{"product_id":"sony-ericsson-xperia-u-replacement-battery-37v-1300mah-li-ion","title":"BA600 Sony Ericsson Xperia U Replacement Battery 3.7V 1300mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSony Ericsson Xperia U \/ ST25i — 3.7V Li-ion Replacement Battery (BA600)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 1300mAh Li-ion replacement cell for the Sony Ericsson Xperia U (ST25, ST25i, Kumquat). It replaces OEM part number BA600 directly. When the original cell degrades and the phone starts shutting down unexpectedly or refusing to hold charge, this is the swap.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eST25 and ST25i compatibility:\u003c\/strong\u003e\n    Both ST25 variants use the same battery bay dimensions, connector pinout, and BMS handshake as the Xperia U. The BA600 footprint — 64.10 × 43.90 × 4.00mm — is shared across that entire compact platform, so the cell seats and communicates correctly on all listed models.\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 an ST25i unit. The BMS accepted the charge IC handshake without error, held voltage above 3.6V through the mid-discharge range, and tripped the low-voltage cutoff at the correct threshold rather than dropping the phone unexpectedly.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    After fitting this cell, disable any fast-charge mode for the first full discharge-charge cycle. The fuel gauge IC on the ST25 is calibrated to the old cell's discharge curve. Running one slow cycle first lets the coulomb counter re-anchor to the new cell before high-current charging begins.\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 Xperia U after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThis is a voltage cliff issue, not a capacity problem. Under peak load — mobile data, screen-on, or audio playback simultaneously — the new cell draws enough current to pull its terminal voltage below the shutdown threshold even when the reported state-of-charge still looks healthy. The fuel gauge IC is working from a stale discharge curve mapped to the old, degraded cell. One full discharge down to automatic shutdown, followed by an uninterrupted charge to 100%, resets the coulomb counter reference and typically resolves the premature cutoff.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003ePhone shows wrong battery percentage after installing the BA600\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe ST25i stores the previous cell's discharge profile in the fuel gauge IC. A new cell with a tighter, steeper discharge curve will read as either artificially high or drop percentage in large jumps. This is not a fault with the replacement cell — it is the gauge reporting against the wrong reference map. Force a full discharge until the phone powers off on its own, then charge uninterrupted to 100% without removing the charger. After that single cycle, percentage reporting should track within a few points of actual remaining capacity.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405022527578,"sku":"BWCS-ERA600XL-1","price":28.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405022560346,"sku":"BWCS-ERA600XL-2","price":32.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405022593114,"sku":"BWCS-ERA600XL-3","price":34.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-ERA600XL-1.webp?v=1779369841","url":"https:\/\/batteryweb.com\/products\/sony-ericsson-xperia-u-replacement-battery-37v-1300mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}