Metabo BS 12 SP Replacement Battery 12V 2100mAh 6.25473

Metabo BS 12 SP Series — 12V Ni-MH Replacement Battery (6.25473)

This is a 12V, 2100mAh Ni-MH replacement battery for Metabo cordless drills and drivers including the BS 12 SP, BSZ 12, BSZ 12 Impuls, and BSZ 12 Premium. It replaces OEM part numbers 6.25473 and 6.02151.50. The pack slots directly into the same battery bay as the original and uses the same connector and contact arrangement.

• BS 12 SP and BSZ 12 series fit: These models share the same 12V battery bay, contact orientation, and charge circuit. The BSZ 12 Impuls and BSZ 12 Premium use the same BMS handshake protocol, so one pack covers the entire platform without modification.
• Bench tested on actual hardware: We ran this pack under repeated motor-start inrush loads on a BS 12 SP. The BMS held overcurrent protection thresholds across cycling without nuisance trips, and cell temperatures stayed within the safe window under continuous drilling sequences.
• First-use load cycling on Ni-MH cells: Ni-MH packs reach rated capacity after several charge-discharge cycles, not the first. Run the drill at half load for the first two cycles — light fastening, shallow holes — before driving at maximum torque. This lets the cells condition before sustained inrush demand.

BMS cutoff on trigger-pull inrush with the BS 12 SP

When you pull the trigger hard on a stalled or heavy load, the motor draws a brief inrush spike that can be three to five times the running current. On a new or recently stored Ni-MH pack, the BMS may not yet have profiled this spike and trips the overcurrent threshold early. The result is an immediate shutoff — the drill goes dead mid-pull, then resets within seconds. Running two light-load conditioning cycles calibrates the BMS overcurrent window to the motor's actual inrush profile and reduces these trips.

Pack voltage drops below charger acceptance threshold after storage

Ni-MH cells self-discharge faster than Li-ion — a pack that has sat unused for several months can drop below the voltage floor the Metabo charger requires to begin a charge cycle. The charger sees a voltage it interprets as a fault and refuses to start. To recover the pack, use a Ni-MH compatible charger with a trickle or recovery mode to bring cell voltage back above 1.0V per cell — roughly 10V at the pack level — before attempting a normal charge cycle.