Microsoft Xbox One X Wireless Controller B100 Replacement Battery 2.4V 2500mAh Ni-MH

Microsoft Xbox One Wireless Controller — 2.4V Ni-MH Replacement Battery (B100)

This is a 2.4V, 2500mAh Ni-MH rechargeable battery pack built to the B100 specification. It fits the Xbox One X, Xbox One S, and Xbox One Elite wireless controllers. Install it when the original cell no longer holds a charge or the controller shuts down mid-session.

• Xbox One X, One S, and Elite controller fit: All three controllers share the same battery bay geometry, B100 connector pitch, and 2.4V supply rail. The charge circuit expects a Ni-MH cell at this voltage — swapping the pack does not require any firmware or pairing reset.
• Bench tested on actual hardware: We ran this pack in an Xbox One S controller and monitored charge acceptance from the dock. The BMS accepted a full charge cycle without throttling and the fuel gauge updated correctly across the session.
• First-cycle calibration for the Xbox One fuel gauge: After installing, run one complete wireless play session to automatic controller cutoff before recharging. The Xbox fuel gauge IC sets its empty reference point against the first full discharge — skipping this step leaves the gauge reading high and cutting out unexpectedly.

Why the Xbox One controller drops wireless connection before the battery indicator hits empty

The Xbox One wireless radio and rumble motors pull current simultaneously during heavy gameplay. On a degraded or uncalibrated Ni-MH cell, this combined load drags cell voltage below the controller's radio threshold before the fuel gauge reaches one bar. The controller reads the voltage drop as a signal loss event, not a low-battery event, so the indicator shows partial charge at the moment of disconnect. Running the calibration cycle described above lets the controller distinguish a real voltage sag from a low-capacity condition.

Fuel gauge jumping between charge levels after fitting a new pack

The Xbox One fuel gauge IC builds its discharge curve from historical cycle data stored against the old cell. A new cell with a different internal resistance produces a different voltage-versus-capacity curve, so the gauge misreads remaining charge until it relearns. This shows up as the indicator jumping from three bars to one bar without warning. Complete three to five full discharge-and-recharge cycles and the gauge IC recalibrates to the new cell's curve.