Fischer FSS18V 400 BL Compatible Battery 18V 3000mAh Li-ion

Fischer FSS18V 400 BL Series — 18V Li-ion Replacement Battery

This is an 18V 3000mAh (54Wh) Li-ion replacement battery for the Fischer FSS18V 400 BL cordless drill/driver sets. It fits the FSS18V 400 BL Set 1 through Set 4 and additional variants in the same series. All share the same 18V platform, connector format, and BMS communication protocol.

• FSS18V 400 BL platform compatibility: Every FSS18V 400 BL set variant runs the same 18V rail and uses the same battery slot and contact arrangement. The BMS handshake across these sets is identical, so one battery pack covers the full range without modification.
• Bench tested on actual hardware: We ran this pack through repeated trigger-pull cycles on an 18V drill platform and monitored the BMS response to motor-start inrush current. The overcurrent threshold held correctly across all test pulls, and cell balancing stayed within spec after full charge-discharge cycles.
• Motor load conditioning on first use: On first use, run the drill at half load — driving short screws into soft timber — for two full cycles before applying maximum torque. This lets the BMS log the motor's inrush current signature and set its overcurrent protection thresholds accurately before you push the tool hard.

BMS cutoff on FSS18V 400 BL motor-start inrush surge

The FSS18V 400 BL brushless motor draws a sharp inrush current spike the moment you pull the trigger — this can be three to five times the steady-state running current. If the BMS has not yet profiled the motor's signature, it may interpret that spike as a fault and cut power immediately. A new or storage-rested pack is most vulnerable to this because the BMS protection thresholds reset to conservative defaults. Running two light-load conditioning cycles re-calibrates those thresholds to the actual motor profile before full-load use.

Charger not recognising the pack after storage

Li-ion cells that have sat unused for several months can drop below 2.5V per cell — the minimum voltage most chargers will accept before initiating a charge cycle. When this happens, the charger sees the pack as a fault condition and either blinks red or does nothing. Place the battery in a warm environment (18–25°C) for 30 minutes, then re-seat it firmly in the charger. If the charger still rejects it, check that the rail contacts on the battery and charger port are clean and making full contact — corroded contacts reduce the voltage signal the charger reads at the terminals.