Criticare Systems 602-11 Replacement Battery 12V 2300mAh

Criticare Systems 602-11 / Scholar II / VSM 5070P — 12V Sealed Lead Acid Replacement Battery

This is a 12V 2300mAh (27.6Wh) sealed lead acid battery for the Criticare Systems vital signs monitor range. It fits the 602-11, 602-13, Scholar II, VSM 5070P, and eight additional models in the same platform family. These monitors run on portable battery power during patient transport, ward rounds, and any period without AC access.

• 602-11 / Scholar II / VSM 5070P platform compatibility: These models share the same 12V SLA battery bay, connector pinout, and BMS handshake protocol. A replacement at matching voltage and capacity slots into the same charge circuit without modification.
• Bench tested on actual hardware: We ran this cell through the monitor's internal charge cycle and confirmed the BMS accepted the cell, completed charge termination correctly, and logged no fault codes during the self-test sequence.
• Post-installation self-test protocol: After fitting this battery, allow the monitor to complete its full power-on self-test without interruption. Cutting power mid-sequence causes a false battery fault flag that persists until the next clean reboot — not a cell defect.

Why the 602-11 alarms low battery immediately after a confirmed full charge

The monitor's BMS stores a learned capacity baseline from the previous cell. A new SLA cell arrives with a surface charge, not a true full charge, and its internal resistance profile doesn't yet match the stored baseline. The BMS reads this mismatch as a degraded or low cell and trips the alarm even though the cell itself is fine. One complete charge-discharge cycle resets the learned baseline and clears the alarm. After that first cycle, the battery indicator should track normally.

Monitor will not power on after the replacement cell sat in storage

Sealed lead acid cells self-discharge at roughly 3–5% per month. A cell stored for several months can drop below the BMS recovery threshold — typically around 10.5V for a 12V SLA — at which point the monitor's protection circuit blocks startup entirely to prevent deep-discharge damage. Connect the monitor to AC power for a minimum of 12 hours before attempting a battery-powered boot. If the cell has dropped below 10V, the charge IC may need a slow trickle phase before the BMS re-enables normal charge current.