About this replacement
Panasonic EY6107 Series — 12V Ni-MH 3300mAh Replacement Battery (EY9200)
This is a 12V Ni-MH 3300mAh replacement battery pack for the Panasonic EY6107 cordless drill/driver and compatible models including the EY6470NQ, EY6903NQ, and EY6506NQ. It replaces OEM part numbers EY9200, EY9200B, EY9106B, PA-1204N, and several others in the same 12V platform. Voltage and pack dimensions match the original housing to ensure proper contact alignment in the tool's battery bay.
- EY6107 platform compatibility: These drill models share the same 12V battery bay geometry, terminal layout, and charge handshake circuit. One pack fits across the range because Panasonic held that connector and voltage rail consistent across the EY6xxx series generation.
- Bench tested on actual hardware: We cycled this pack on the EY6107 platform through repeated trigger-pull sequences and monitored the BMS response to motor-start inrush current. The pack held voltage within spec across the test cycles without tripping overcurrent cutoff under normal load conditions.
- Ni-MH break-in on first use: Run the drill at moderate load for two full discharge-charge cycles before applying maximum torque. Ni-MH cells benefit from this conditioning step — capacity stabilises faster and the pack reaches rated 3300mAh delivery sooner than if pushed hard from the first charge.
BMS cutoff on EY6107 motor-start inrush surge
Cordless drills pull a short, sharp current spike the moment you pull the trigger — this inrush can be three to five times the steady running draw. On a fresh or cold pack, the BMS protection circuit can read that spike as an overcurrent event and cut the output immediately. Ni-MH packs are more tolerant of inrush than Li-ion, but a pack that sat discharged in storage for months will have elevated internal resistance, making the voltage dip at trigger-pull sharper and more likely to trip the BMS. Two conditioning cycles at half load will lower internal resistance and reduce the risk of nuisance cutoff on hard starts.
Charger not recognising a new pack after storage
Ni-MH packs self-discharge during storage, and if a pack sits long enough, cell voltage can drop below the threshold the charger uses to confirm a valid battery is connected. The charger sees a voltage reading outside its acceptance window and either blinks an error or does nothing. To recover the pack, check the terminal voltage with a multimeter — if individual cells read below 1.0V, the charger may not engage. Some Panasonic chargers for this platform include a refresh or recovery mode; activating that mode applies a low-rate trickle charge to bring cells back above the acceptance threshold before switching to normal charge current.