{"product_id":"motorola-mb525-replacement-battery-37v-1300mah-li-ion","title":"Motorola Defy MB525 Replacement Battery BF5X 3.7V 1300mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eMotorola Defy MB525 — 3.7V Li-ion Replacement Battery (BF5X)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 1300mAh Li-ion battery built to the BF5X specification for the Motorola Defy MB525. It fits the MB525, MB520, ME525, and related Defy-series handsets that share the same battery bay and connector. Swap it in when the original cell can no longer hold a working charge through a normal day.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eDefy-series compatibility:\u003c\/strong\u003e\n    The MB525, MB520, and ME525 all use the same 3.7V single-cell bay with an identical three-contact connector and the same BMS handshake protocol — that is why one cell covers the full Defy lineup without modification.\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 Defy MB525 unit, confirmed BMS handshake established correctly on the first cycle, and verified the protection circuit trips cleanly at low-voltage cutoff before the modem rail dropped.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first cycle:\u003c\/strong\u003e\n    After fitting this cell, run one full discharge down to automatic shutdown — do not manually power off — then charge uninterrupted to 100%. The MB525 fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve during this cycle, so percentage readings reflect the actual cell state from that point forward.\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 Defy MB525\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThis is the single most reported symptom after a cell swap on the Defy series. The fuel gauge IC still holds the old cell's discharge curve in memory, so it reports 25% remaining while the actual cell voltage has already dropped to the modem's minimum rail — around 3.2V. When the screen and modem draw simultaneous current, the cell voltage sags below cutoff and the phone shuts off hard. One full discharge-to-shutdown cycle followed by an uninterrupted charge resets the coulomb counter and eliminates the false floor.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eDevice won't power on after sitting in storage with a flat battery\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eIf a Defy MB525 has been stored discharged for weeks or months, the cell can drop below 2.5V — the threshold where the BMS locks out to prevent damage to the lithium chemistry. The phone will show nothing when you press the power button, and a standard charger may not wake it. Connect the phone to a wall adapter — not a PC USB port — and leave it for 15 to 20 minutes without pressing any button. Most BMS circuits on this cell accept a trickle from the charge IC and recover to a level where normal boot is possible; if the voltage returns to around 3.0V, the phone will power on and begin a normal charge cycle.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405101498458,"sku":"BWCS-MOB525SL-1","price":22.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405101531226,"sku":"BWCS-MOB525SL-2","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405101563994,"sku":"BWCS-MOB525SL-3","price":27.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-MOB525SL-1.webp?v=1779369956","url":"https:\/\/batteryweb.com\/products\/motorola-mb525-replacement-battery-37v-1300mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}