Stanley FMC687L 18V Replacement Battery 5000mAh Li-ion

Stanley FMC688L Series — 18V Li-ion Replacement Battery (FMC687L)

This is an 18V Li-ion replacement battery carrying 5000mAh (90Wh) of capacity. It fits the Stanley FMC688L cordless drill/driver and a range of compatible 18V Stanley tools including the PCC680L, PCC685L, and PCCK602L2. Slot it into any FMC687L-compatible port and the BMS handshakes with the charger automatically.

• FMC688L platform fit: The FMC688L, PCC680L, PCC685L, and PCCK602L2 all share the same 18V rail, connector footprint, and BMS communication protocol. One battery pack covers the full lineup without adapter modifications.
• Bench tested on actual hardware: We ran this pack on the FMC688L through repeated trigger pulls under load. The BMS held the voltage rail steady during motor-start inrush and recovered without tripping overcurrent protection across all test cycles.
• Break-in on first use: Run the drill at half load — light fastening, no high-torque driving — for the first two charge cycles. This lets the BMS sample the motor's inrush current draw and set its overcurrent thresholds accurately before you push maximum torque applications.

BMS cutoff on motor-start inrush with the FMC688L

When you pull the trigger hard from a dead stop, the motor draws a short, sharp current spike before it reaches running speed. On a new or cold pack, the BMS may read that spike as an overcurrent event and cut the output rail. This is a protection response, not a fault. Release the trigger, wait three seconds, and restart at a slower squeeze. After two or three cycles, the BMS calibrates to the motor's inrush profile and the cutoffs stop.

Charger blinking red on a new 18V pack after storage

Li-ion cells self-discharge during warehouse storage. If cell voltage drops below roughly 2.5V per cell, most Stanley 18V chargers refuse to begin a normal charge cycle and signal the fault with a red blink pattern. Place the pack on the charger and leave it for 20–30 minutes without interrupting — most Stanley chargers run a slow recovery trickle at around 100mA before stepping up to full charge. If the red blink persists past 30 minutes, check that the terminal contacts are clean and seated fully, then retry. The pack should reach the green charge indicator once cells climb above the acceptance threshold.