{"product_id":"pantech-jest-txt8040-replacement-battery-37v-800mah-li-ion","title":"Pantech Jest TXT8040 Replacement Battery BTR-8030 3.7V 800mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003ePantech Jest TXT8040 — 3.7V Li-ion Replacement Battery (BTR-8030)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 800mAh Li-ion battery replaces the original cell in the Pantech Jest TXT8040 and Razzle Jest series. It also covers OEM part numbers BTR-8030B, TXT8030, and BTR8045B. If your original cell no longer holds charge or the phone shuts down unexpectedly, this is the direct swap.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eJest TXT8040 and Razzle Jest compatibility:\u003c\/strong\u003e\n    These models share the same voltage rail, connector pinout, and BMS handshake protocol. The physical footprint — 51.80 x 37.60 x 4.70mm — matches the battery bay exactly, so no modifications are needed during installation.\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 the Jest platform. The BMS accepted the handshake without fault codes, and charge termination triggered correctly at full capacity.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge recalibration on first use:\u003c\/strong\u003e\n    After installation, run one complete discharge to near-empty before recharging fully. The Jest's fuel gauge IC was calibrated to the original cell's discharge curve — a full cycle against the new cell lets it reset that baseline for accurate percentage readings.\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 Jest TXT8040\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis is a voltage-cliff failure. At 20–30% reported charge, the new cell's voltage drops faster than the phone's fuel gauge expects under load from the screen or radio module. The phone interprets this as a fatal undervoltage condition and shuts down rather than browning out the display. The fix is one complete discharge-charge cycle so the coulomb counter maps the actual discharge curve of the new cell. After that cycle, the reported percentage should align with real remaining capacity.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003ePhone showing wrong battery percentage after cell swap\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Jest's fuel gauge IC stores a discharge model built around the original cell's internal resistance and capacity curve. A new cell has different characteristics, so the IC reports inaccurate percentages — often jumping erratically or reading full charge well before the cell is actually topped up. Run the phone from 100% down to automatic shutdown, then charge uninterrupted to 100%. This single full cycle forces the IC to recalibrate against the new cell. Percentage readings stabilise at 4.2V full charge.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43405129973850,"sku":"BWCS-AU8030SL-1","price":22.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43405130006618,"sku":"BWCS-AU8030SL-2","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43405130039386,"sku":"BWCS-AU8030SL-3","price":27.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-AU8030SL-1.webp?v=1779369992","url":"https:\/\/batteryweb.com\/products\/pantech-jest-txt8040-replacement-battery-37v-800mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}