SunTech CT40 Monitor Compatible Battery 7.4V 10200mAh

SunTech CT40 Monitor — 7.4V Li-ion Replacement Battery (9005BAT)

This 7.4V, 10200mAh Li-ion battery replaces the original pack in the SunTech CT40 portable vital signs monitor. The CT40 is used in clinical and ambulatory settings for continuous blood pressure, pulse, and vital parameter monitoring. Voltage and capacity match OEM spec — part numbers 9005BAT, 120044-O, ND2057HD34, and SUN17-0022-00 all cross to this cell.

• CT40 platform fit: The CT40 uses a fixed 7.4V two-cell Li-ion configuration with a BMS that validates cell chemistry at startup. The connector, cell count, and communication protocol must match OEM spec — this pack is built to those parameters so the monitor's battery handshake completes without a fault flag.
• Bench tested on actual hardware: We ran this pack through the CT40's power-on self-test sequence and charge cycle. The BMS accepted the cell without triggering a battery fault, charge IC reached full capacity without throttling, and the self-test completed cleanly on the second full cycle.
• Post-swap startup protocol: After fitting this battery, allow the CT40 to complete its full power-on self-test without interruption. The BMS runs a verification routine at boot — cutting power mid-sequence locks in a false battery fault that persists until the next clean reboot from full charge.

Why the CT40 flags a battery error after a confirmed full charge

The CT40's charge IC applies a conservative acceptance threshold on first contact with a new cell. If the cell voltage sits slightly outside the BMS's learned range — common in fresh stock that hasn't been cycled — the monitor logs a battery fault even after a full charge. This isn't a defective pack. The BMS needs one complete charge-discharge cycle to calibrate its state-of-charge model against the new cell. After that cycle, the fault clears and the monitor reads capacity correctly.

CT40 won't power on after the battery sat in storage

Li-ion cells self-discharge during storage at roughly 1–2% per month. If the pack voltage drops below approximately 6.0V — the CT40's BMS deep-discharge recovery threshold — the monitor won't boot and shows no response on the power button. Connect the monitor to mains power and leave it charging without attempting to power on for at least 60 minutes. The charge IC will trickle-charge the cell back above the BMS recovery threshold, after which a normal boot sequence will initiate.