Medfusion 4000 Pump 7.4V Replacement Battery 22-4050-51

Medfusion 4000 Syringe Pump — 7.4V Li-ion Replacement Battery (22-4050-51)

This 7.4V, 4600mAh Li-ion battery replaces part numbers 22-4050-51, 22-4050-51-C, and B11798 in the Medfusion 4000 and 4000 Syringe Pump. These are precision infusion pumps used to deliver IV medications and fluids at controlled rates in clinical and home care settings. Capacity matches the OEM spec at 34.04Wh.

• 4000 and 4000 Syringe Pump compatibility: Both models share the same 7.4V battery rail, connector pinout, and BMS handshake protocol. One cell fits both variants without modification.
• Bench tested on actual hardware: We ran this cell through the Medfusion 4000 boot sequence and charge cycle. The BMS accepted the cell, completed its verification pass, and the charge indicator advanced normally through all stages.
• Post-swap power-on sequence: After installing this battery, allow the pump to complete its full power-on self-test without interruption. The Medfusion 4000 runs BMS verification at startup — cutting power mid-sequence triggers a false battery fault flag that persists until the next full reboot.

Why the Medfusion 4000 flags a battery fault on a brand-new cell

The Medfusion 4000 BMS compares cell impedance and charge acceptance against stored OEM thresholds during its self-test. A new lithium cell has slightly elevated internal impedance before its first full charge-discharge cycle. This can push the reading outside the pump's acceptance window, triggering a battery fault alarm even when the cell is fully charged. Running one complete charge-discharge cycle on the pump normalises the cell's impedance profile and clears the condition.

Pump will not power on after battery sat unused in storage

Li-ion cells self-discharge at roughly 2–3% per month. A cell stored for six months or more can drop below the Medfusion 4000's BMS recovery threshold — typically around 2.5V per cell — causing the pump to refuse to boot. Connect the battery to the pump with the AC adapter attached and leave it for 15–30 minutes before attempting power-on. This allows the charge IC to trickle-charge the cell above the recovery floor. If the pump still does not boot, check that AC input is confirmed and the cell voltage at the connector reads above 5.0V before proceeding.