Bayco XPR-9850 Replacement Battery 3.6V 7000mAh

Bayco XPR-9850 / XPR-9860 — 3.6V Ni-MH Replacement Battery (XPR-9850BATT)

This is a 3.6V, 7000mAh Ni-MH replacement battery for the Bayco XPR-9850 and XPR-9860 rechargeable flashlights. It slots in as a direct cell replacement when the original pack loses capacity or stops holding charge. Capacity is 25.2Wh — matched to the original specification.

• XPR-9850 and XPR-9860 compatibility: Both models use the same OEM part number (XPR-9850BATT) and share an identical cell format, voltage rail, and connector. One replacement covers either light without modification.
• Bench tested on actual hardware: We cycled this cell through the XPR-9850 driver at full output and stepped down through standard mode. The Ni-MH chemistry held voltage above the driver's brownout threshold through the full discharge curve before the light stepped down.
• Single-cell replacement note: The XPR-9850 runs on one large-format Ni-MH cell rather than a multi-cell pack. When replacing, make sure the contact springs are clean and unobstructed — corrosion on the spring contacts is the most common cause of intermittent connection after a new cell is installed.

Flashlight driver stepping down output before the battery reads low

The XPR-9850 driver monitors cell voltage continuously and steps output down before the battery indicator triggers. Ni-MH cells have a flatter discharge curve than Li-ion, so the driver hits its brownout threshold while the cell still has usable charge remaining. This is intentional — the driver protects the cell from over-discharge, which permanently reduces Ni-MH capacity. If the light dims unexpectedly, switch to a lower output mode to keep the cell above the 1.0V cutoff and extract the remaining charge.

Significantly shorter output in turbo mode compared to standard mode

Turbo mode on the XPR-9850 draws current at a rate far higher than standard or low mode — often five to ten times greater. A 7000mAh Ni-MH cell delivers its rated capacity at moderate draw rates; at turbo-level current, internal resistance causes the cell voltage to sag faster and the driver cuts output sooner. This is a chemistry constraint, not a fault with the replacement cell. To get the most out of a full charge, use turbo in short bursts and drop to standard mode for sustained illumination.