{"product_id":"samsung-sgh-z300-replacement-battery-37v-750mah-li-ion","title":"Samsung SGH-Z300 Compatible Battery 3.7V 750mAh ST4309VE","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSamsung SGH-Z300 Series — 3.7V Li-ion Replacement Battery (ST4309VE)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 3.7V, 750mAh Li-ion cell replacing the original ST4309VE battery in Samsung's SGH-Z300 clamshell phone. It also fits the SGH-Z308, ZM60, and ZM-60 variants that share the same connector and BMS handshake. Dimensions are 66.21 × 42.34 × 6.97mm — confirm your original against those before ordering.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eSGH-Z300, Z308, ZM60 fitment:\u003c\/strong\u003e\n    These four models share the same battery bay dimensions, positive terminal orientation, and BMS communication protocol. The ST4309VE part number covers the entire group — no separate SKU exists for each variant.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through full charge and discharge on Z-series hardware. The BMS accepted charge handshake on the first connect, held the 4.2V charge ceiling cleanly, and triggered low-voltage cutoff at the expected threshold without false trips.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFirst-cycle fuel gauge reset:\u003c\/strong\u003e\n    After fitting this cell, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before use. The SGH-Z300's fuel gauge IC was calibrated to the old cell's discharge curve — skipping this step causes the percentage counter to read inaccurately for weeks.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the SGH-Z300 reports wrong battery percentage after a cell swap\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe SGH-Z300 uses a coulomb counter IC that builds its fuel gauge model from accumulated charge and discharge data on the installed cell. When you swap in a new cell, that learned curve no longer matches the new cell's actual capacity and impedance. The phone uses the old data until it completes at least one full discharge-charge cycle with the new cell. Until recalibration happens, the percentage display can read 40% and drop to zero without warning.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eSudden shutdown at 20–30% battery remaining\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis is a voltage cliff failure, not a capacity problem. The Z300's display and radio draw simultaneous current spikes — particularly during a call with the backlight active — that the cell cannot sustain if its internal impedance is high. Voltage drops below the modem's minimum operating threshold in milliseconds and the phone cuts off. If this happens on a new cell, run the full recalibration cycle first. If it persists after one full cycle, check that the terminal contacts are fully seated — a partial connection raises effective impedance and triggers the same collapse at around 3.5V.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43409452695642,"sku":"BWCS-SMZ300SL-1","price":23.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 2 Year","offer_id":43409452728410,"sku":"BWCS-SMZ300SL-2","price":26.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 3 Year","offer_id":43409452761178,"sku":"BWCS-SMZ300SL-3","price":28.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-SMZ300SL-big.webp?v=1779579736","url":"https:\/\/batteryweb.com\/products\/samsung-sgh-z300-replacement-battery-37v-750mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}