{"product_id":"bci-capnocheck-ii-capnograph-pulse-oximeter-replacement-battery-74v-3400mah-li-ion","title":"BCI MCR-1821J\/1-H Capnocheck II Compatible Battery 7.4V 3400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eBCI Capnocheck II Capnograph Pulse Oximeter — 7.4V Li-ion Replacement Battery (MCR-1821J\/1-H)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 7.4V 3400mAh Li-ion battery replaces the OEM pack in the BCI Capnocheck II Capnograph Pulse Oximeter and compatible Capnocheck 8400 and 8401 units. It supports simultaneous end-tidal CO₂ and SpO₂ monitoring during patient assessments and transport. Voltage and capacity match OEM specifications to satisfy the device's BMS handshake on startup.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCapnocheck II, 8400, and 8401 compatibility:\u003c\/strong\u003e\n    These models share the same 7.4V battery rail, connector pinout, and BMS communication protocol. A single pack services the full range without any adapter or modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this pack on a Capnocheck II under simultaneous capnography and oximetry load. The BMS completed its initialisation handshake, accepted the charge IC communication, and passed the device's internal self-test without triggering a battery fault code.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-swap startup protocol:\u003c\/strong\u003e\n    After installing this battery, allow the Capnocheck to complete its full power-on self-test cycle without interruption. The BMS runs a verification sequence at startup — cutting power during this window forces a false battery fault that persists until a clean reboot clears it.\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 alarms low battery immediately after a confirmed full charge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Capnocheck II's charge IC applies a conservative current limit to cells it has not yet profiled. On the first charge cycle, the BMS may not register the pack as fully qualified, so the device flags a low-battery condition even when the cell is at full voltage. This is not a fault in the replacement pack — it is the BMS running a learn cycle. Complete one full charge-to-discharge-to-charge cycle, and the alarm clears. After that cycle, the device should recognise the pack and report charge level accurately.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eDevice will not power on after the battery sat in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLi-ion cells self-discharge at roughly 1–3% per month. A pack that shipped or stored for several months can drop below the BMS recovery threshold — typically around 2.5V per cell — and the device will show no response at all when the power button is pressed. The BMS enters a protection state at that voltage and blocks the discharge path entirely. Connect the battery to the OEM charger and leave it for a minimum of two hours before attempting to power on the device; most BMS circuits allow a slow recovery charge from as low as 2.0V per cell before re-enabling the output.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43381469937754,"sku":"BWCS-BCM200MX-1","price":38.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43381469970522,"sku":"BWCS-BCM200MX-2","price":44.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43381470003290,"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\/bci-capnocheck-ii-capnograph-pulse-oximeter-replacement-battery-74v-3400mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}