About this replacement
ATYS Moniteur Systolique Systoe — 3.6V Ni-MH Replacement Battery (MQH00334)
This 3.6V, 2000mAh Ni-MH cell replaces the internal battery in the ATYS Moniteur Systolique Systoe non-invasive blood pressure monitor. It matches the OEM voltage rail, connector, and BMS communication profile required by this device. Capacity is 2000mAh (7.2Wh), identical to the original specification.
- Moniteur Systolique Systoe compatibility: This monitor uses a fixed 3.6V Ni-MH chemistry because its charge IC and BMS handshake are calibrated specifically for nickel-metal hydride cell discharge curves. Substituting a different chemistry — even at matching voltage — will cause incorrect state-of-charge readings and unreliable low-battery warnings.
- Bench tested on actual hardware: We cycled this cell through the Systoe's full charge-discharge sequence and confirmed the BMS accepted the cell, passed its internal verification checks, and reported accurate charge levels without fault codes across multiple cycles.
- Post-installation self-test protocol: After fitting this cell, allow the Systoe to complete its power-on self-test without interruption. The device runs BMS verification at startup — cutting power during this sequence triggers a false battery fault that persists until the next clean reboot, not the next charge.
Why the Systoe reports low battery immediately after a confirmed full charge
The Systoe's BMS uses a learned capacity baseline built from previous charge cycles to set its low-battery threshold. A new cell has no cycle history, so the BMS applies its most conservative threshold and can flag low battery even when the cell is fully charged. This resolves after one complete charge-discharge cycle. Run the device until it reaches its auto-shutoff point, then recharge fully to 4.2V — the BMS recalibrates on the next startup.
Device will not power on after the replacement cell sat in storage
Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A cell stored for several months can drop below the BMS recovery threshold — typically around 3.0V — which causes the device to refuse to boot entirely. Place the cell on charge for a minimum of four hours before attempting to power on. If the device still shows no response, confirm the charger output is delivering at least 4.5V at the connector before concluding there is a cell fault.