{"product_id":"srf-startrail-2-replacement-battery-37v-1200mah-li-ion","title":"SRF StarTrail 2 Replacement Battery 3.7V 1200mAh Li-ion","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSRF StarTrail 2 — 3.7V Li-ion 1200mAh Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V Li-ion cell rated at 1200mAh (4.44Wh), sized as a direct physical fit for the SRF StarTrail 2 smartphone. It replaces a degraded or failed original cell that can no longer hold a usable charge. Dimensions are 49.50 × 44.20 × 4.50mm — confirm against your existing cell before fitting.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eStarTrail 2 cell compatibility:\u003c\/strong\u003e\n    The StarTrail 2 uses a compact 3.7V single-cell configuration with a low-current BMS that matches this cell's charge termination voltage and protection thresholds. Swapping in a mismatched cell chemistry or higher voltage can trip the charge IC permanently.\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 under screen-on and modem-active loads. The BMS held protection thresholds correctly and charge termination occurred at the expected 4.2V cutoff without anomalies.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the StarTrail 2 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe StarTrail 2 uses a coulomb-counting fuel gauge IC that builds its reference model from the original cell's discharge curve. When a new cell goes in, that stored model no longer matches actual cell behaviour. The IC will show inflated or deflated percentages until it completes at least one full charge-to-discharge cycle. Run the phone from 100% down to automatic shutdown, then charge uninterrupted to 100% — one complete cycle resets the reference model.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% charge remaining on the replacement cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the cell voltage drops sharply under load — typically during screen brightness peaks or mobile data bursts — faster than the fuel gauge IC predicted from its uncalibrated model. The phone's low-voltage protection trips before the displayed percentage reaches zero. It is not a faulty cell. Complete one full calibration cycle as described above, and the IC will map the new cell's actual voltage cliff and adjust shutdown timing to match real remaining capacity.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405077151834,"sku":"BWCS-HU8650SL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405077184602,"sku":"BWCS-HU8650SL-2","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405077217370,"sku":"BWCS-HU8650SL-3","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-HU8650SL-1.webp?v=1779369919","url":"https:\/\/batteryweb.com\/products\/srf-startrail-2-replacement-battery-37v-1200mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}