Rockwell RW9351.1 18V Replacement Battery 4000mAh Li-ion

Rockwell RD2865 Series — 18V Li-ion Replacement Battery (RW9351.1)

This is an 18V 4000mAh Li-ion battery built to fit the Rockwell RD2865, RD2871, RD2872, RD2873, and over 30 additional compatible models. It replaces OEM part RW9351.1. The 72Wh rating supports full tool operation across drills, impact drivers, and other compact cordless tools in the RD28 range.

• RD28 series platform fit: These models share a common 18V rail, connector footprint, and BMS handshake protocol. One battery services the full range without adapter workarounds or firmware mismatches.
• Bench tested on actual hardware: We ran this pack through repeated motor-start inrush cycles on an RD2865 drill. The BMS tracked overcurrent events without nuisance tripping and held voltage within spec under sustained load.
• Break-in on first use: Run the tool at half load for two cycles before full-torque applications. This lets the BMS profile the motor's inrush current draw and calibrate its overcurrent thresholds before you push maximum demand.

BMS cutoff on motor-start inrush surge in RD28 drills

When you pull the trigger on a stalled or heavily loaded drill, the motor draws a short, sharp current spike — sometimes three to five times the running current. If the BMS has not yet profiled the motor's inrush signature, it can interpret that spike as a fault and cut output. This is more common with new packs straight from storage. Running two break-in cycles at reduced load gives the BMS enough data to set realistic overcurrent thresholds before full-torque work begins.

Charger not recognising the pack after storage

Li-ion cells self-discharge during storage. If the pack drops below approximately 2.5V per cell, most chargers will refuse to initiate a charge cycle — the voltage is too low for the charger's acceptance threshold. Some chargers show a blinking red light; others show nothing at all. If this happens, check whether your charger has a recovery or "wake" mode — hold it in that mode for five minutes, then attempt a normal charge cycle. If the cell voltage has not dropped below the hard cutoff, the pack will recover.