Nightstick XPR-5522GMX Replacement Battery 3.7V 3400mAh

Nightstick XPR-5522GMX — 3.7V Li-ion Replacement Battery (5522-BATT)

This is a 3.7V 3400mAh Li-ion battery built to fit the Nightstick XPR-5522GMX dual-light rechargeable flashlight. It replaces OEM part number 5522-BATT directly. When the original cell degrades, this swap restores full output across both the main and secondary light heads.

• XPR-5522GMX compatibility: The 5522-BATT cell is specific to this dual-head form factor. The physical dimensions — 80.20 × 38.30 × 25.50mm — match the battery bay exactly, and the BMS communicates with the XPR-5522GMX driver circuit to enable mode control and low-voltage protection.
• Bench tested on actual hardware: We cycled this cell through charge, discharge, and all output modes on the XPR-5522GMX. The BMS held the correct cutoff voltage under turbo draw, and the driver stepped down output cleanly at low-cell threshold without tripping a hard shutdown.
• Single-cell care on this light: The XPR-5522GMX runs one cell. If you use a partially depleted spare alongside this new battery at different times without full cycling in between, the driver will see inconsistent voltage on startup and may default to reduced output — always fully charge this cell before first deployment.

Why the XPR-5522GMX steps down brightness before the low-battery indicator fires

The XPR-5522GMX driver runs a constant-current circuit that monitors cell voltage continuously. When the cell drops below the driver's brownout threshold — typically around 3.0V under load — the driver cuts current to the LEDs to protect the cell, even if the battery indicator hasn't triggered yet. This is intentional protection behaviour, not a fault. The indicator trips slightly later because it reads resting voltage, not loaded voltage. If the light dims noticeably in turbo before any warning, the cell is near end of charge.

XPR-5522GMX flickering or cycling between modes near end of charge

When the cell voltage sags under high-current draw, the driver may oscillate — briefly cutting power, the cell voltage recovers, power resumes, then sags again. This produces a flicker or appears as the light cycling modes on its own. It is not a driver fault or a defective battery. Switch to a lower output mode immediately — this reduces current draw, stops the voltage sag cycle, and lets you finish the task before recharging. Recharge when the cell reaches 3.0V resting.