Bistos BT-740 Pulse Oximeter Compatible Battery 11.1V 6700mAh

Bistos BT-740 / BT-770 Pulse Oximeter — 11.1V Li-ion Replacement Battery (022-000021-00)

This is an 11.1V 6700mAh Li-ion replacement battery for the Bistos BT-740 and BT-770 pulse oximeters. It fits both the BT-740 and BT-770 platforms and replaces OEM part number 022-000021-00. Capacity figure is taken directly from product data at 74.37Wh.

• BT-740 and BT-770 platform fit: Both models run the same 11.1V three-cell architecture with an identical connector and BMS handshake protocol. A single battery revision covers both units because Bistos kept the power rail and cell communication bus consistent across the BT-700 series refresh.
• Bench tested on actual hardware: We cycled this battery through the BT-740 charge circuit and confirmed the BMS negotiation completed cleanly. Cell balancing engaged on the first charge, and the protection board held within the device's accepted voltage window throughout discharge.
• Post-swap startup protocol: After installing this battery, let the device complete its full power-on self-test without interrupting it. The BT-740 runs a BMS verification sequence at boot — cutting power mid-cycle logs a battery fault that persists until the next uninterrupted reboot.

Device not completing boot sequence on new battery

The BT-740's firmware checks the battery's state-of-charge report during the boot sequence. A new cell that has partially self-discharged in storage can report a voltage the device reads as a fault — typically below 10.5V on an 11.1V pack. The device stalls at the initialisation screen or loops back to the startup logo. Charge the battery fully before the first boot, then let the self-test run to completion without touching the power button.

Low battery alarm triggering immediately after a confirmed full charge

This happens because the device's BMS threshold was calibrated against a conditioned OEM cell with an established charge history. A new replacement cell has not completed a learn cycle, so the protection board's state-of-charge estimate is conservative and reads low even at full voltage. Run one complete charge-to-discharge cycle on the device before clinical use. After that first cycle the BMS recalibrates its threshold and the false alarm stops.