{"product_id":"nightstick-xpr-5580-replacement-battery-37v-6800mah-li-ion","title":"Nightstick XPR-5580 Replacement Battery 3.7V 6800mAh","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 a 3.7V 6800mAh lithium-ion replacement battery for the Nightstick XPR-5580, XPR-5581RX, and XPR-5542GMX tactical flashlights. It uses OEM part number 5500-BATT and fits the cylindrical single-cell format these lights require. Capacity is 25.16Wh — matched to the product data, not estimated.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eXPR-5580 \/ XPR-5581RX \/ XPR-5542GMX platform fit:\u003c\/strong\u003e\n    All three models share the same cell format, voltage rail, and driver interface. The 5500-BATT cell slots into each without modification — same connector, same BMS voltage thresholds, same physical dimensions at 139.30 × 24.00 × 24.00mm.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through full charge-discharge cycles on the XPR-5580 driver board. The BMS held cutoff at the correct low-voltage threshold and did not trip prematurely during turbo-mode draw spikes.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eTurbo mode draw and cell stress:\u003c\/strong\u003e\n    Turbo mode on the XPR-5580 pulls significantly higher current than standard or low modes. Keep the light body clear of obstructions during extended turbo use — heat buildup at the head transfers back to the cell and accelerates capacity fade over time.\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 uses brownout protection that reduces lumen output before the cell actually reaches low-voltage cutoff. This is intentional — the driver detects voltage sag under load, not resting voltage, so it steps down to protect the cell under high-current draw. The battery indicator reads the resting voltage, which still looks acceptable. If you see output step down on turbo or high mode, switch to a lower mode — the cell still has usable charge, just not enough headroom to sustain peak draw.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eFlashlight cycling through modes or flickering near end of charge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eMode-cycling or rapid flicker near the end of a charge cycle is the driver repeatedly tripping and recovering as cell voltage dips below the brownout threshold under load, then recovers at rest. This is not a faulty battery or driver — it signals the cell is nearly depleted. Stop using the light and recharge immediately. A healthy replacement cell should show a resting voltage of 3.6–3.7V off the charger before first use — verify with a multimeter if the light exhibits this behaviour from day one.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43377497571418,"sku":"BWCS-NXP551FT-1","price":42.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43377497604186,"sku":"BWCS-NXP551FT-2","price":49.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43377497636954,"sku":"BWCS-NXP551FT-3","price":54.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-NXP551FT-1.webp?v=1778767205","url":"https:\/\/batteryweb.com\/products\/nightstick-xpr-5580-replacement-battery-37v-6800mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}