Panasonic EY9136B 15.6V Ni-MH Replacement Battery 2000mAh

Panasonic EY3530FQMKW Series — 15.6V Ni-MH Replacement Battery (EY9136B)

This is a 15.6V, 2000mAh Ni-MH battery pack for Panasonic cordless drill/drivers across the EY3530 and EY3531 series, plus compatible models sharing the EY9136B form factor. It replaces OEM part numbers EY9136B, EY9136, EY9137, EY9230, EY9230B, EY9219, EY9221, EY9223, and related variants. The connector, voltage rail, and cell layout match the original Panasonic pack specification.

• EY3530 and EY3531 platform fit: These drills share the same 15.6V battery slot, contact pin arrangement, and charge-communication protocol across both FQMKW and NQMKW variants — one battery services the full range without adapter plates or rewiring.
• Bench tested on actual hardware: We ran this pack on an EY3530 under repeated trigger pulls and verified the Ni-MH cell array holds the 15.6V rail through motor-start inrush without premature cutoff. Capacity measured at 2000mAh across full discharge cycles.
• Ni-MH conditioning on first use: Run the drill through two full discharge-and-charge cycles before heavy torque work — Ni-MH cells perform at rated capacity only after the electrodes have been fully cycled through their chemical range, not just rested at storage charge.

BMS cutoff on motor-start inrush during trigger pull

When you pull the trigger on an EY3530, the motor draws a spike of current well above its running load — this inrush lasts only milliseconds but it is the hardest event the battery pack faces. Ni-MH packs with aged or cold cells cannot sustain the voltage rail through that spike, and the overcurrent protection trips before the motor reaches speed. This is not a faulty battery — it is the protection circuit doing its job on a cell that cannot deliver the required instantaneous current. If this happens, warm the pack to room temperature and run two lighter cycles before returning to high-torque fastener driving.

Drill bogs and slows under sustained load mid-task

Voltage sag under sustained load — driving long screws or boring large-diameter holes — means the battery's internal resistance is climbing faster than the cells can recover between pulls. On a Ni-MH pack, this is often caused by repeated shallow cycling that never fully resets the cell chemistry. Check the contact rails on both the battery and the tool for oxidation or debris, as even 0.1Ω of added contact resistance collapses the rail voltage noticeably under load. If contacts are clean, run a full discharge to below 12V and a complete recharge cycle to reset the cell baseline.