Panasonic 24V EY9116B Cordless Drill Replacement Battery 1500mAh

Panasonic EY6812NQKW Series — 24V Ni-MH Replacement Battery (EY9116B)

This is a 24V, 1500mAh Ni-MH replacement battery for the Panasonic EY6812NQKW cordless drill/driver and related models. It fits the EY6812NQRW, EY6812VQKW, and EY6813 series, sharing the same voltage rail, connector footprint, and BMS handshake as the original EY9116B pack. Capacity is 1500mAh (36Wh), matching the factory specification.

• EY6812 and EY6813 series compatibility: These drills share the same 24V slide-pack platform, connector pinout, and thermistor-based BMS communication. Any pack carrying the EY9116B, EY9117B, EY9210, EY9240, EY9242, or EY9244 part number slots into the same battery bay without modification.
• Bench tested on actual hardware: We cycled this pack on the EY6812 platform under repeated trigger-pull loads and monitored the BMS thermistor response. The overcurrent threshold held across cold-start and sustained torque cycles. Cell voltage stayed within the expected Ni-MH discharge curve throughout.
• First-use load conditioning on the EY6812: On first use, run the drill at half load — light fastening, no high-torque driving — for two full charge-discharge cycles. This lets the BMS sample actual motor inrush current before locking its overcurrent protection thresholds, reducing the chance of nuisance cutoffs during heavy driving later.

BMS overcurrent trip on motor-start inrush in the EY6812

When you pull the trigger on a Panasonic 24V drill, the motor draws a brief current spike — often two to three times the steady running load — before the bit begins to turn. On a new or freshly stored Ni-MH pack, the BMS may not yet have profiled that spike and can trip the overcurrent protection before the tool even spins up. The pack cuts out instantly, resets when you release the trigger, but trips again on the next pull. Running two conditioning cycles at reduced load gives the BMS enough data to set a realistic threshold for the EY6812 motor's actual inrush curve.

Charger not recognising the new pack after storage

Ni-MH packs that have sat in storage for several months can drop to a cell voltage the Panasonic charger reads as a fault, so the charge indicator blinks or the charger never starts. The charger's acceptance circuit looks for a minimum voltage before it opens the charge path — if the pack is below that floor, it stays locked out. Place the pack in the charger, leave it for 10–15 minutes, then remove and reinsert it; some Panasonic chargers will attempt a trickle pre-charge on the second insertion. If the charger still refuses the pack, confirm open-circuit voltage across the terminals is above 20V before trying again.