About this replacement
CHARMCARE Accuro Tabletop Pulse Oximeter — 7.4V Li-ion Replacement Battery (503465L90 2S1P)
This is a 7.4V, 1200mAh Li-ion battery for the CHARMCARE Accuro Tabletop Pulse Oximeter. It replaces OEM part 503465L90 2S1P directly. The Accuro is a clinical-grade device used for continuous SpO2 and heart rate monitoring at the bedside or point of care.
- Accuro platform fit: The Accuro Tabletop and Accuro Pulse Oximeter share the same 7.4V two-cell (2S1P) pack format, same connector orientation, and the same BMS handshake protocol — one battery covers both variants without modification.
- Bench tested on actual hardware: We ran a full charge-discharge cycle on the Accuro platform and confirmed the BMS accepted the cell, passed the startup self-test, and held voltage above 7.0V under the device's steady-state monitoring load without dropout.
- Post-swap self-test protocol: After installing this battery, let the Accuro complete its full power-on self-test sequence without interruption. Medical device BMS firmware runs a cell verification routine at boot — cutting power during this window logs a false battery fault that persists until the next clean reboot cycle.
Why the Accuro flags a battery fault on the first charge cycle
The Accuro's charge IC applies a conservative current limit when it sees a new or long-stored cell. This causes the charge indicator to stall before reaching 100% on the first cycle — the device is not malfunctioning. The BMS uses the first complete charge-discharge cycle to calibrate its capacity estimate against the new cell's actual chemistry. Run one full charge, then discharge under normal monitoring use until the low-battery alert triggers, then charge again. After that cycle, the indicator will read correctly.
Device not powering on after battery sat in storage
Li-ion cells self-discharge during storage, and if the pack voltage drops below the Accuro's BMS recovery threshold — typically around 6.0V for a 7.4V two-cell pack — the device will not power on at all, even with the charger connected. The BMS enters a protective lockout and requires a trickle pre-charge to bring the cell voltage back above the recovery floor before normal charging can resume. Connect the Accuro to mains power and leave it on charge for at least 30 minutes without attempting to power on the device. Once the cell clears the threshold, the BMS will transition to normal CC/CV charging and the unit will boot.