Welch-Allyn VS100 Replacement Battery 10.8V 3350mAh

Welch-Allyn VS100 Vital Signs Monitor — 10.8V Li-ion Replacement Battery (34004)

This 10.8V, 3350mAh Li-ion battery replaces the original Welch-Allyn 34004 and 30018-EX cells in the VS100 vital signs monitor. The VS100 is a portable clinical device used at bedside and in assessment rooms to measure blood pressure, SpO2, heart rate, and temperature. Install this battery when the original no longer holds charge or triggers persistent low-battery alerts during patient assessments.

• VS100 and VS100 Spot Vision Screener compatibility: Both devices share the same 10.8V battery bay, connector pinout, and BMS handshake protocol. One cell covers both units without modification.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the VS100 platform. The BMS accepted the new cell, completed its initialisation sequence, and reported accurate state-of-charge without fault codes.
• Post-swap power-on sequence: After installing this battery, let the VS100 complete its full power-on self-test without interruption. The device runs BMS verification at startup — cutting power during this sequence can generate a false battery fault that persists until the next clean reboot.

VS100 low-battery alarm triggering immediately after a confirmed full charge

The VS100's charge IC applies a conservative charge ceiling to new cells on the first cycle. This means the battery may report 90–95% state-of-charge rather than 100%, and the device's alarm threshold can read that as a low-battery condition. The BMS needs one complete charge-to-discharge cycle to calibrate its capacity estimate against the new cell's actual chemistry. Run one full cycle before placing the monitor in clinical rotation — the alarm clears once the BMS has a confirmed baseline.

VS100 not completing boot sequence after battery replacement

A new cell that has self-discharged during storage can sit below the VS100's BMS recovery threshold — typically around 9V per cell group for 10.8V Li-ion packs. Below this voltage, the BMS locks out discharge to prevent cell damage, and the monitor stalls partway through its boot sequence or fails to power on at all. Connect the device to its AC adapter before pressing power — this allows the charger to pre-condition the cell above the recovery threshold first. Once the charge indicator moves and voltage climbs past 10V, the device will boot and complete its self-test normally.