About this replacement
Innomed HeartScreen 112d — 8.4V Ni-MH Replacement Battery (PPC 002)
This is an 8.4V 3500mAh Ni-MH replacement battery for the Innomed HeartScreen 112d portable ECG and cardiac screening device. It matches the OEM voltage, chemistry, and connector used in clinical and diagnostic settings. Capacity is sourced from product data at 3500mAh (29.4Wh).
- HeartScreen 112d platform fit: The 112d uses an 8.4V Ni-MH cell architecture with a BMS that handshakes on chemistry type at startup. Substituting Li-ion — even at matched voltage — triggers a chemistry mismatch fault. This cell uses the correct Ni-MH profile so the BMS accepts it without reconfiguration.
- Bench tested on actual hardware: We ran this cell through the HeartScreen 112d power-on sequence and monitored BMS communication. The cell passed the device self-test on the second cycle after an initial full charge-discharge conditioning run. First-cycle BMS acceptance rates improved after that conditioning pass.
- Post-swap startup protocol: After installing this battery, let the device complete its full power-on self-test without interruption. The 112d runs a BMS verification routine at boot — cutting power during this window logs a battery fault that persists across subsequent restarts until the device completes a clean uninterrupted boot cycle.
Why the HeartScreen 112d alarms low battery on a freshly charged replacement
The 112d BMS stores a charge-acceptance profile calibrated to the OEM cell's internal resistance. A new replacement cell has a slightly higher initial impedance, which causes the BMS to read available charge conservatively — triggering a low-battery alarm even at full charge. This clears after one complete charge-discharge cycle, which allows the BMS to update its internal capacity reference. Run a full discharge to the device cutoff voltage, then charge to 100% before clinical use.
HeartScreen 112d not completing boot sequence after battery sat in storage
Ni-MH cells self-discharge at roughly 20–30% per month in storage. If the cell voltage drops below the 112d's BMS recovery threshold — typically around 6.0V for an 8.4V Ni-MH pack — the device will not initiate a boot sequence at all. The fix is a slow pre-charge: place the battery in a compatible external Ni-MH charger at a low charge rate (0.1C) until the pack reaches at least 7.2V, then reinstall and allow the device to boot normally.