{"product_id":"streamlight-stylus-pro-cob-replacement-battery-37v-640mah-li-ion","title":"Streamlight Stylus Pro COB 66143 3.7V Replacement Battery","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eStreamlight Stylus Pro COB \/ Stylus Pro USB — 3.7V Li-ion Replacement Battery (66143)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V 640mAh Li-ion cell replaces the factory battery in the Streamlight Stylus Pro COB and Stylus Pro USB flashlights. Both lights run a single-cell configuration, so this is a direct swap once the original cell degrades. Capacity figure is 640mAh (2.37Wh) — use that number when comparing against third-party cells.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eStylus Pro COB and USB compatibility:\u003c\/strong\u003e\n    Both models share the same single-cell bay, voltage rail, and driver board. The COB uses a chip-on-board emitter array; the USB variant adds an onboard charging circuit. Neither requires BMS handshake authentication, so the cell seats and powers up without firmware intervention.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through full charge and discharge on the Stylus Pro COB driver. The BMS held cutoff at 2.75V under load and accepted a full charge termination at 4.2V without deviation across three consecutive cycles.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eUSB model charging port caution:\u003c\/strong\u003e\n    On the Stylus Pro USB, charge the battery inside the light via the built-in micro-USB port only. Charging the bare cell externally on a generic charger bypasses the light's onboard protection circuit and can push voltage past the cell's rated ceiling.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eStylus Pro COB dimming before the battery reads empty\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe COB driver uses brownout protection that steps output down before the cell actually hits cutoff. This is intentional — the driver reduces current draw to keep voltage above 3.0V and protect the cell from a hard drop. Users often see noticeable dimming at around 30–40% of remaining capacity. Stepping down to a lower output mode at that point lets the driver stabilise and extends usable light before the cell fully depletes.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eReplacement cell not reaching full brightness after first charge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eA new Li-ion cell sometimes shows reduced output on the first one or two cycles because the electrodes haven't reached full ionic mobility yet. This isn't a faulty cell — it's normal formation behaviour. Run two full charge-discharge cycles and output should normalise. If brightness is still noticeably low after the second cycle, check resting cell voltage with a multimeter: a healthy fully-charged cell should read between 4.15V and 4.20V.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43377470144602,"sku":"BWCS-SLX661FT-1","price":36.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43377470177370,"sku":"BWCS-SLX661FT-2","price":42.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43377470210138,"sku":"BWCS-SLX661FT-3","price":47.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-SLX661FT-1.webp?v=1778767172","url":"https:\/\/batteryweb.com\/products\/streamlight-stylus-pro-cob-replacement-battery-37v-640mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}