Kärcher VCN 3 25.2V Replacement Battery 3000mAh 8.759-985.0

KARCHER VCN 3 / VCN 4 Series — 25.2V Li-ion Replacement Battery (8.759-985.0)

This is a 25.2V 3000mAh (75.6Wh) lithium-ion battery pack for the KARCHER VCN 3 and VCN 4 cordless handheld vacuum cleaners. It fits the OEM slot directly and uses the original part number 8.759-985.0. Capacity figures are taken from the product specification — not estimated.

• VCN 3 and VCN 4 compatibility: Both models run the same 25.2V motor rail and use the identical battery housing and BMS handshake protocol. A single pack covers all four listed variants — VCN 3, VCN 3 Cordless Vacuum Cleaner, VCN 4, and VCN 4 Cordless Vacuum Cleaner.
• Bench tested on actual hardware: We cycled this pack through repeated motor-start loads simulating blockage conditions. The BMS held the overcurrent threshold correctly and did not trip on normal suction draws. Cell balance across the pack stayed within spec after ten full discharge cycles.
• Dock charging on the VCN 3 and VCN 4: Do not leave this vacuum on the charging dock continuously. These models trickle-charge when docked and full, which accelerates capacity fade in Li-ion cells. Charge to full, then remove from the dock.

Suction dropping before the battery indicator reaches low

The VCN 3 and VCN 4 motors pull significantly more current when airflow is restricted — a partially blocked filter can push draw well above the rated figure. The BMS reads this as a high-load event and steps down the voltage rail to protect the cells, which the user feels as suction loss. The battery indicator measures state of charge, not current draw, so it can still show two bars while the motor is already running in a throttled state. Clean the filter first — if suction recovers immediately, the battery was not the issue.

Motor cuts out mid-use and then restarts after a few seconds

This is a BMS overcurrent trip, not a depleted cell. It happens when sustained restricted suction forces the motor to draw above the pack's continuous current limit — the BMS cuts output, the motor stops, the BMS resets, and the motor restarts. The cycle repeats until the restriction is cleared. Check the filter and the intake path for blockage before assuming the battery is faulty. If the motor runs cleanly after clearing the blockage, the pack is operating as expected.