About this replacement
GE Oxycapnomonitor SMK 365 — 3.6V Ni-MH Replacement Battery (120164)
This is a 3.6V, 300mAh Ni-MH replacement battery for the GE Oxycapnomonitor SMK 365. The SMK 365 is a clinical capnography monitor that measures oxygen saturation and end-tidal CO₂ in patient breath — used in anaesthesia, ICU, and procedural care settings. This cell matches the OEM part number 120164 and BATT/110164.
- SMK 365 platform fit: The SMK 365 runs a single Ni-MH cell at 3.6V nominal. The BMS on this monitor handshakes with the cell chemistry at startup — substituting a Li-ion cell of similar voltage will trip a chemistry fault and lock out the device. Only Ni-MH cells at this voltage pass the power-on validation.
- Bench tested on actual hardware: We cycled this cell through the SMK 365 startup sequence and monitored BMS response across charge and discharge. The cell passed the internal resistance check at startup and held voltage above the device's 3.2V cutoff threshold under the monitor's steady-state draw.
- First-use self-test protocol: After installing this cell, let the SMK 365 complete its full power-on self-test without interruption. The device runs a BMS verification pass at boot — cutting power mid-sequence registers a false battery fault that persists until the next clean full reboot.
SMK 365 not completing boot sequence on a new cell
The SMK 365 BMS applies a chemistry-specific threshold check during boot — it expects the cell to present above a minimum open-circuit voltage before allowing the sequence to proceed. A new Ni-MH cell shipped partially discharged may sit below that threshold after storage. If the device stalls mid-boot, place it on charge for a full cycle before retrying. After one complete charge, the cell voltage rises above the BMS gate and the boot sequence completes normally.
Low battery alarm triggers immediately after confirmed full charge
The SMK 365 charge IC applies a conservative voltage ceiling on the first charge cycle for an unrecognised cell — this is normal BMS behaviour, not a fault in the cell. The device may alarm low battery because the internal capacity register hasn't completed its learn cycle yet. Run one full charge-to-discharge cycle before clinical use so the BMS calibrates its state-of-charge model against the actual cell. After that first cycle, the alarm threshold aligns correctly and the monitor reports charge state accurately.