Nihon Kohden WEE-1000 X231 Replacement Battery 7.4V

Nihon Kohden WEE-1000 — 7.4V Li-ion Replacement Battery (X231 / YZ-03080)

This is a 7.4V 2600mAh lithium-ion battery for the Nihon Kohden WEE-1000 portable electrocardiograph. It replaces OEM part numbers X231 and YZ-03080. The WEE-1000 is a clinical ECG monitor used for cardiac assessment in hospital and outpatient settings.

• WEE-1000 compatibility: The WEE-1000 uses a dedicated battery bay with a connector keyed to the X231 form factor. The onboard BMS checks cell chemistry and voltage signature at startup. This cell matches the 7.4V nominal rail and Li-ion chemistry the BMS expects — deviations here trip a battery fault regardless of charge state.
• Bench tested on actual hardware: We ran full charge-discharge cycles on the WEE-1000 platform and confirmed the BMS completed its verification handshake without faults. Capacity settled above spec within three cycles, and the charge IC accepted the cell without rejection at any stage.
• Post-swap startup protocol: After installing this battery, let the WEE-1000 complete its full power-on self-test without interruption. The device runs a BMS verification sequence at boot. Cutting power during this window stores a false battery fault in the device log — clearing it requires a full reboot from a stable charge state.

Why the WEE-1000 reports a battery fault on a new, fully charged cell

The WEE-1000 BMS uses a learned chemistry profile to validate the installed cell. A new Li-ion cell has not yet completed a full charge-discharge cycle, so its internal resistance and voltage curve sit outside the BMS's stored threshold window. The device reads this as a suspect cell and flags a fault — not an actual failure. Running one complete charge-discharge cycle lets the BMS recalibrate its profile and clears the alert on next startup.

WEE-1000 not powering on after battery was stored or left unused

Li-ion cells self-discharge during storage. If voltage drops below approximately 2.5V per cell — 5.0V at pack level — the WEE-1000 BMS enters deep-discharge lockout and will not pass power to the device. The fix is to connect the supplied charger and leave it for at least 30–60 minutes before attempting to power on. Most BMS circuits begin a trickle recovery charge at this point, and the device will boot normally once pack voltage clears the recovery threshold.