About this replacement
Nihon Kohden CardioAir ECG-2010 — 3.7V Li-ion Replacement Battery (SB-202D)
This is a 3.7V 2900mAh Li-ion replacement for the Nihon Kohden SB-202D battery pack. It fits the CardioAir ECG-2010 portable electrocardiograph. Capacity matches the original specification at 10.73Wh.
- CardioAir ECG-2010 platform fit: The ECG-2010 uses a single-cell Li-ion pack at 3.7V nominal with a connector and BMS handshake matched to the SB-202D form factor. This cell meets that voltage rail and physical envelope — 64.40 × 44.70 × 13.00mm — so the pack seats and communicates correctly with the device charge controller.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the ECG-2010 and monitored BMS communication at each stage. The charge IC accepted the cell without fault codes, and the BMS passed state-of-charge reporting through to the device display as expected.
- Post-swap startup on medical hardware: After inserting this battery, allow the ECG-2010 to complete its full power-on self-test without interruption. The device runs BMS verification at boot. Cutting power during that sequence causes a false battery fault flag that persists until the next full reboot cycle.
Why the ECG-2010 shows a low battery alarm immediately after a confirmed full charge
The ECG-2010's charge management IC calibrates state-of-charge against cell chemistry data stored from the previous pack. A new cell arrives with an uncalibrated BMS profile, so the device reads capacity conservatively and triggers the low battery threshold even at full charge. This clears after one complete charge-discharge cycle, which lets the BMS rewrite its capacity baseline. Run the device through a full clinical session to discharge below 20%, then charge back to 100% before clinical deployment.
ECG-2010 will not power on after the replacement battery sat in storage
Li-ion cells self-discharge during storage. If this cell dropped below the ECG-2010's BMS recovery threshold — typically around 2.5V for a 3.7V nominal cell — the device will not power on even when connected to the charger. The BMS applies a trickle pre-charge at low current to recover the cell before switching to standard CC/CV charging. Leave the device on charge for a minimum of 30 minutes before attempting to power on, allowing the pre-charge stage to bring the cell above 3.0V.