Festool BPS12C 12V Ni-MH Replacement Battery 2100mAh

Festool C12 Series — 12V Ni-MH 2100mAh Replacement Battery (BPS12C)

This is a 12V Ni-MH replacement battery rated at 2100mAh (25.2Wh) for the Festool C12 cordless tool platform. It fits the C12, C12LI, and associated model numbers including 564247 and 497019. The battery slots into the same bay as the original BPS12C, BPS12, and BPS12S packs.

• C12 platform compatibility: The C12 and C12LI share the same 12V battery bay, connector pinout, and BMS communication protocol. Both models draw from the same voltage rail, so one replacement pack covers the full C12 compact drill and driver line without adapter changes.
• Bench tested on actual hardware: We cycled this pack through the C12 drill under simulated load conditions. The BMS handled motor-start inrush without tripping, cell balance held across repeated charge and discharge cycles, and terminal voltage stayed within the expected window under sustained drive applications.
• Ni-MH warm-up behaviour on the C12: For the first two charge cycles, run the drill at moderate load before full torque applications. Ni-MH cells deliver lower current at low temperatures and need a few cycles to reach stable internal resistance — pushing maximum torque too early can cause premature voltage sag during high-load fastening.

BMS cutoff on C12 motor-start inrush surge

The C12's compact motor pulls a sharp current spike the moment the trigger engages — significantly higher than the steady running current. On a pack that has been sitting unused, the BMS may read this spike as an overcurrent event and cut output before the motor reaches speed. This is most likely on a cold or freshly charged pack where the cells haven't settled to working temperature. Running one light-load cycle first lets the BMS log the motor's inrush profile and set its threshold above the spike rather than below it.

C12 drill bogs under load but battery shows charged

If the drill slows noticeably under torque even though the pack reads as charged, the cause is usually voltage sag — the terminal voltage drops under draw faster than the charge indicator can reflect. On Ni-MH cells, this worsens if the pack has been repeatedly topped up from partial discharge, which compresses the usable capacity window over time. Check the battery terminal contacts on both the pack and the tool for corrosion or debris causing added resistance. Clean the contacts and run the pack through two full discharge-to-charge cycles to restore a stable capacity baseline.