Seca 645 Digital Scale Replacement Battery 7.2V 2000mAh

Seca 645 / 665 / 682 / 757 Series — 7.2V Ni-MH Replacement Battery (68 22 12 721 009)

This is a 7.2V, 2000mAh Ni-MH replacement battery for Seca medical scales. It fits the 645, 665, 682, and 757 models, along with 17 additional Seca scale variants. The OEM part number is 68 22 12 721 009, also cross-referencing EE050388, PA-A1994-12317, and BA-A921-CA.

• Multi-model fit across the Seca scale range: These models share the same 7.2V Ni-MH battery architecture, connector type, and BMS handshake protocol. A single cell specification covers the full group without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Seca scale unit. The BMS completed its verification handshake cleanly, and the charge IC accepted the cell without flagging a chemistry mismatch.
• Post-installation self-test protocol: After fitting this battery, allow the scale to complete its full power-on self-test without interruption. Seca scales run a BMS verification sequence at startup — cutting power during this step triggers a false battery fault that persists until the next clean reboot.

Why a Seca scale won't complete its boot sequence on a new battery

Seca medical scales run a BMS learn cycle during the first few charge-discharge passes. A freshly installed Ni-MH cell carries a resting voltage that the charge IC treats with conservative thresholds until it has one full cycle of data. If the scale stalls mid-boot or loops back to the startup screen, the cell voltage is likely sitting just under the BMS acceptance threshold. Charge the unit fully, let it discharge through normal use once, then recharge — the BMS updates its acceptance window after that first complete cycle.

Scale alarming low battery immediately after a confirmed full charge

This happens when the BMS reads cell voltage against thresholds calibrated for a worn OEM cell chemistry profile. A new Ni-MH cell at full charge can show a voltage curve the BMS briefly interprets as anomalous. The alarm clears after one complete charge-discharge cycle, which gives the BMS enough data to recalibrate its low-voltage trigger. Do not use the scale clinically until that first full cycle is complete — run the cycle on the bench and confirm the alarm does not reappear before returning the unit to patient use.