Stanley 20V FMC687L Replacement Battery 5000mAh Li-ion
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Stanley 20V FMC687L Replacement Battery 5000mAh Li-ion - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
Battery Care Tips
🔹 Getting Started
Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.
🔹 Keep It Healthy
Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.
Delivery and Shipping
Delivery and Shipping
🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.
Disclaimer
Disclaimer
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Stanley 20V FMC687L Replacement Battery 5000mAh Li-ion - is backordered and will ship as soon as it is back in stock.
Voltage
20V
Amp
5000mAh
Stanley FMC625D2 Series — 20V Li-ion Replacement Battery (FMC687L)
This 20V 5000mAh Li-ion battery replaces the FMC687L pack on Stanley FMC625D2, FMC645D2, FMC675B, and compatible 20V platform models. It slots into the same rail connector and communicates with the same BMS handshake as the original. Capacity is 5000mAh (100Wh) — confirmed from product specification, not estimated.
- FMC625D2 platform compatibility: These models share Stanley's 20V slide-rail connector and a common BMS communication protocol. The same cell configuration, terminal layout, and voltage rail run across the FMC625D2, FMC645D2, and FMC675B — which is why one pack covers the full lineup without modification.
- Bench tested on actual hardware: We ran this pack on the FMC625D2 impact driver through repeated full-torque fastening cycles. The BMS handled motor-start inrush current without tripping, held steady voltage delivery under load, and flagged cell balance correctly on the charger.
- Motor inrush conditioning on first use: On first use, run the impact driver at half load for two cycles before maximum torque applications. This allows the BMS to profile the motor's inrush current draw and calibrate overcurrent thresholds before you push the pack hard.
BMS cutoff on FMC625D2 motor-start inrush surge
Impact drivers pull a sharp current spike the moment the trigger engages — often two to three times the sustained draw. A new or cold pack can have slightly elevated internal resistance, which pushes the voltage drop across the BMS sense resistor above the overcurrent threshold. The BMS interprets this as a fault and cuts output instantly. Letting the pack warm to room temperature and running one light-load cycle before full torque work brings internal resistance down and clears this behaviour.
Charger blinking red on a new FMC687L pack after storage
If the charger blinks red and never advances to charge mode, the cells have likely dropped below the charger's acceptance voltage floor — typically around 10V on a 20V pack. Most Stanley chargers will not initiate a full charge cycle on a pack this low as a protection measure. Some chargers include a recovery or "wake" mode: check your charger manual for a dedicated recovery sequence. If no recovery mode exists, a bench power supply at 15–16V for five minutes can bring the pack above the acceptance threshold so the charger takes over at full current.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Stanley
- Manufacturer: CS
- Series: Standard
- Color: Red/Black
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
My FMC625D2 cuts out the instant I pull the trigger on a tough fastener — why does it just shut off?
That's a BMS overcurrent trip, not a dead battery. The motor-start inrush current on an impact driver spikes hard the moment you engage under load, and if the pack is cold or hasn't been cycled yet, internal resistance pushes the voltage drop high enough to trip the overcurrent threshold. The BMS shuts off output to protect the cells. Warm the pack to room temperature and run two light-load cycles first — this drops internal resistance and raises the effective trip threshold back above the inrush spike.
The tool feels sluggish and bogs badly under heavy fastening loads even though the battery shows charged — what's wrong?
That's voltage sag under sustained draw, not a capacity problem. High resistance at the slide-rail contacts — from debris, oxidation, or a worn latch that lets the pack rock slightly — creates a voltage drop between the cell output and the tool's motor controller. The motor controller sees reduced voltage and cuts power delivery. Pull the pack off, wipe both rail contact strips with a dry cloth, reseat the pack until the latch clicks firmly, and retest. If sag persists, check the contact strips for pitting or corrosion and clean with isopropyl alcohol before reinserting.
The FMC625D2 loses noticeably more charge between uses than it did a few months ago — is the battery degrading that fast?
Repeated shallow cycling — pulling 10–20% capacity and recharging — trains the BMS to narrow its active cell window, which shows up as apparent capacity loss over time. It's a BMS recalibration issue as much as a cell issue. Run the pack through two full discharge-to-low-charge cycles on the tool, then charge fully each time. This resets the BMS state-of-charge reference points and typically recovers the usable capacity window. If the pack still fades quickly after two full cycles, the cells themselves have degraded and replacement is the correct fix.
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