{"product_id":"nightstick-xpr-5580-replacement-battery-37v-5200mah-li-ion","title":"Nightstick XPR-5580 Replacement Battery 3.7V 5200mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eNightstick XPR-5580 \/ XPR-5581RX \/ XPR-5542GMX — 3.7V Li-ion Replacement Battery (5500-BATT)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is the OEM-equivalent 3.7V Li-ion cell for the Nightstick XPR-5580, XPR-5581RX, and XPR-5542GMX tactical flashlights. It matches the original 5500-BATT specification at 5200mAh (19.24Wh). These lights are used by law enforcement and emergency responders, so a weak cell is not a minor inconvenience.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eXPR-5580 series fit:\u003c\/strong\u003e All three listed models share the same battery bay geometry, cell voltage, and driver communication protocol. The flashlight driver reads cell state directly — wrong voltage or a mismatched BMS response will cause the driver to default to a reduced output mode before the battery indicator shows low.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e We cycled this cell through the XPR-5580's full output modes including turbo. The BMS held the 3.7V nominal rail without false low-voltage cutoff during high-current draw spikes, and the protection circuit triggered correctly at the lower discharge threshold.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eTurbo mode storage caution:\u003c\/strong\u003e Storing this light after extended turbo sessions with the cell still warm accelerates electrolyte stress. Let the cell return to ambient temperature before capping and storing the light — turbo draw generates more internal heat than standard or low modes.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the XPR-5580 steps down output before the battery indicator reads low\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe XPR-5580 driver monitors cell voltage in real time and applies brownout protection before the fuel gauge threshold triggers. As the cell voltage sags under high-current draw — especially in turbo — the driver steps output down to protect the cell and maintain a stable arc. This is normal circuit behaviour, not a fault. A degraded or partially discharged cell will trigger this step-down earlier and more frequently. Replacing the cell with a fresh 5200mAh unit restores the full output window before brownout kicks in.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eFlashlight driver cycling through modes or flickering at end of charge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eIf the XPR-5580 begins rapidly cycling modes or flickering near the end of a charge, the driver is hitting the brownout threshold repeatedly as the cell voltage oscillates under load. This is distinct from a dead cell — the battery still has charge, but voltage is dropping below the driver's minimum under draw and recovering at rest. Switch to a lower output mode immediately to stop the cycling and draw down the remaining charge safely. Once recharged with a healthy cell, this behaviour stops; if it continues on a fresh charge, check the charger contact pins for corrosion.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43377498259546,"sku":"BWCS-NXP550FT-1","price":39.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43377498292314,"sku":"BWCS-NXP550FT-2","price":46.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43377498325082,"sku":"BWCS-NXP550FT-3","price":51.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NXP550FT-1.webp?v=1778767205","url":"https:\/\/batteryweb.com\/products\/nightstick-xpr-5580-replacement-battery-37v-5200mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}