Hilti TCD12 12V Ni-MH Compatible Battery 3300mAh

HILTI TCD12 / SID121 / SF121 Series — 12V Ni-MH Replacement Battery (00315082)

This is a 12V, 3300mAh Ni-MH battery pack for the HILTI TCD12, SID121, SF121, and SF121-A cordless tools. It replaces OEM part numbers 00315082, 00340470, SB12, SBP12, SFB125, SFB120, and SFL12. The pack slots directly into the tool's battery bay and communicates with the onboard electronics the same way the original does.

• TCD12, SID121, SF121, and SF121-A platform: These four models share the same 12V rail, battery bay geometry, and contact layout. One pack fits all of them without adapters or firmware changes.
• Bench tested on actual hardware: We cycled this pack through repeated motor-start events on the TCD12 and SF121. The BMS held stable through trigger-pull inrush spikes and did not drop the load unexpectedly during continuous fastening runs.
• Ni-MH break-in on drill platforms: On first use, run the tool at half load for two full discharge-charge cycles before applying maximum torque. This lets the cell group equalise charge distribution before the BMS sets its overcurrent baseline against the motor's inrush profile.

BMS overcurrent trip on motor-start inrush in the SF121 and TCD12

At trigger pull, a 12V drill motor draws a brief inrush current that can be three to five times its running current. A new or cold Ni-MH pack has slightly elevated internal resistance, which raises the instantaneous voltage drop across the BMS sensing circuit. If that drop crosses the protection threshold, the BMS interprets it as a fault and cuts the output. Running two break-in cycles at partial load trains the BMS to the actual inrush signature of this specific motor, reducing nuisance trips on full-torque applications.

Charger shows no activity or blinks fault after the pack has been in storage

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A pack stored for several months can drop below 9V total, which falls outside the acceptance window of some HILTI chargers. The charger then refuses to begin a standard charge cycle and either blinks an error or shows nothing. To recover the pack, most HILTI chargers have a recovery or conditioning mode — consult the charger's indicator sequence. If recovery mode is unavailable, a trickle charge at 100–200mA to bring each cell above 1.0V per cell (12V total across the pack) is enough to re-enter the charger's normal acceptance range.