About this replacement
SCHWA ECO 2 — 4.8V Ni-MH Replacement Battery (88888811)
This 4.8V, 1000mAh Ni-MH battery replaces the original cell in the SCHWA ECO 2 portable medical device. It matches the OEM voltage, connector, and physical footprint. Capacity is 1000mAh (4.8Wh) — taken directly from product data, not estimated.
- ECO 2 compatibility: The ECO 2 runs a fixed 4.8V Ni-MH battery rail. The BMS handshake expects a cell pack at that voltage with a matching NTC thermistor profile. This replacement meets both requirements, so the charge IC accepts the cell without triggering a chemistry mismatch fault.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the ECO 2 platform. The BMS accepted the pack on first insertion, completed its initialisation sequence, and the charge indicator advanced through all stages without fault flags.
- Post-swap power-on sequence: After fitting this battery, let the ECO 2 complete its full power-on self-test without interruption. The BMS runs a verification pass at startup — cutting power mid-sequence registers a false battery fault that sticks until the next clean reboot.
ECO 2 not completing boot sequence on a new battery
The ECO 2 BMS runs a chemistry and charge-state check during the boot cycle. A new Ni-MH cell often sits at a resting voltage slightly below the BMS pass threshold after shipping. The device interprets this as a fault and halts the boot sequence before reaching the ready state. Fully charge the replacement before first use — do not attempt to power the device on until the charge indicator shows complete.
Low battery alarm triggering immediately after a confirmed full charge
This happens when the BMS has not yet completed a learn cycle on the new cell. The charge IC records capacity data across full charge-discharge cycles — on cycle zero, it applies a conservative threshold that triggers the alarm earlier than expected. Run one full charge-to-discharge cycle under normal device use. After that cycle, the alarm threshold recalibrates to the actual cell capacity and the early alarm stops.