{"product_id":"doro-6821-replacement-battery-37v-1200mah-li-ion","title":"Doro 6821 Replacement Battery 3.7V 1200mAh 380147","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eDoro 6821 \/ 6881 Series — 3.7V Li-ion Replacement Battery (380147)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V 1200mAh Li-ion battery for the Doro 6821 and related models including the 6881, 1370, and 1372. It replaces OEM part numbers 380147, DBAA-1000A, and DBO-1000A. These are senior-friendly mobile phones where a degraded battery directly impacts emergency call availability.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eDoro 6821 \/ 6881 \/ 1370 \/ 1372 fit group:\u003c\/strong\u003e\n    These models share the same 3.7V single-cell architecture, physical footprint (53.00 × 33.90 × 5.70mm), and connector pinout. The BMS handshake requirements are identical across the range, so one cell covers all listed variants 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 charge and discharge on compatible Doro hardware. The BMS accepted the charge IC handshake on the first cycle, held the cutoff voltage cleanly at 4.2V, and showed no fault flags during a full-depth discharge.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after swap:\u003c\/strong\u003e\n    On first use after fitting, run one complete discharge to around 10%, then charge to 100% without interruption. This gives the fuel gauge IC a full reference cycle against the new cell's discharge curve before the OS starts drawing on cached data from the old cell.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Doro 6821 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe fuel gauge IC in the Doro 6821 tracks charge state using a coulomb counter calibrated to the original cell's discharge curve. When you fit a new cell, the counter still references the old curve, so percentage readings can be off by 15–25% until recalibration occurs. The IC recalibrates by observing a full discharge-to-charge cycle on the new cell. One complete cycle — down to the low-battery cutoff, then a full uninterrupted charge to 100% — resets the reference curve and brings percentage readings back into line.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% on the replacement cell\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the cell voltage drops sharply under load — the modem transmitting or the screen at full brightness — faster than the fuel gauge IC expects. The BMS hits the low-voltage cutoff, typically around 3.0V per cell, and shuts the phone down even though the displayed percentage suggests charge remains. It is a fuel gauge calibration issue, not a faulty cell. Run one full discharge-charge cycle without interruption and the shutdowns should stop as the IC recalibrates its voltage-to-percentage mapping.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43391924240474,"sku":"BWCS-DEP240SL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43391924273242,"sku":"BWCS-DEP240SL-2","price":27.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43391924306010,"sku":"BWCS-DEP240SL-3","price":29.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-DEP240SL-1.webp?v=1779142676","url":"https:\/\/batteryweb.com\/products\/doro-6821-replacement-battery-37v-1200mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}