{"product_id":"fly-iq449-replacement-battery-37v-1400mah-li-ion","title":"Fly IQ449 Replacement Battery BL7405 3.7V 1400mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eFly IQ449 — 3.7V Li-ion Replacement Battery (BL7405)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThe BL7405 is a 3.7V Li-ion cell rated at 1400mAh (5.18Wh), built to fit the Fly IQ449 smartphone. It slots directly into the IQ449's battery bay and connects to the same three-pin contact strip as the original. Voltage and physical dimensions match the OEM spec: 57.70 × 51.80 × 4.65mm.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eIQ449 fitment:\u003c\/strong\u003e\n    The IQ449 uses the BL7405 form factor — a flat Li-ion cell with a specific contact layout tied to this handset's charge IC. The connector pin-out and cell thickness must match exactly, or the battery door won't close and the charge circuit won't engage.\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 IQ449 platform and confirmed the BMS handshake with the phone's charge IC. Charge acceptance was normal from the first cycle, and the protection circuit tripped correctly at low-voltage cutoff.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    On first installation, disable fast charging if the option is available, then run one full discharge-to-charge cycle before normal use. This lets the fuel gauge IC map its coulomb counter to the new cell's discharge curve before high-current charging begins on 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 IQ449 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe IQ449's fuel gauge IC stores a learned discharge curve from the old cell. When a new cell goes in, the stored curve no longer matches the actual cell chemistry, so the percentage readout drifts. The IC needs at least one complete discharge and charge cycle to re-anchor its coulomb counter to the new cell. Until that cycle completes, the displayed percentage can read 10–15% higher or lower than the true state of charge.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% on the IQ449 after replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the fuel gauge IC is still calibrated to the old cell's voltage curve and the phone's modem or display draws a current spike the new cell can't sustain at that state of charge. The cell voltage sags below the protection threshold under load, triggering an immediate shutdown even though the displayed percentage looks safe. It is not a faulty cell — it is a calibration gap. Run one full discharge to auto-off, then charge uninterrupted to 100%, and the shutdowns will stop.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404131532890,"sku":"BWCS-FIQ449SL-1","price":23.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404131565658,"sku":"BWCS-FIQ449SL-2","price":26.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404131598426,"sku":"BWCS-FIQ449SL-3","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-FIQ449SL-1.webp?v=1779369037","url":"https:\/\/batteryweb.com\/products\/fly-iq449-replacement-battery-37v-1400mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}