Ridgid AC840084 18V Replacement Battery 4000mAh Li-ion

Ridgid 130383001 Series — 18V Li-ion Replacement Battery (AC840084)

This 18V, 4000mAh Li-ion battery replaces the Ridgid AC840084 pack across the 130383001, 130383025, 130383028, and R840084 tool platforms. It fits cordless drill drivers and impact drivers in the Ridgid 18V lineup. Capacity is rated at 4000mAh (72Wh) — drawn from the product spec, not extrapolated.

• 18V platform fit — 130383001, 130383025, 130383028, R840084: These models share the same 18V rail, battery connector geometry, and BMS handshake protocol. The AC840084 OEM part number covers all four, so one pack services the entire group without adapter or modification.
• Bench tested on actual hardware: We ran this pack through repeated motor-start inrush cycles on a drill driver and an impact driver. The BMS held the overcurrent threshold correctly on each trigger pull and recovered to full rail voltage between cycles without tripping into protection mode.
• Break-in load cycling: On first use, run the tool at half load for two cycles before applying maximum torque. This lets the BMS profile the motor's inrush current draw and calibrate its overcurrent protection thresholds before you hit it with full-load applications.

BMS cutoff on motor-start inrush surge in 18V Ridgid tools

When you pull the trigger on a drill driver or impact driver, the motor draws a short current spike — often two to three times the steady-state load — before it reaches running speed. If the BMS registers that spike above its overcurrent threshold, it shuts down the pack immediately. A worn or corroded terminal contact raises resistance on the rail and amplifies the apparent spike the BMS sees. Clean the battery contacts with isopropyl alcohol and reseat the pack firmly before assuming the battery is faulty.

Charger shows blinking red on a new AC840084 pack after storage

Li-ion packs sitting unused in a warehouse or on a shelf will self-discharge over time. If the cell voltage drops below roughly 2.5V per cell, most Ridgid chargers will not enter normal charge mode and instead signal a fault with a blinking red LED. Some chargers include a recovery or conditioning mode — check your charger's indicator sequence for a slow blink versus a fast blink, as the pattern distinguishes a low-voltage recovery state from a genuine fault. Leave the pack on the charger in recovery mode for at least 30 minutes; if the LED does not transition to solid red or green charging, check that the charger output terminals are clean and making firm contact with the pack.