National EY9210 24V Cordless Drill Replacement Battery 1500mAh

National EY6812NQKW Series — 24V Ni-MH Replacement Battery (EY9210B)

This is a 24V, 1500mAh Ni-MH replacement battery for the National EY6812NQKW and related cordless drill and driver models. It replaces OEM part numbers EY9116B, EY9117B, EY9210, EY9210B, EY9240, EY9242, EY9244, and EY9116. Fit models include the EY6812NQKW, EY6812NQRW, EY6812VQKW, and EY6813 series.

• EY6812 and EY6813 platform compatibility: These models share the same 24V battery rail, connector pinout, and BMS handshake protocol — which is why a single pack covers the full range. Swapping between variants in this group does not require any charger or tool-side adjustment.
• Bench tested on actual hardware: We cycled this pack through repeated drill and driving loads, monitoring BMS response during motor-start inrush spikes. The overcurrent threshold held without nuisance tripping across all tested trigger-pull events, and cell temperature stayed within normal operating range under sustained torque loads.
• Motor inrush break-in on first use: Run the drill at half load — light driving tasks, not max-torque fastening — for the first two cycles. This lets the BMS profile inrush current from the actual motor before setting its overcurrent protection thresholds. Skipping this step on a cold pack can cause premature cutoff on the first hard application.

BMS cutoff on EY6812 motor-start inrush surge

When you pull the trigger on a stalled or heavily loaded drill, the motor draws a current spike that can be three to five times the running load. On a new or recently stored Ni-MH pack, the BMS has not yet mapped the motor's inrush profile and may interpret this spike as a fault. The protection circuit opens, the tool cuts out, and the pack appears dead even though the cells are fully charged. Allowing two light-load warm-up cycles resolves this — the BMS logs the inrush pattern and raises the trip threshold accordingly.

Tool bogs under load and recovers when trigger is released

This symptom points to voltage sag — the pack's terminal voltage drops under sustained draw, the tool loses torque, and voltage rebounds the moment current demand drops. On Ni-MH cells, sag worsens as internal resistance rises with age or from repeated shallow cycling. Check the battery contact rails on both the tool and the pack for oxidation or debris, as added contact resistance amplifies sag. If contacts are clean and the symptom persists, measure resting voltage after a full charge — a healthy 24V Ni-MH pack should read at least 25.2V at rest.