{"product_id":"jbl-charge-4-replacement-battery-37v-7800mah-li-ion","title":"JBL Charge 4 Replacement Battery 3.7V 7800mAh Li-ion ID998","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eJBL Charge 4 \/ Charge 4J — 3.7V Li-ion Replacement Battery (ID998)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 7800mAh Li-ion cell replaces the original battery in the JBL Charge 4, Charge 4J, JBLCHARGE4BLUAM, and Charge 4BLK. It restores both wireless audio playback and the speaker's USB power-bank function. Capacity is rated at 28.86Wh — matching the original cell specification.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCharge 4 series compatibility:\u003c\/strong\u003e\n    All four Charge 4 variants — Charge 4, Charge 4J, JBLCHARGE4BLUAM, and Charge 4BLK — share the same battery bay dimensions (66.30 x 38.50 x 36.30mm), the same 3.7V cell voltage, and the same BMS connector pinout. The ID998 cell fits all four without modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this cell through charge and discharge cycles on a Charge 4 unit. The BMS accepted the cell immediately, balanced charge current correctly across stages, and the USB power-bank output activated at full charge without prompting a reset.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eFuel gauge calibration after swap:\u003c\/strong\u003e\n    After fitting this battery, run the speaker down until it powers off automatically — do not interrupt it. Then charge it uninterrupted to 100%. This lets the BMS re-learn the cell's actual capacity and stops the charge indicator from reading full when the cell is only at 60–70%.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eCapacity fade from constant top-off charging on the Charge 4\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eThe Charge 4 is often left plugged in on a desk between uses. Li-ion cells held at 100% charge under trickle current degrade faster than cells that cycle between 20% and 80%. The BMS cannot prevent this — it only stops overcharge, not prolonged float voltage stress. If the original battery lost capacity quickly, the charging habit is usually the cause. With a replacement cell, occasional full discharge cycles slow that fade significantly.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eUSB power-bank output not waking up on a deeply discharged pack\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Charge 4's USB-A output port requires the cell to sit above approximately 3.0V before the boost converter activates. A deeply discharged pack — one left unused for several months — can drop below that threshold and appear completely dead. Plug the speaker into its own charger via USB-C and leave it for at least 20–30 minutes before testing the USB output port. The BMS uses a low-current pre-charge phase to bring the cell back above the minimum acceptance voltage before resuming normal charge rate.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43416222040154,"sku":"BWCS-JML400SL-1","price":43.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43416222072922,"sku":"BWCS-JML400SL-2","price":50.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43416222105690,"sku":"BWCS-JML400SL-3","price":56.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-JML400SL-1.webp?v=1779760990","url":"https:\/\/batteryweb.com\/products\/jbl-charge-4-replacement-battery-37v-7800mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}