About this replacement
Milwaukee 0401-1 / 0407-22 Series — 12V Ni-MH Replacement Battery (48-11-0140)
This is a 12V 3000mAh (36Wh) Ni-MH replacement battery for Milwaukee cordless drills and drivers in the 0401 and 0407 series. It fits over 28 models across those lines, including the 0401-1, 0401-4, 0407-22, and 0407-6. OEM part numbers covered include 48-11-0140, 48-11-0141, 48-11-0200, and 48-11-0251.
- 0401 and 0407 series compatibility: These models share a common 12V pack format, connector pinout, and BMS handshake protocol. The voltage rail and mechanical interface are identical across the platform, which is why one pack covers the full range without modification.
- Bench tested on actual hardware: We ran this pack through simulated motor-start inrush cycles on a 0401-series drill. The BMS held through repeated full-torque trigger pulls without tripping the overcurrent cutoff, and cell voltages balanced correctly across the string after each discharge.
- Break-in on first use: Run the drill at half load for two cycles before pushing maximum torque. This lets the BMS profile the motor's inrush current draw and set accurate overcurrent thresholds before hard use begins.
BMS cutoff on motor-start inrush in the 0401 and 0407 drills
When you pull the trigger on a cordless drill, the motor draws a spike of current well above its running load — this is inrush current. On Ni-MH packs, the BMS sets an overcurrent threshold based on early discharge profiles. If the pack goes into service without a break-in period, or after long storage, the threshold can sit too conservatively and trip the moment the motor spins up. The fix is two half-load cycles to allow the BMS to recalibrate. After that, full-torque use should proceed without nuisance cutoffs.
Tool bogs under load and feels underpowered mid-job
Voltage sag under load is the most common cause of a drill that starts fine but loses torque when it matters. On Ni-MH cells, internal resistance rises as the pack ages or if cells have been repeatedly shallow-cycled — meaning the battery never fully discharged before recharging. Check the pack rail contacts on the tool for corrosion or debris, since contact resistance compounds the sag. If contacts are clean, run the pack through two full discharge-recharge cycles; if voltage still drops below 10.8V under load, the cells need replacing.