About this replacement
Metabo BSZ 18 Series — 18V Ni-MH Replacement Battery (6.25484)
This 18V Ni-MH battery replaces part number 6.25484 and fits the Metabo BSZ 18, BSZ 18 Impuls, BSZ 18 Impuls Li, and BSZ 18 Impuls Li Power cordless drill/driver range. Capacity is 3300mAh (59.4Wh). It restores full voltage and torque delivery to worn or failed packs.
- BSZ 18 series compatibility: All models in this range share the same 18V battery rail, connector pinout, and BMS handshake protocol. One pack covers the full lineup without adapter modifications.
- Bench tested on actual hardware: We cycled this pack through repeated motor-start inrush loads on BSZ 18 hardware. The BMS handled the trigger-pull current spike without tripping overcurrent protection under normal drill and drive conditions.
- Break-in procedure for BSZ 18 clutch cycles: On first use, run the tool at half-torque clutch settings for two full charge cycles before pushing maximum torque applications. This lets the BMS profile the motor's inrush draw and set accurate overcurrent thresholds before heavy fastening work.
BMS cutoff on BSZ 18 motor-start inrush surge
When you pull the trigger on a Ni-MH pack that has been sitting discharged, the initial motor-start inrush current can spike two to three times the steady running current. A cold or storage-depleted pack has elevated internal resistance, which compounds the voltage sag at that spike. If the BMS reads the rail voltage dropping below its cutoff threshold during that surge, it trips the overcurrent protection and the tool stops instantly. Charge the pack to full before first use after any storage period, and avoid trigger-jabbing at full speed into high-resistance materials until the pack has completed one full break-in cycle.
Charger not recognising the pack after storage
Ni-MH cells self-discharge during storage, and if the pack voltage drops below roughly 10V on an 18V pack, most Metabo chargers will not enter normal charge mode — the indicator will blink or show a fault. The charger's acceptance circuit expects a minimum cell voltage before it begins the charge sequence. To recover the pack, some chargers include a recovery or conditioning mode; check your charger model for that function. If no recovery mode exists, a brief trickle charge at 0.1C from an external source can bring the pack above the 10V acceptance threshold so the standard charger will then engage normally.