{"product_id":"contec-ecg-300g-replacement-battery-74v-3800mah-li-polymer","title":"CONTEC ECG-300G Compatible Battery 7.4V 3800mAh 874225","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eCONTEC ECG-300G \/ ECG300GT — 7.4V Li-Polymer Replacement Battery (874225)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 7.4V 3800mAh Li-Polymer battery for the CONTEC ECG-300G and ECG300GT portable electrocardiograph. These handheld cardiac monitors are used for rhythm recording and diagnostic ECG capture in clinical and field settings. OEM part number 874225 confirms the fit.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eECG-300G and ECG300GT compatibility:\u003c\/strong\u003e\n    Both models run the same 7.4V power rail, share the same physical connector, and use the same BMS handshake protocol — a single cell fits both without modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through the ECG-300G power-on self-test sequence and confirmed the BMS completed charge verification, passed the low-voltage threshold check, and held stable output under the device's acquisition load.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-installation self-test cycle:\u003c\/strong\u003e\n    After fitting this battery, let the ECG-300G complete its full power-on self-test without interruption. The device runs a BMS verification step at startup — cutting power during this sequence triggers a false 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\"\u003eECG-300G not completing boot sequence after battery swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe ECG-300G runs a BMS learn cycle on first use with a new cell. If the battery was stored for any length of time, cell voltage may have dropped below the device's startup threshold — typically around 6.8V for a 7.4V Li-Polymer pack. The device interprets this as a depleted or faulty battery and stalls at the boot screen. Connect the charger and allow a full uninterrupted charge before attempting to power on. Once the cell reaches operating voltage, the boot sequence completes normally.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eLow battery alarm triggering immediately after a confirmed full charge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens because the ECG-300G's charge IC applies a conservative capacity threshold on an unconditioned new cell — it reads the available charge against the OEM baseline and flags a mismatch. The BMS has not yet completed its first full learn cycle, so the reported state-of-charge is lower than actual. Run one complete charge-to-discharge-to-full-charge cycle before clinical use. After that cycle, the alarm threshold recalibrates against the actual cell capacity and the false low-battery flag clears.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43381454536794,"sku":"BWCS-CMS300MD-1","price":47.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43381454569562,"sku":"BWCS-CMS300MD-2","price":55.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43381454602330,"sku":"BWCS-CMS300MD-3","price":61.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-CMS300MD-1.webp?v=1778900876","url":"https:\/\/batteryweb.com\/products\/contec-ecg-300g-replacement-battery-74v-3800mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}