{"product_id":"zte-q705u-replacement-battery-38v-2500mah-li-polymer","title":"ZTE Q705U Li-Polymer Replacement Battery 3.8V 2500mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eZTE Q705U \/ Grand SII Series — 3.8V Li-Polymer Replacement Battery (Li3825T43P6H755543)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.8V, 2500mAh (9.5Wh) Li-Polymer battery for the ZTE Q705U, Grand SII, S221, and S251 smartphones. It replaces OEM part Li3825T43P6H755543 directly. Swap it when the original cell no longer holds a charge or shuts the phone down unexpectedly.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eQ705U and Grand SII series compatibility:\u003c\/strong\u003e\n    These models share the same 3.8V single-cell power rail, the same physical connector pinout, and the same BMS handshake protocol — one cell fits the full group without modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell on a Q705U through full charge and load discharge. The BMS held charge termination at 4.35V and triggered low-voltage cutoff cleanly at 3.0V with no false trips during modem-load spikes.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle fast charge tip:\u003c\/strong\u003e\n    On first use after installation, disable fast charging and run one complete discharge-charge cycle. This lets the fuel gauge IC map 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\"\u003eSudden shutdown at 20–30% on the ZTE Q705U after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Q705U's fuel gauge IC stores a charge curve calibrated to the old, degraded cell. When you install a fresh cell, the IC doesn't yet know where that cell's voltage cliff sits. Under modem or screen load, the new cell's voltage briefly sags — the IC reads that as empty and cuts power even though capacity remains. One full discharge-charge cycle rewrites the stored curve. After that cycle, the percentage display and actual cutoff voltage align correctly.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eOS reporting wrong battery percentage after replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe coulomb counter inside the Q705U recalibrates against the last known discharge curve — which belongs to the old cell. A new 2500mAh Li-Polymer cell has a different impedance profile, so the percentage can jump or freeze at points like 60% or 15%. Drain the phone fully until it shuts off on its own, then charge uninterrupted to 100% without unplugging early. One clean cycle resets the counter to the new cell's actual curve.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43404240388186,"sku":"BWCS-ZTU705XL-1","price":24.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43404240420954,"sku":"BWCS-ZTU705XL-2","price":27.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43404240453722,"sku":"BWCS-ZTU705XL-3","price":30.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-ZTU705XL-1.webp?v=1779369465","url":"https:\/\/batteryweb.com\/products\/zte-q705u-replacement-battery-38v-2500mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}