Nightstick XPR-5522GMX Replacement Battery 3.7V 2600mAh

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

This 3.7V 2600mAh Li-ion cell replaces the OEM 5522-BATT in the Nightstick XPR-5522GMX dual-light tactical flashlight. The XPR-5522GMX combines a high-intensity LED beam with a red warning light, drawing variable current depending on which mode and output level is active. Capacity figure is 2600mAh (9.62Wh) as specified in the product data.

• XPR-5522GMX platform fit: The 5522-BATT cell is specific to the XPR-5522GMX's internal bay dimensions and connector orientation. The flashlight's driver board reads cell voltage directly to manage output stepping — any cell outside the correct voltage range causes the driver to drop output early or refuse to enter turbo mode at all.
• Bench tested on actual hardware: We cycled this cell through full discharge at high-draw loads and confirmed the BMS held voltage above the driver's brownout threshold through multiple mode transitions. The protection circuit cut cleanly at low-voltage limit without tripping mid-cycle on standard or strobe modes.
• Turbo mode draw management: Turbo mode on the XPR-5522GMX pulls significantly higher current than standard or low modes. After heavy turbo use, allow the cell to cool before recharging — charging a thermally stressed Li-ion cell accelerates capacity fade over subsequent cycles.

Why the XPR-5522GMX steps down output before the indicator signals low

The XPR-5522GMX's driver uses a brownout protection threshold that sits above the cell's actual low-voltage cutoff. When cell voltage drops under sustained high-draw output, the driver reduces brightness to protect the LED and cell before the battery indicator triggers. This is intentional driver behaviour, not a cell fault. If the light dims noticeably during turbo use but recovers on a lower mode, the cell voltage is sagging under load — normal as a Li-ion cell ages and internal resistance rises. A fresh replacement cell will hold voltage above that threshold longer across the draw curve.

Flashlight cycling through modes on its own near end of charge

If the XPR-5522GMX begins switching modes or flickering without input near the end of a charge cycle, the driver is hitting its brownout threshold repeatedly as the cell voltage hovers at the cutoff edge. The cell isn't failing — the driver is doing exactly what it's programmed to do. Switch the light to a lower output mode manually; this reduces current draw enough to keep voltage stable above the cutoff point. If the behaviour starts occurring earlier in a charge cycle over time, internal resistance in the existing cell has risen — replace the cell and verify the new one holds above 3.5V under load.