Black & Decker 83900-004 3.6V Ni-MH Replacement Battery

Black & Decker 11271 / S100 / S110 / S200 Series — 3.6V Ni-MH Replacement Battery (83900-004)

This is a 3.6V, 2100mAh Ni-MH battery pack for the Black & Decker 11271 and S-series cordless screwdrivers. It replaces OEM part numbers 83900-004, 151995-02, 383900-03, and VP110, among others. Fits the compact inline handle used across the 11271, S100, S110, and S200 models.

• S-series and 11271 pack compatibility: These models share the same 3.6V single-cell rail, connector footprint, and charge-termination behaviour. The pack slides into the same handle cavity across all listed variants, and the thermal cutoff trigger point matches the original cell specification.
• Bench tested on actual hardware: We cycled this pack through repeated load and charge sequences on a 11271-compatible test rig. The NTC thermistor line responded correctly to the charger's delta-V detection, and the pack reached full charge termination without false cutoffs.
• Ni-MH charge cycle tip for screwdrivers: Run two or three complete discharge-and-charge cycles before using the screwdriver at maximum torque settings — Ni-MH cells need conditioning cycles to reach rated capacity, and shallow partial charges on a new pack will depress usable voltage sooner than expected.

Why the S110 or 11271 loses drive torque mid-task even on a fresh charge

Ni-MH cells at 3.6V have a relatively flat discharge curve that drops off sharply at the tail end. When the cells age or are not fully conditioned, that cliff appears earlier in the cycle. The screwdriver's motor draws a brief inrush spike on each fastener engagement, and a weakened pack cannot sustain rail voltage through those pulses. The result is reduced clutch engagement or the tool feeling sluggish before the charge indicator suggests it should. Conditioning the new pack with two full discharge cycles before heavy use re-establishes the full usable voltage window.

Charger light stays solid red and never switches to green on the new pack

Black & Decker's delta-V chargers for this series reject packs that arrive below roughly 3.0V — a threshold the charger uses to screen out dead or shorted cells. A replacement pack that has sat in storage can drift below this acceptance voltage. Remove the pack from the charger, let it sit at room temperature for 20 minutes, then reinsert it. If the charger still rejects it, use a compatible trickle charger to bring the pack above 3.2V before returning it to the standard dock.