{"product_id":"bq-aquaris-m55-replacement-battery-38v-3400mah-li-polymer","title":"BQ Aquaris M5.5 Replacement Battery 3.8V 3400mAh 3620","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eBQ Aquaris M5.5 — 3.8V Li-Polymer Replacement Battery (3620)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.8V, 3400mAh Li-Polymer cell for the BQ Aquaris M5.5 smartphone, cross-referenced to OEM part number 3620. It fits the internal battery bay of the M5.5 directly. If your phone shuts down unexpectedly, won't hold charge, or fails to power on, this cell addresses those fault conditions.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eAquaris M5.5 fitment:\u003c\/strong\u003e\n    The M5.5 uses a fixed connector orientation and a BMS that negotiates directly with the phone's charge IC. This cell matches the connector pinout, the physical envelope (82.40 × 66.40 × 4.00 mm), and the voltage rail the board expects.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran charge-discharge cycles through the BMS and confirmed the protection circuit triggers correctly at low-voltage cutoff. The fuel gauge IC accepted the cell without throwing a fault flag after a full calibration cycle.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after swap:\u003c\/strong\u003e\n    On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging is applied to an uncalibrated 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 Aquaris M5.5 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe M5.5 uses a coulomb counter that builds its fuel map against the original cell's impedance and discharge curve. When you install a new cell, the counter still references the old curve, so the percentage readout drifts — often showing full charge until the voltage drops suddenly. One complete slow-charge cycle forces the IC to re-learn the new cell's characteristics. After that cycle, percentage accuracy stabilises and the readout tracks the actual state of charge correctly.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% remaining on the replacement cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the modem or display draws a peak current the cell can't sustain at low state-of-charge, causing the terminal voltage to sag below the BMS cutoff threshold — even though the reported percentage still looks safe. The fuel gauge hasn't recalibrated yet, so it's reporting a percentage that doesn't match the real voltage. Run one full discharge down to automatic shutdown, then charge uninterrupted to 100%. After that cycle, the coulomb counter anchors its low-end threshold correctly and the early shutdowns stop.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43392070090842,"sku":"BWCS-BQM550SL-1","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43392070123610,"sku":"BWCS-BQM550SL-2","price":28.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43392070156378,"sku":"BWCS-BQM550SL-3","price":31.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BQM550SL-1.webp?v=1779143561","url":"https:\/\/batteryweb.com\/products\/bq-aquaris-m55-replacement-battery-38v-3400mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}