QCore Sapphire Multi-Therapy 7.4V 1800mAh Replacement Battery

QCore Sapphire Multi-Therapy — 7.4V Li-ion Replacement Battery (LIN337-001)

This 7.4V, 1800mAh lithium-ion battery replaces the original power cell in the QCore Sapphire Multi-Therapy and SapphirePlus portable therapeutic units. It fits OEM part numbers LIN337-001 and 05020-160-0001-BAT. The cell dimensions are 55.96 x 34.12 x 21.40mm, matching the original bay exactly.

• Sapphire and SapphirePlus platform compatibility: Both the Sapphire Multi-Therapy (15031-000-0001) and SapphirePlus (15038-043-0001) share the same voltage rail, connector pinout, and BMS handshake protocol — one cell covers both platforms without modification.
• Bench tested on actual hardware: We cycled this cell through charge, load, and self-test sequences. The BMS accepted the cell on first contact, passed the protection circuit checks, and held voltage within the device's operating window under therapeutic load conditions.
• Post-swap self-test protocol: After installing this cell, allow the Sapphire to complete its full power-on self-test without interruption. The device runs a BMS verification routine at startup — cutting power during this sequence logs a false battery fault that persists until the next clean reboot.

QCore Sapphire alarming low battery immediately after a confirmed full charge

The Sapphire's charge IC applies a conservative acceptance threshold calibrated to the OEM cell's existing charge history. A new cell with no cycle history may not satisfy that threshold on the first charge, triggering a low-battery alarm even when the cell is at or near full capacity. The BMS needs one complete charge-discharge cycle to map the new cell's actual capacity curve. Run the device through one full clinical-load discharge down to device cutoff, then recharge fully — the alarm clears once the BMS has a baseline to work from.

Device will not power on after the replacement cell sat unused in storage

Lithium-ion cells self-discharge during storage. If this cell has been sitting for several months, its resting voltage may have dropped below the Sapphire's BMS recovery threshold — typically around 6.0V for a 7.4V nominal pack — and the device will refuse to boot. Connect the charger and leave the cell on charge for a minimum of 30 minutes before attempting to power on. If the charge indicator does not respond within that window, the cell voltage is likely below the charger's own recovery floor; try a different compatible charger capable of trickle recovery before drawing any other conclusion.