About this replacement
Metabo BS 12 SP — 12V Ni-MH Replacement Battery (6.25486)
This is a 12V 3000mAh Ni-MH replacement battery for the Metabo BS 12 SP compact drill-driver and related 12V models in the BSZ series. It slots into the same battery port and uses the same contact layout as the original Metabo 6.25486 pack. Capacity is rated at 36Wh.
- BS 12 SP, BSZ 12, BSZ 12 Impuls, BSZ 12 Premium compatibility: These models share the same 12V battery platform, connector footprint, and charge communication protocol. One battery fits all of them without adapter modification.
- Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on a BS 12 SP. The BMS responded correctly to motor-start inrush current without tripping overcurrent protection under normal trigger-pull conditions.
- Break-in for drill-driver use: On first use, run the drill at half load for two cycles before applying maximum torque. This lets the BMS log the motor's inrush current draw and set accurate overcurrent thresholds before you hit hard fasteners.
BMS overcurrent trip on motor-start inrush in the BS 12 SP
When you pull the trigger on a stalled or heavy load, the motor draws a current spike two to three times its running draw. On a freshly charged or recently stored Ni-MH pack, the BMS may not yet have a calibrated threshold for that spike. If the BMS reads the inrush as a fault, it cuts output instantly — the tool stops before it gets going. Running lighter cycles first gives the BMS the data it needs to distinguish a normal start spike from an actual short-circuit event.
Charger not recognising the pack after storage
Ni-MH packs left unused for several months can self-discharge below the voltage floor the charger looks for before starting a charge cycle. The charger sees the low voltage, treats the pack as defective, and refuses to begin. To recover the pack, use a charger with a conditioning or trickle mode to bring cell voltage up slowly to around 1.0V per cell. Once the pack reaches that threshold, the charger will accept it and complete a normal charge.