{"product_id":"fly-ds120-replacement-battery-37v-1300mah-li-ion","title":"Fly DS120 Replacement Battery BL6203 3.7V 1300mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eFly DS120 — 3.7V Li-ion Replacement Battery (BL6203)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 1300mAh Li-ion replacement battery for the Fly DS120 smartphone. It carries OEM part number BL6203 and slots directly into the DS120's battery bay. Capacity figure is 4.81Wh.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eDS120 platform fit:\u003c\/strong\u003e\n    The DS120 uses a compact 60.00 × 43.80 × 4.50mm cell running at 3.7V nominal. This replacement matches that voltage rail and physical footprint, so the phone's power management IC sees the same parameters as the original BL6203.\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 DS120 unit. The BMS accepted the charge handshake without fault flags, and the protection circuit tripped correctly at the low-voltage cutoff threshold — no thermal events recorded.\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 gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes load 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\"\u003eSudden shutdown at 20–30% on the DS120 after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe DS120's fuel gauge IC holds a discharge curve learned from the original cell. When a new cell goes in, the stored curve no longer matches actual cell behaviour, and the phone miscalculates remaining capacity. Under modem or screen load — both high-current draws — the new cell's voltage drops faster than the IC expects, and the phone hits its emergency cutoff while still reporting 20–30% remaining. One full discharge-charge cycle without fast charging resets the coulomb counter and lets the IC relearn the curve against the new cell.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBattery percentage jumping erratically on the DS120\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eErratic percentage readings on the DS120 — jumping from 45% to 60% or dropping 15% in seconds — point to the fuel gauge IC recalibrating against a new cell it has not yet fully characterised. This is not a fault with the replacement cell itself. Drain the battery until the phone shuts off automatically, then charge uninterrupted to 100% with the screen on as little as possible. After one complete cycle, readings stabilise at the correct voltage-to-percentage mapping, typically within ±3%.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404278399066,"sku":"BWCS-DEP571SL-1","price":22.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404278431834,"sku":"BWCS-DEP571SL-2","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404278464602,"sku":"BWCS-DEP571SL-3","price":27.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-DEP571SL-1.webp?v=1779369550","url":"https:\/\/batteryweb.com\/products\/fly-ds120-replacement-battery-37v-1300mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}