal mode until it stops by itself. Then charge it fully without interruption (at least 3–4 hours). This can recalibrate the fuel gauge.
• Observe runtime: After calibration, time how long the vacuum runs on a full charge. If runtime is significantly below the specification, the battery cells may be worn.
• Avoid partial top‑ups only: Frequent very short charges can confuse the gauge. Occasionally perform full cycles to maintain calibration.
• Replace if needed: If E9 persists and runtime is poor, replace the battery pack. If runtime is normal but the indicator is still erratic, the main PCB may require service.