{"product_id":"jitterbug-sph-a120-replacement-battery-37v-750mah-li-ion","title":"Jitterbug SPH-A120 Replacement Battery 3.7V 750mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eJitterbug SPH-A120 — 3.7V Li-ion Replacement Battery (BST5339WA)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 750mAh Li-ion cell replaces the original battery in the Jitterbug SPH-A120 and SPHA120CAB flip phones. It matches OEM part numbers BST5339WA, BST5339DA, and BTIA10G. Voltage and physical dimensions are matched to the original spec to ensure the BMS accepts the new cell without a handshake error.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eSPH-A120 and SPHA120CAB fitment:\u003c\/strong\u003e\n    Both models share the same battery bay geometry, connector pinout, and BMS communication protocol — one cell fits both 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, standby, and call-load draw. The BMS accepted the cell on first connection, held the charge curve within spec, and tripped the protection circuit correctly at the low-voltage threshold.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration after swap:\u003c\/strong\u003e\n    On first use after installation, run one full discharge down to automatic cutoff, then charge uninterrupted to 100%. This gives the fuel gauge IC a clean reference point against the new cell's discharge curve before the phone starts reporting percentage.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the SPH-A120 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe SPH-A120 uses a fuel gauge IC that builds its percentage model from the coulomb counter data of the previous cell. When you swap the battery, that stored curve no longer matches the new cell's actual capacity. The phone reads voltage and maps it to the old model, so it can show 60% when the cell is nearly flat. One full discharge-to-cutoff followed by a complete uninterrupted charge resets the reference and brings the percentage readings back in line.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% on the replacement cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens when the fuel gauge IC hasn't recalibrated and the cell hits a voltage cliff faster than the meter predicts. Under the load of an outgoing call, the cell voltage drops sharply — the protection circuit reads it as a low-voltage fault and cuts power before the displayed percentage reaches zero. It's not a faulty cell; it's an uncalibrated gauge. Run one complete discharge-charge cycle without interruption and the shutdowns stop. If they continue past two full cycles, check that the terminal voltage at full charge reaches 4.2V.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409448173658,"sku":"BWCS-SPH120SL-1","price":23.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 2 Year","offer_id":43409448206426,"sku":"BWCS-SPH120SL-2","price":26.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 3 Year","offer_id":43409448239194,"sku":"BWCS-SPH120SL-3","price":28.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-SPH120SL-big.webp?v=1779579708","url":"https:\/\/batteryweb.com\/products\/jitterbug-sph-a120-replacement-battery-37v-750mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}