Silvercrest Cordless Window Vacuum Compatible Battery 3.7V 3400mAh

Silvercrest SFR 3.7 D3 / HG004476 — 3.7V Li-ion Replacement Battery

This 3.7V 3400mAh (12.58Wh) Li-ion cell replaces the original battery in the Silvercrest Cordless Window Vacuum Cleaner, covering models HG004476 and SFR 3.7 D3. The window vac draws water and suds from glass surfaces using a squeegee head and internal reservoir — no cord, no streak marks. When the original cell loses capacity, suction weakens before the indicator even reaches low.

• HG004476 and SFR 3.7 D3 compatibility: Both models run the same 3.7V single-cell architecture with an identical BMS handshake and connector footprint. The cell dimensions — 66.32 × 20.20 × 18.40mm — match the original cavity precisely, so no modifications are needed during swap.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the SFR 3.7 D3 platform. The BMS accepted the replacement without error flags, and the motor drew cleanly within rated current throughout each cycle.
• Dock charging discipline for this device: The Silvercrest window vac has no active charge termination beyond the BMS. Leaving it on the charging cradle after a full charge trickle-damages the cell over weeks. Charge to full, remove from the dock, and reconnect only when the battery is depleted.

Suction dropping before the battery indicator reaches low

The SFR 3.7 D3 motor voltage sags under load before the cell voltage drops far enough to trigger the low-battery LED. A partially blocked filter or full reservoir forces the motor to draw more current than rated, accelerating that sag. The result is noticeably weaker suction while the indicator still shows charge remaining. Clear the filter and empty the reservoir first — if suction then recovers, the cell is likely fine. If sag persists on a clean filter, the cell has lost capacity and resting voltage will measure below 3.5V.

Motor cuts out mid-clean then restarts after a few seconds

This is a BMS overcurrent trip, not a motor fault. When airflow is restricted — blocked filter, overfull reservoir, or pressed too hard against the glass — current draw spikes and the BMS cuts the circuit to protect the cell. The brief pause lets the BMS reset, then power returns. Fix the restriction first: clear the filter and check the reservoir. If cut-outs continue on a clean, empty device, charge the battery fully and confirm resting voltage holds above 3.6V before ruling the cell out.