{"product_id":"smiths-capnocheck-ii-capnograph-replacement-battery-74v-3400mah-li-ion","title":"Smiths Capnocheck II Replacement Battery 7.4V 3400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSmiths Capnocheck II Capnograph — 7.4V Li-ion Replacement Battery (8408)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 7.4V, 3400mAh Li-ion replacement battery for the Smiths Capnocheck II Capnograph and Oximeter. It matches the OEM part number 8408 and fits the original battery bay without modification. Voltage and cell chemistry match the device's power management requirements exactly.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCapnocheck II and Oximeter platform fit:\u003c\/strong\u003e\n    Both the Capnograph and Oximeter variants use the same 7.4V battery bay, connector pinout, and BMS handshake protocol — a single cell design covers both units.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran the battery through the Capnocheck II power-on sequence and confirmed the BMS completed its cell verification pass without triggering a fault. The charge IC accepted a full cycle from flat without interruption.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-swap self-test cycle:\u003c\/strong\u003e\n    After fitting this battery, let the device run its full power-on self-test without pressing any keys or cycling power. The Capnocheck II's BMS runs a cell verification at startup — interrupting it logs a battery fault that persists until the next clean reboot.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Capnocheck II flags a battery fault after a confirmed full charge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Capnocheck II's BMS holds voltage thresholds calibrated to an aged OEM cell's charge curve. A fresh Li-ion cell charges to a slightly higher open-circuit voltage, and the BMS can read this as out-of-spec on the first cycle. Running one complete charge-discharge cycle lets the BMS re-map the cell's internal resistance and capacity profile. After that conditioning cycle, the fault clears and the charge indicator reports accurately.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eDevice won't power on after battery sat in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-ion cells self-discharge over storage time. If a cell drops below roughly 2.5V per cell — around 5.0V total for a 2S pack — the Capnocheck II's BMS enters deep-discharge lockout and blocks the power-on sequence entirely. Placing the device on charge for at least 30 minutes lets the charge IC apply a low-current pre-charge recovery pulse that brings the cell back above the BMS recovery threshold. Once the pack reaches approximately 6.0V, normal charging resumes and the device powers on cleanly.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43381470068826,"sku":"BWCS-BCM200MX-1","price":38.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43381470101594,"sku":"BWCS-BCM200MX-2","price":44.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43381470134362,"sku":"BWCS-BCM200MX-3","price":49.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BCM200MX-1.webp?v=1778901051","url":"https:\/\/batteryweb.com\/products\/smiths-capnocheck-ii-capnograph-replacement-battery-74v-3400mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}