About this replacement
Hitachi CK 12D / CL 10D Series — 9.6V Ni-MH 3000mAh Replacement Battery (EB 920HS)
This is a 9.6V, 3000mAh Ni-MH replacement battery for Hitachi cordless drills and drivers including the CK 12D, CK 12DY, CL 10D, and D 10D. It replaces a wide range of Hitachi OEM packs including EB 920HS, EB 920RS, EB 926H, EB 930H, EB 930R, and related part numbers. The cells match the original voltage rail so the tool's torque control and trigger response behave exactly as the factory pack did.
- CK 12D and CL 10D platform fit: These models share the same 9.6V slide-type pack connector, battery housing latch, and terminal orientation. No adapter is needed — the pack seats and locks the same way as the original Hitachi cell assembly.
- Bench tested on actual hardware: We ran this pack through repeated trigger-pull cycles on a CK 12D, monitoring cell voltage and BMS response. The pack recovered cleanly from inrush spikes at motor start and held voltage within the expected range across sustained driving loads.
- Ni-MH conditioning on first use: Run the drill at half load — light screwdriving, not max-torque fastening — for the first two charge-discharge cycles. Ni-MH cells build consistent capacity when the initial cycles avoid peak current draw, which sets the baseline for the tool's clutch feel at higher torque settings later.
Inrush current trip on the CK 12D at trigger pull
When a Ni-MH pack sits discharged for weeks, the cells can drop below the level where the tool's internal protection circuit accepts a full motor-start surge. The moment you pull the trigger, the BMS sees an inrush spike — often 3–5× the running current draw — and cuts power to protect the cells. This is not a faulty battery. Charge the pack fully before the first use and allow the charger to complete its cycle without interruption. A pack reading above 10.2V off the charger will handle motor-start inrush without tripping on the CK 12D.
Drill bogs and slows under sustained load mid-task
Voltage sag happens when cell impedance rises — either from age on the original pack or from a new pack that hasn't been conditioned. On the CK 12D, this shows up as the drill losing torque progressively through a long boring or driving run rather than cutting out suddenly. Check the terminal contacts on the battery housing: oxidised or dirty slide contacts add resistance and worsen sag significantly. Clean the terminals with a dry cloth and recheck; if the pack still reads below 8.8V under load, the cells need a full conditioning cycle before heavy use.