Cordless vacuum shows E14 and the LED battery indicator behaves erratically (jumping from full to empty).

Safety: Remove the battery from the vacuum.

• Clean and reseat: Clean the contacts and firmly reseat the battery several times to ensure good electrical connection.
• Fully charge and discharge: Perform a full charge, then run the vacuum continuously on low until it stops. Recharge fully again. This can recalibrate some fuel gauge systems.
• Compare with another battery: If a second battery shows normal behavior, the original pack's gauge circuit is faulty.
• Do not open the pack: Replace the battery pack rather than attempting internal repair.