Stanley FMC687L 18V Drill Battery 2000mAh Li-ion Replacement

Stanley FMC625D2 Series — 18V Li-ion Replacement Battery (FMC687L)

This is an 18V Li-ion replacement battery rated at 2000mAh (36Wh), built to the FMC687L specification. It fits the Stanley FMC625D2 compact drill/driver and a range of compatible 18V Stanley FatMax cordless tools including the FMC645D2, FMC675B, and FMC675B-XE. Check your model against the full fit list before ordering.

• FMC625D2 series compatibility: These models share a common 18V battery platform — same connector pinout, same BMS handshake protocol, and the same voltage rail that the tool's motor controller expects on startup. A mismatch in any of these stops the tool from accepting power.
• Bench tested on actual hardware: We ran this pack on the FMC625D2 drill under simulated fastening load. The BMS held stable across repeated trigger pulls, and cell voltage stayed within the tool's operating window throughout the test cycle. No false cutoffs were recorded.
• Motor inrush conditioning on first use: On first use, run the drill at half-load torque settings for two cycles before going to maximum torque. This gives the BMS time to profile the motor's inrush current draw and calibrate its overcurrent threshold before it encounters peak demand.

BMS cutoff on motor-start inrush surge in the FMC625D2

The FMC625D2's motor draws a spike of current in the first milliseconds of each trigger pull — this inrush current can be three to five times the steady running draw. On a new or storage-recovered pack, the BMS overcurrent threshold may not yet be calibrated to the motor's actual inrush profile. If the BMS reads that spike as a fault, it trips the protection circuit and cuts output before the motor reaches speed. Running two half-load cycles first lets the BMS log the inrush signature and set a threshold that accounts for it.

Charger blinking red on a new FMC687L pack after storage

Stanley 18V chargers have a minimum acceptance voltage — typically around 12–13V — below which the charger refuses to begin a charge cycle and signals a fault with a red blink pattern. Li-ion cells self-discharge during storage, and if the pack sat long enough, cell voltage can drop below that threshold. Place the battery on the charger and leave it for 15–20 minutes anyway; some Stanley chargers run a trickle wake-up cycle before switching to full charge. If the red blink persists past 20 minutes, check rail contact resistance — corroded terminals on either the battery or charger can read as an under-voltage condition even when cell voltage is sufficient.