CONTEC CMS5000 Replacement Battery 7.4V 4000mAh Li-Polymer AHB855183

CONTEC CMS5000 / CMS6000 Series — 7.4V Li-Polymer Replacement Battery (AHB855183)

This is a 7.4V 4000mAh (29.6Wh) Li-Polymer battery for the CONTEC CMS5000, CMS6000, CPM8000, and HMS6500 patient monitors. It replaces OEM part AHB855183 and restores portable operation for SpO2, heart rate, and blood pressure monitoring. Use it during patient transport or when mains power is unavailable.

• CMS5000, CMS6000, CPM8000, HMS6500 compatibility: These four monitors share the same 7.4V power rail, AHB855183 connector pinout, and BMS handshake protocol — one cell pack covers the full platform without modification.
• Bench tested on actual hardware: We cycled this cell on a CMS6000 unit and confirmed the BMS completed its charge verification handshake. The protection circuit tripped correctly at low-voltage cutoff and reset cleanly on reconnect.
• Post-swap startup protocol: After fitting this battery, allow the monitor to complete its full power-on self-test without interruption. The device runs a BMS verification sequence at boot — interrupting it triggers a false battery fault that persists until the next clean reboot.

Self-test failure on the CMS5000 after a battery swap

The CMS5000 runs a BMS learn cycle during its first few charge-discharge sequences on a new cell. Until that cycle completes, the monitor's charge IC applies a conservative current limit and may flag a battery warning even when the cell is healthy. This is not a fault with the replacement pack — it is the device calibrating to the new cell's internal resistance profile. Run one full charge-discharge cycle before using this battery in a clinical setting. The warning clears once the BMS registers a complete cycle.

Low battery alarm triggers immediately after a confirmed full charge

This happens when the BMS self-test threshold is tuned to the internal resistance signature of a conditioned OEM cell. A new Li-Polymer pack has higher impedance out of the box, so the monitor reads apparent voltage drop under load as a low-battery condition. The fix is straightforward — charge the battery fully, then discharge it under normal monitor use, and recharge again. After one complete cycle the impedance drops, the BMS reads it correctly, and the alarm does not return. Confirm full charge by checking the indicator reaches 7.4V at the battery terminals.