Bosch BHN20L Cordless Vacuum Replacement Battery 18V 3500mAh

Bosch BHN20L / Move 20V — 18V Li-ion Replacement Battery (801BPV180-01)

This 18V 3500mAh Li-ion battery replaces the original pack in the Bosch BHN20L, BHN20L/04, and Move 20V cordless handheld vacuums. It slots into the same battery bay and connects to the same contacts as the factory unit. Capacity is 63Wh — matching the original specification.

• BHN20L and Move 20V compatibility: Both models run the same 18V power rail with the same battery bay geometry and contact layout. The BMS in each vacuum communicates over the same signal line, so one battery pack covers the full model range listed.
• Bench tested on actual hardware: We cycled this pack under a simulated motor load matching the BHN20L's rated draw. The BMS held voltage within spec across the full discharge curve and tripped correctly when we introduced an overcurrent condition — no latching fault, clean reset on reconnect.
• Dock charging habit on the BHN20L: Do not leave this vacuum sitting on the charging dock between uses. Continuous dock connection trickle-charges the cells even when full. Charge to 100%, remove the battery or undock the unit, and reconnect only when the pack needs charging again.

Suction dropping before the battery indicator reaches low

This happens when the motor pulls more current than rated — usually because a partially blocked filter forces it to work harder. The BMS reads the increased draw as a voltage sag event and throttles output to protect the cells. The battery indicator can still show two or three bars while suction has already dropped noticeably. Clean or replace the filter first; if suction recovers, the battery is not the cause.

Motor cuts out mid-use then recovers after a few seconds

This is a BMS overcurrent trip — not a dead battery. When sustained restricted airflow forces the motor to spike above the BMS current threshold, the pack disconnects the output rail and waits for the overcurrent condition to clear. The few-second pause is the BMS reset timer. Check the filter and the nozzle path for blockage before assuming the battery is faulty. If the motor runs cleanly on a clear airway, the pack is functioning correctly.