{"product_id":"t-mobile-unity-replacement-battery-37v-800mah-li-ion","title":"T-Mobile Unity HB4A3 Replacement Battery 3.7V 800mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eT-Mobile Unity \/ Groove \/ Panama — 3.7V Li-ion Replacement Battery (HB4A3)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 800mAh Li-ion cell that replaces part number HB4A3 in the T-Mobile Unity, Groove, and Panama smartphones. All three models share the same battery footprint and connector, making this a single-part fix across the range. Capacity is rated at 2.96Wh, matching the original cell specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eUnity, Groove, and Panama compatibility:\u003c\/strong\u003e\n    These three T-Mobile handsets use the same 53.00 × 34.00 × 4.80mm cell with an identical connector pinout and BMS handshake protocol — one part number covers all three 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 load on a Unity unit. The BMS accepted charge without fault flags, and voltage held stable under screen-on and modem-active load conditions through multiple cycles.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first cycle:\u003c\/strong\u003e\n    After installation, run one full discharge to automatic shutoff, then charge uninterrupted to 100% before normal use. This resets the coulomb counter against the new cell's discharge curve so percentage readings stay accurate from day one.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Unity reports the wrong battery percentage after a cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe fuel gauge IC on these T-Mobile handsets builds its percentage model from historical charge and discharge data tied to the old cell. When a new cell goes in, that learned curve no longer matches the actual voltage-to-capacity relationship of the replacement. The OS reads a voltage that maps to the wrong percentage on the old curve, so the number on screen drifts. One full discharge-charge cycle forces the gauge IC to rebuild its model against the new cell, correcting the readout.\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 cell voltage drops sharply under high-current draw — modem activity or screen brightness spikes — before the gauge IC has recalibrated. The phone sees a voltage cliff and interprets it as critical low battery, triggering an emergency shutdown even though the gauge still shows charge remaining. It is not a defective cell; it is an uncalibrated coulomb counter. Complete the first full discharge cycle and charge to 100% without interruption — after that, the IC tracks the real cutoff voltage and the shutdowns stop.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405050118234,"sku":"BWCS-HUG620SL-1","price":21.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405050151002,"sku":"BWCS-HUG620SL-2","price":24.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405050183770,"sku":"BWCS-HUG620SL-3","price":26.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-HUG620SL-1.webp?v=1779369883","url":"https:\/\/batteryweb.com\/products\/t-mobile-unity-replacement-battery-37v-800mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}