{"product_id":"navon-t400-replacement-battery-37v-1200mah-li-ion","title":"Navon T400 Replacement Battery 3.7V 1200mAh Li-ion","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eNavon T400 — 3.7V Li-ion Replacement Battery (T400)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V 1200mAh Li-ion cell for the Navon T400 smartphone. It replaces the original battery when the cell has degraded, swells, or no longer holds a usable charge. Dimensions are 60.70 × 50.10 × 4.24mm — confirm these against your existing cell before installing.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eNavon T400 fitment:\u003c\/strong\u003e\n    The T400 uses a compact removable Li-ion cell with a low 3.7V nominal rail. The connector pinout and BMS communication lines match the original cell, so the phone's charge IC recognises the battery on first boot.\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 a controlled rig. The BMS engaged protection at the expected cutoff voltage and resumed charging cleanly after a rest period. No anomalous heat or voltage drop was recorded.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after swap:\u003c\/strong\u003e\n    On first use after installation, run one full discharge to auto-off then charge uninterrupted to 100% before using the phone normally. This gives the fuel gauge IC a complete reference curve against the new cell — skipping it causes percentage jumps and early shutdowns.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the T400 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe T400's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The chip reads voltage and maps it to a percentage using old data, so it shows numbers that are off by 10–20%. One complete discharge-charge cycle overwrites the reference and the gauge reads accurately from that point forward.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% 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 modem activity, screen-on bursts, or app CPU spikes. The phone's protection circuit triggers a shutdown before the displayed percentage reaches zero because the cell cannot sustain voltage above the 3.0V cutoff under that load. It is not a faulty battery — it is an uncalibrated fuel gauge reading a fresh cell. Run one full discharge cycle to 0% auto-off, then charge to 100%, and the shutdowns will stop.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43392036044890,"sku":"BWCS-BLA090SL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43392036077658,"sku":"BWCS-BLA090SL-2","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43392036110426,"sku":"BWCS-BLA090SL-3","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BLA090SL-1.webp?v=1779143085","url":"https:\/\/batteryweb.com\/products\/navon-t400-replacement-battery-37v-1200mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}