Safety first: Remove the battery pack before inspecting contacts. Do not short the terminals.

Step 1 – Clean contacts: Inspect the battery and vacuum contacts for oxidation or dirt. Clean gently with a dry cloth or a cotton swab with a small amount of isopropyl alcohol. Allow to dry fully.
Step 2 – Check for movement: Insert the battery and gently wiggle it. If the power cuts in and out or the LEDs flicker, the contact fit may be loose. Ensure the battery locks firmly into place.
Step 3 – Test with another battery (if available): If a second compatible Severin battery works normally, the original battery pack may have an internal BMS fault.
Step 4 – Avoid full depletion: Until repaired, avoid running the battery to automatic shutdown, as inaccurate sensing can over-discharge the cells.
Step 5 – Service if F3 persists: If F3 continues with clean contacts and a known-good battery, the main PCB voltage sensing circuit is likely defective and should be replaced by a technician.

Vacuum display shows F3; LED battery indicator behaves erratically (jumping from full to empty).

Possible Causes