{"product_id":"fossil-q-marshal-gen-4-replacement-battery-38v-330mah-li-polymer","title":"Fossil APP00276 Q Marshal Gen 4 Smartwatch Replacement Battery 3.8V 330mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eFossil Q Marshal Gen 4 — 3.8V Li-Polymer Replacement Battery (APP00276)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.8V, 330mAh Li-Polymer cell is a direct swap for the original APP00276 battery in the Fossil Q Marshal Gen 4 smartwatch. It fits the 29.60 x 24.00 x 3.80mm battery bay and matches the original connector pinout. Replace this when the watch can no longer hold a charge through a full day of normal use.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eQ Marshal Gen 4 fitment:\u003c\/strong\u003e\n    The Gen 4 platform uses a BMS handshake tied to this cell's impedance profile. Swapping to a cell of the correct voltage and capacity keeps the fuel gauge IC reading accurately and prevents false low-battery shutdowns.\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 the Q Marshal Gen 4 board. The BMS accepted the new cell without error flags, and the fuel gauge recalibrated correctly after a full charge from near-zero.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-swap charge requirement:\u003c\/strong\u003e\n    After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before first use. The fuel gauge IC on the Q Marshal Gen 4 loses its reference point during a cell swap and cannot recalibrate without a full charge cycle starting from near-zero.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Q Marshal Gen 4 shows 0% immediately after a battery swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Q Marshal Gen 4 uses a coulomb-counting fuel gauge IC that tracks charge state relative to a known baseline. When you remove the old cell, that baseline is wiped. The watch reports 0% — or refuses to boot — because the IC has no reference point, not because the new cell is flat. Fit the battery, connect the charger, and let it reach 100% without interruption. The IC re-establishes its reference at full charge, and the percentage display returns to normal from that point forward.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBattery draining in one day instead of multi-day on the Q Marshal Gen 4\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eAlways-on display mode combined with continuous heart rate monitoring pulls a sustained current that a 330mAh cell was not sized to sustain for multiple days. Check Wear OS settings and confirm that always-on display and continuous HR tracking are both turned off — tilt-to-wake and on-demand HR extend charge intervals significantly. If drain remains heavy after those changes, check that no background app is holding a persistent BLE connection. Under typical notification and step-tracking use, charge level should remain above 20% at end of day.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43416153096282,"sku":"BWCS-FTL276SH-1","price":38.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43416153129050,"sku":"BWCS-FTL276SH-2","price":45.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43416153161818,"sku":"BWCS-FTL276SH-3","price":49.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-FTL276SH-1.webp?v=1779760505","url":"https:\/\/batteryweb.com\/products\/fossil-q-marshal-gen-4-replacement-battery-38v-330mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}