Black & Decker FS360 Replacement Battery 3.6V 2000mAh

Black & Decker FS360 / FS360 Type 1 3.6V Ni-MH Replacement Battery (90500500)

This is a 3.6V, 2000mAh Ni-MH replacement battery for the Black & Decker FS360 and FS360 Type 1 cordless screwdriver. It replaces OEM part number 90500500. Voltage and capacity match the original pack spec exactly.

• FS360 and FS360 Type 1 fitment: Both variants run the same 3.6V single-rail architecture with the same physical connector block and cell cavity dimensions. The BMS handshake threshold is identical across both Type designations, so one pack covers both without modification.
• Bench tested on actual hardware: We cycled this pack through the FS360 charger and monitored cell voltage at the terminals during charge acceptance and cutoff. The BMS terminated charge cleanly at full capacity with no false cutoff or trickle-lock on the first cycle.
• Ni-MH memory cycle reset on the FS360: Unlike Li-ion packs, Ni-MH cells in the FS360 benefit from a full discharge-then-recharge cycle if the tool has been sitting unused for more than three months. Run the tool until torque noticeably drops, then charge fully before returning to normal use.

Why the FS360 cuts out instantly on trigger pull after a long storage period

Ni-MH cells that have self-discharged below approximately 0.9V per cell will cause the BMS to trip on the inrush current spike the moment the motor tries to start. The pack reads as present on the charger but the voltage rail collapses the instant load is applied. This is not a faulty battery it is a protection response to undervoltage cells. Charge the pack for a full uninterrupted cycle before the first trigger pull to bring all cells above the BMS acceptance threshold.

FS360 charger light stays solid red and never switches to green

A solid red light that never advances to green usually means the charger is detecting a cell voltage too low for normal charge acceptance common after extended storage. The FS360 OEM charger requires each cell to sit above roughly 1.0V before it will begin the main charge cycle. Remove the pack, let it rest at room temperature for 15 minutes, then reseat it firmly in the charger. If the light shifts to green within a few minutes, the cells have recovered enough voltage for the charger to accept the pack.