DeWalt DE9057 7.2V Cordless Drill Replacement Battery 3000mAh

DeWalt DW920K / DW920K-2 Series — 7.2V Ni-MH Replacement Battery (DE9057)

This is a 7.2V, 3000mAh Ni-MH replacement battery for the DeWalt DW920K and DW920K-2 compact cordless screwdrivers. It replaces OEM part numbers including DE9057, DE9085, DW9057, and several others in the DE/DW90xx family. The battery slots directly into the pistol-grip housing and powers the motor through fastening and light drilling cycles.

• DW920 series compatibility: The DW920K, DW920K-2, DW925K, and related models share the same 7.2V battery rail, slide-pack connector, and BMS communication protocol — which is why a single cell pack covers the full range without modification.
• Bench tested on actual hardware: We ran this pack on a DW920K and cycled it through repeated trigger pulls under fastening load. The BMS held stable, the cell voltage recovered cleanly between pulls, and there were no overcurrent trips across the test cycle.
• Ni-MH break-in on the DW920 platform: On first use, run the screwdriver at half torque for two full discharge-charge cycles before hitting maximum clutch settings — this lets the BMS profile the motor's inrush current draw and set accurate overcurrent thresholds before heavy load work begins.

BMS overcurrent trip on trigger-pull inrush with the DW920K

When you pull the trigger on the DW920K, the motor draws a short inrush spike well above its steady-state current. On a new or storage-rested Ni-MH pack, the BMS may read that spike as an overcurrent event and cut the output before the motor reaches speed. This is more common when cell voltage is sitting below 6.8V at rest. Conditioning the pack with two light-load cycles before full-torque use gives the BMS real data to calibrate against, and the trip threshold stabilises.

Charger not recognising the pack after extended storage

DeWalt's 7.2V chargers check cell voltage before starting a charge cycle — if the pack has self-discharged below roughly 5V during storage, the charger sees it as a fault and refuses to initiate. With Ni-MH chemistry, this is a known behaviour, not a dead cell. A brief trickle-charge at 100–150mA for 10–15 minutes brings the pack voltage above the charger's acceptance threshold, after which the standard charge cycle starts normally. If the charger still blinks red after the trickle step, check rail contact resistance at the terminal — oxidised contacts can drop enough voltage to repeat the fault.